Transmission Activity
01-10-2007 | 11:43 PM
#91
Guest
Posts: n/a
Re: Transmission Activity
Gordon McGrew wrote:
> On Mon, 08 Jan 2007 21:25:13 -0800, jim beam
> <spamvortex@bad.example.net> wrote:
>
>> Gordon McGrew wrote:
>>> On Sun, 07 Jan 2007 15:20:11 -0800, jim beam
>>> <spamvortex@bad.example.net> wrote:
>>>
>>>>>>>>> The problem with most (virtually all) ATs is that they are biased
>>>>>>>>> toward automatic operation and discourage manual operation.
>>>>>>>> how? my auto has the shift in exactly the same place as where the stick
>>>>>>>> would be. i see no difference. the transmission even has a no-lock
>>>>>>>> gate between 3rd & 4th [commonest manual override] especially so you
>>>>>>>> /can/ flip up and down at will.
>>>>>>> If you put it in 4, will it ever downshift into 3 by itself?
>>>>>> yes, absolutely. it does it on "kickdown" acceleration /and/ it does it
>>>>>> on braking. not gentle braking, but harder braking.
>>>>> It is not a bad thing, I just don't care for it. If I want to
>>>>> downshift, I can do that. If I don't want to, I don't like the car
>>>>> doing it on its own.
>>>> why not? it's just like you'd have on a stick.
>>> Not sure I understand. My GS-R never downshifts on its own.
>> if it doesn't, then there's something wrong. how old is it?
>
> It is a '94 with a 5-speed manual transmission. What kind of MT cars
> have you driven that shift themselves???
i misunderstood you.
originally, you said "If I want to downshift, I can do that." well, you
can on an auto. on my car, the shifter is in the same place as a stick
would be too. and the auto replicates engine braking when you need it -
just like you'd do yourself. really, it's a good system.
>
>
>>>>>>> When you
>>>>>>> shift into 3 does it effectively double clutch?
>>>>>> pointless exercise on an automatic. but even then, on the modern autos,
>>>>>> in conjunction with electronic throttle, yes, the engine revs /are/
>>>>>> meshed to the gear on shift.
>>>>> That is what I mean. I figured they had fixed that aspect which is
>>>>> the worst part of the older ATs.
>>>>>
>>>>>>>>> Also, I
>>>>>>>>> don't particularly care for the slippage of the torque converter.
>>>>>>>> eh? what "slippage" is that? how does its mechanical function differ
>>>>>>> >from a clutch [other than it has a much better efficiency range and is
>>>>>>>> much smoother of course]?
>>>>>>> Well, as you point out, I don't have any experience with modern high
>>>>>>> end luxury cars, but I note that at least more modest cars generally
>>>>>>> have a significantly greater 0-60 speed and a lower mpg rating. Since
>>>>>>> they now mostly have five gears, I would assume that means they are
>>>>>>> slipping.
>>>>>> there's no slipping unless the lock-up clutch is released. see below.
>>>>>>
>>>>>>> Actually, the slipping is partly by design, the so-called
>>>>>>> torque multiplier effect.
>>>>>> yes, that's what a torque converter does.
>>>>>>
>>>>>>> Basically, if you are cruising along and
>>>>>>> you give it a little gas, but not enough to force a downshift, you
>>>>>>> will see the rpms jump up immediately.
>>>>>> that's because the lockup clutch is released to allow more torque. more
>>>>>> flexibility than a stick where you'd have to shift.
>>>>> But that is the slippage. The engine speeds up races up ahead of any
>>>>> change in vehicle speed.
>>>> but i don't understand the problem - what's wrong with it? engines are
>>>> not perfect across all rev ranges - why not let a computer manage the
>>>> efficiency curves - for that's what's happening.
>>> It is just a personal preference. I like the engine to be positively
>>> coupled to the wheels.
>> that's what the lockup clutch in the torque converter is for.
>
> But it isn't engaged all the time. When it disengages, that is when
> it "slips" and I do not find that satisfying as a driver.
you'd hate cvt. as i said before, there's zero relation between engine
speed and vehicle speed - if you drive on engine revs, and it sounds
like you do, you'll be suffering total loss of feedback.
> Like I said
> a the outside, it is a preference for MT. I like to drive cars and
> the MT is more enjoyable than the ATs I have driven. I don't like it
> shifting when I don't want it to and I don't like the slippy feel of
> the torque converter. The fact that the MT is usually faster and more
> fuel efficient is a bonus.
check the modern civics in that department.
>
>
>>>>> It is like a slipping clutch. As for more
>>>>> torque (horsepower really) a lot of that is eaten up by the
>>>>> inefficiency of the torque converter.
>>>> how is a slipping clutch more efficient? [it's not.]
>>> No, I understand that (unlike a slipping clutch) there is a benefit to
>>> the slip designed into the AT. I just don't like the feel of it and
>>> the benefit is more than eaten up by the inefficiencies that come with
>>> it.
>> you'd hate cvt. there's no "relationship" between revs and engine speed
>> at all.
>
> I think you are probably right. That is why I mentioned the fact that
> the CVT isn't very popular in the US (if anywhere) and I think it is
> because lots of people hate it. Why else would Honda sell a 7-speed
> CVT?
because they rely on dealer feedback, and dealers are morons? cvt was
pretty popular in europe iirc. volvo sold them as well as daf, and they
did quite well.
>
> OTOH, it probably appeals to - or at least doesn't repulse - the
> hybrid buyer because it befits the unconventional nature of the car. I
> realize there are technical benefits to the combination of hybrid and
> CVT, but I am saying that the unconventional nature of the CVT is less
> of a negative when you are already committed to buying an
> unconventional vehicle. If you are attracted to the hybrid because it
> is unconventional, the CVT is a plus.
nah, it's a pure engineering logic decision. cvt allows extremely good
engine efficiency. if you don't want that, you don't want a hybrid.
>
>>>>> On cars where you can get a MT
>>>>> or AT with the same engine, the MT is almost always faster and gets
>>>>> better mileage.
>>>> not so with the modern autos. and that's one of the big things about
>>>> honda autos - it's basically a standard transmission with clutch packs
>>>> instead of synchros. inherently more efficient than planetary gears.
>>> Looking at the differences between the ATs in the econo cars tested by
>>> CR, Honda looks about as good as the other ATs (except for the CVT.)
>> you're looking at fuel economy, right?
>
> Fuel economy was significantly better for the MTs but the biggest
> difference was acceleration. The MTs blew the doors off the ATs. In
> terms of 0 - 60 time differences, the Yaris AT was the best - "only"
> 2.1 seconds slower than the MT version. Even the slowest MT car, the
> Kia Rio was faster than the Versa CVT. The fastest AT car, the Yaris,
> was 1.4 seconds slower than the Versa CVT.
dude, compare like with like - not different car to different car if
you're trying to compare trnasmissions, i.e. yaris with cvt, yaris with
stick, etc. yaris stick to versa cvt doesn't work.
>
>>>>>>> The ultimate "torque multiplier" is a CVT.
>>>>>> that's different - it's not a torque multiplier.
>>>>> Neither is the conventional AT, it just has a clever design to let the
>>>>> engine speed up ahead of the vehicle speed without shifting. It is
>>>>> basically like a limited range CVT.
>>>> no dude, they're totally different. "torque multiplier" is something a
>>>> torque converter can do - hence its name. everything else is ratio
>>>> control, be it continuously variable or discrete.
>>> OK, explain it to me. My understanding is that it is just a trick to
>>> get the engine running at a slightly higher rpm to produce more power.
>>> Kind of like a mini downshift. All car transmissions are torque
>>> multipliers.
>> ok, yes, but we're talking about different things. torque converters
>> can increase torque output from a little to a lot in a very limited rev
>> range. ratio change is something different and that's what the gears
>> are for.
>
> You understand that the ATs torque output at a certain rpm (i.e. power
> transmitted) is higher when the torque multiplication is active. There
> are only two way this can happen. The first is to increase the
> efficiency of the transmission. I think we can dismiss that. The
> other way is to increase the power input.
no, it depends on input/output speed differential. within certain rev
ranges, torque transmission is very high, even with a rev differential.
if it gets outside of that band, it drops right off.
> The only way to do that is
> to increase the throttle opening or increase the rpm. The throttle
> opening is determined by your foot (and it wouldn't be much of a trick
> for the torque multiplier to be just an extra jerk on the throttle and
> it wouldn't do much good if the throttle were already wide open.)
> However, rpm is largely controlled by the transmission. The
> transmission allows the engine to run a little faster and therefore
> produce more power which is transmitted to the wheels. This is what I
> meant by a mini downshift.
that's the lockup clutch releasing.
>
>>> They take high rpm/low torque and turn it into low rpm
>>> high torque. If it were perfectly efficient, the power output would
>>> be equal to input but of course it is always less. No way to get more
>>> power out unless you put more power in, i.e. run the engine at higher
>>> rpm.
>> see above.
>>
>>>>>> if is however a great
>>>>>> way of achieving absolute optimum gear for all conditions.
>>>>> I agree that it has a big theoretical advantage, especially compared
>>>>> to a conventional AT.
>>>> compared to /any/ transmission. there are mechanical efficiency issues
>>>> with the friction interface, but that is more than outweighed by ratio
>>>> flexibility and ability to keep the engine at its most efficient.
>>> The why doesn't the Versa with a CVT get better mileage or accelerate
>>> faster than the Versa with an MT? Unfortunately, there are few cars
>>> which allow you to directly compare CVT vs. MT.
>> civic hx was significantly more fuel efficient than the stick.
>
> I gather that was the CVT-equipped model. They don't sell it anymore.
> I guess people hated it more than high fuel costs.
my money's on dealer prejudice, not consumer. by the same token, the
hatchback has been all but dropped in the u.s. afaikt, that's more to
do with vehicles with the same utility selling for $30k rather than $15k
for a hatch, not consumer demand. try buying a used hatchback civic
here in the bay area - good luck! people just keep them - they never
sell.
>
>>>>>>> A lot of people don't like
>>>>>>> them at all, but others say they get used to it. (The perception
>>>>>>> problem is so bad that some manufacturers program virtual gears into
>>>>>>> them thereby defeating the chief advantage of the CVT.)
>>>>>> absolutely! i drove a "real" cvt one when i was in europe years ago,
>>>>>> and yes it is /real/ weird at first. but it's amazing how much you can
>>>>>> get out of a small 2-cylinder engine when it's got perfect gearing.
>>>>>> quite fun! this particular model had 2 independent drives too, so not
>>>>>> only did you have optimum gearing, you had limited slip diff benefits in
>>>>>> snow & ice too.
>>>>>> http://www.ritzsite.demon.nl/DAF/DAF_cars_p2.htm
>>>>> That was the original CVT. Do you remember who offered the first CVT
>>>>> in the US. (I don't think they ever sold the Daffodil here.)
>>>> subaru?
>>> That is what I recall. The car was called the Justy.
>>>
>>>>>>> I only rode
>>>>>>> in one CVT car, a Nissan luxury sedan in Japan and it wasn't bad in
>>>>>>> that application. He drove it fairly aggressively too - we hit almost
>>>>>>> 180 kph on the expressway. I would like to try one of these. I don't
>>>>>>> know if I would like it or not.
>>>>>> if you're not used to traditional automatics, the transition is easy.
>>>>>> if you're used to traditional autos, its weird for a few minutes because
>>>>>> it doesn't "shift", but beyond that, they're actually very impressive.
>>>>> Again though, I am not sure they are any faster or more efficient than
>>>>> a good MT.
>>>> well, the daf was only 650cc iirc, and 0-30, that wasn't much to touch it.
>>> I think the Honda 600 would have blown its petals off. ;-)
>>>
>>>>> Consumer Reports tested the Versa with MT and with CVT.
>>>>> The MT version was 0.6 seconds faster to 60 and got one more mpg. (And
>>>>> CR panned that MT.) They also tested MT and (conventional) AT
>>>>> versions of Fit, Rio, Accent and Yaris. In each case the MT was 2 - 3
>>>>> seconds faster and got 2 more mpg, so the CVT was clearly better than
>>>>> an AT but not as good as even a mediocre MT, at last on raw numbers.
>>>> that depends on the management system. the modern cvt's "simulate" gear
>>>> shifts which is the dumbest damned thing since it's not utilizing the
>>>> inherent benefit of the system! on that basis, i'm not surprised.
>>> Does the Versa do that? CR didn't mention it.
>> don't know. given "consumer demand", i expect so.
>
> Like I said, they hate it just like you think I would. (Actually I
> would love to try one, I do think it is a neat idea and it would be
> fun for a while at least. Only after the novelty wore off could I
> tell you if I like it or hate it. I actually suspect that I would
> like it more than a conventional AT.)
>
> Here is an interesting review I found. (It indicates that the Versa
> CVT does not have "gears," so the fact that it was slower and less
> fuel efficient than the "clunky" MT is significant.) I made one
> editorial comment in brackets.
>
> --quote--
> But the CVT is the one that shines. Its proprietary design, benefiting
> from Nissan's global cooperation with French carmaker Renault, is
> uncanny in the way it maintains optimal engine rpm within the most
> fuel-efficient torque range. It senses, for example, when the Versa is
> proceeding downhill and glides effortlessly into a lower gear range to
> slow the car with engine braking. [What if you don't want engine
> braking? It is wasting kinetic energy = fuel.
not correct. when engine braking, fuel delivery is completely stopped.
> What it needs in a
> powerful computer with optical sensors to look ahead, evaluate the
> situation and decide whether engine braking is advantageous
why? i don't want my car making /that/ kind of decision. seriously,
auto engine braking only happens when you're foot braking - just like on
a stick. you can't criticize what you've not used dude.
>.]
> Conversely, under pedal-to-the-floor acceleration, the CVT instantly
> launches the engine to its max-torque rpm, then keeps it there
> unchanged until a desired highway speed is reached.
>
> This goes against every traditional sensation of driving, wherein gear
> changes trigger a momentary drop in rpm as the higher gear ratio is
> engaged. There's a lot of mechanical inefficiency in that traditional
> gear-change syncopation; and Versa's CVT eliminates it. When first
> experiencing the CVT's behavior, it feels wrong, sounds noisy. In
> truth, however, it's mostly the lack of noticeable gear changes that's
> merely thwarting a driver's subconscious expectation of rising-falling
> rpms as gears change.
> --end quote--
>
> http://www.carlist.com/newcars/2007/ncr1116.html
>
>
>>>>> And yet, there is hardly a proliferation of CVTs on the market. Most
>>>>> of them seem to be on hybrids in fact.
>>>> that's consumer and mechanic inertia - nothing to do with benefits or
>>>> reliability. trust me on that one - i've driven the daf for an extended
>>>> period and it's a great system.
>>> Maybe. I would gladly trade the AT in my Ody for one if it was proven
>>> reliable. Not all are. The on in the Saturn Vue was a disaster, but
>>> I guess you have to expect that from GM. The Japanese units don't
>>> seem to have any problems.
>> i've never heard of problems with the civic hx.
>
> Neither have I, but then there aren't a lot out there.
/all/ the 96-2000 hx autos are cvt.
> On Mon, 08 Jan 2007 21:25:13 -0800, jim beam
> <spamvortex@bad.example.net> wrote:
>
>> Gordon McGrew wrote:
>>> On Sun, 07 Jan 2007 15:20:11 -0800, jim beam
>>> <spamvortex@bad.example.net> wrote:
>>>
>>>>>>>>> The problem with most (virtually all) ATs is that they are biased
>>>>>>>>> toward automatic operation and discourage manual operation.
>>>>>>>> how? my auto has the shift in exactly the same place as where the stick
>>>>>>>> would be. i see no difference. the transmission even has a no-lock
>>>>>>>> gate between 3rd & 4th [commonest manual override] especially so you
>>>>>>>> /can/ flip up and down at will.
>>>>>>> If you put it in 4, will it ever downshift into 3 by itself?
>>>>>> yes, absolutely. it does it on "kickdown" acceleration /and/ it does it
>>>>>> on braking. not gentle braking, but harder braking.
>>>>> It is not a bad thing, I just don't care for it. If I want to
>>>>> downshift, I can do that. If I don't want to, I don't like the car
>>>>> doing it on its own.
>>>> why not? it's just like you'd have on a stick.
>>> Not sure I understand. My GS-R never downshifts on its own.
>> if it doesn't, then there's something wrong. how old is it?
>
> It is a '94 with a 5-speed manual transmission. What kind of MT cars
> have you driven that shift themselves???
i misunderstood you.
originally, you said "If I want to downshift, I can do that." well, you
can on an auto. on my car, the shifter is in the same place as a stick
would be too. and the auto replicates engine braking when you need it -
just like you'd do yourself. really, it's a good system.
>
>
>>>>>>> When you
>>>>>>> shift into 3 does it effectively double clutch?
>>>>>> pointless exercise on an automatic. but even then, on the modern autos,
>>>>>> in conjunction with electronic throttle, yes, the engine revs /are/
>>>>>> meshed to the gear on shift.
>>>>> That is what I mean. I figured they had fixed that aspect which is
>>>>> the worst part of the older ATs.
>>>>>
>>>>>>>>> Also, I
>>>>>>>>> don't particularly care for the slippage of the torque converter.
>>>>>>>> eh? what "slippage" is that? how does its mechanical function differ
>>>>>>> >from a clutch [other than it has a much better efficiency range and is
>>>>>>>> much smoother of course]?
>>>>>>> Well, as you point out, I don't have any experience with modern high
>>>>>>> end luxury cars, but I note that at least more modest cars generally
>>>>>>> have a significantly greater 0-60 speed and a lower mpg rating. Since
>>>>>>> they now mostly have five gears, I would assume that means they are
>>>>>>> slipping.
>>>>>> there's no slipping unless the lock-up clutch is released. see below.
>>>>>>
>>>>>>> Actually, the slipping is partly by design, the so-called
>>>>>>> torque multiplier effect.
>>>>>> yes, that's what a torque converter does.
>>>>>>
>>>>>>> Basically, if you are cruising along and
>>>>>>> you give it a little gas, but not enough to force a downshift, you
>>>>>>> will see the rpms jump up immediately.
>>>>>> that's because the lockup clutch is released to allow more torque. more
>>>>>> flexibility than a stick where you'd have to shift.
>>>>> But that is the slippage. The engine speeds up races up ahead of any
>>>>> change in vehicle speed.
>>>> but i don't understand the problem - what's wrong with it? engines are
>>>> not perfect across all rev ranges - why not let a computer manage the
>>>> efficiency curves - for that's what's happening.
>>> It is just a personal preference. I like the engine to be positively
>>> coupled to the wheels.
>> that's what the lockup clutch in the torque converter is for.
>
> But it isn't engaged all the time. When it disengages, that is when
> it "slips" and I do not find that satisfying as a driver.
you'd hate cvt. as i said before, there's zero relation between engine
speed and vehicle speed - if you drive on engine revs, and it sounds
like you do, you'll be suffering total loss of feedback.
> Like I said
> a the outside, it is a preference for MT. I like to drive cars and
> the MT is more enjoyable than the ATs I have driven. I don't like it
> shifting when I don't want it to and I don't like the slippy feel of
> the torque converter. The fact that the MT is usually faster and more
> fuel efficient is a bonus.
check the modern civics in that department.
>
>
>>>>> It is like a slipping clutch. As for more
>>>>> torque (horsepower really) a lot of that is eaten up by the
>>>>> inefficiency of the torque converter.
>>>> how is a slipping clutch more efficient? [it's not.]
>>> No, I understand that (unlike a slipping clutch) there is a benefit to
>>> the slip designed into the AT. I just don't like the feel of it and
>>> the benefit is more than eaten up by the inefficiencies that come with
>>> it.
>> you'd hate cvt. there's no "relationship" between revs and engine speed
>> at all.
>
> I think you are probably right. That is why I mentioned the fact that
> the CVT isn't very popular in the US (if anywhere) and I think it is
> because lots of people hate it. Why else would Honda sell a 7-speed
> CVT?
because they rely on dealer feedback, and dealers are morons? cvt was
pretty popular in europe iirc. volvo sold them as well as daf, and they
did quite well.
>
> OTOH, it probably appeals to - or at least doesn't repulse - the
> hybrid buyer because it befits the unconventional nature of the car. I
> realize there are technical benefits to the combination of hybrid and
> CVT, but I am saying that the unconventional nature of the CVT is less
> of a negative when you are already committed to buying an
> unconventional vehicle. If you are attracted to the hybrid because it
> is unconventional, the CVT is a plus.
nah, it's a pure engineering logic decision. cvt allows extremely good
engine efficiency. if you don't want that, you don't want a hybrid.
>
>>>>> On cars where you can get a MT
>>>>> or AT with the same engine, the MT is almost always faster and gets
>>>>> better mileage.
>>>> not so with the modern autos. and that's one of the big things about
>>>> honda autos - it's basically a standard transmission with clutch packs
>>>> instead of synchros. inherently more efficient than planetary gears.
>>> Looking at the differences between the ATs in the econo cars tested by
>>> CR, Honda looks about as good as the other ATs (except for the CVT.)
>> you're looking at fuel economy, right?
>
> Fuel economy was significantly better for the MTs but the biggest
> difference was acceleration. The MTs blew the doors off the ATs. In
> terms of 0 - 60 time differences, the Yaris AT was the best - "only"
> 2.1 seconds slower than the MT version. Even the slowest MT car, the
> Kia Rio was faster than the Versa CVT. The fastest AT car, the Yaris,
> was 1.4 seconds slower than the Versa CVT.
dude, compare like with like - not different car to different car if
you're trying to compare trnasmissions, i.e. yaris with cvt, yaris with
stick, etc. yaris stick to versa cvt doesn't work.
>
>>>>>>> The ultimate "torque multiplier" is a CVT.
>>>>>> that's different - it's not a torque multiplier.
>>>>> Neither is the conventional AT, it just has a clever design to let the
>>>>> engine speed up ahead of the vehicle speed without shifting. It is
>>>>> basically like a limited range CVT.
>>>> no dude, they're totally different. "torque multiplier" is something a
>>>> torque converter can do - hence its name. everything else is ratio
>>>> control, be it continuously variable or discrete.
>>> OK, explain it to me. My understanding is that it is just a trick to
>>> get the engine running at a slightly higher rpm to produce more power.
>>> Kind of like a mini downshift. All car transmissions are torque
>>> multipliers.
>> ok, yes, but we're talking about different things. torque converters
>> can increase torque output from a little to a lot in a very limited rev
>> range. ratio change is something different and that's what the gears
>> are for.
>
> You understand that the ATs torque output at a certain rpm (i.e. power
> transmitted) is higher when the torque multiplication is active. There
> are only two way this can happen. The first is to increase the
> efficiency of the transmission. I think we can dismiss that. The
> other way is to increase the power input.
no, it depends on input/output speed differential. within certain rev
ranges, torque transmission is very high, even with a rev differential.
if it gets outside of that band, it drops right off.
> The only way to do that is
> to increase the throttle opening or increase the rpm. The throttle
> opening is determined by your foot (and it wouldn't be much of a trick
> for the torque multiplier to be just an extra jerk on the throttle and
> it wouldn't do much good if the throttle were already wide open.)
> However, rpm is largely controlled by the transmission. The
> transmission allows the engine to run a little faster and therefore
> produce more power which is transmitted to the wheels. This is what I
> meant by a mini downshift.
that's the lockup clutch releasing.
>
>>> They take high rpm/low torque and turn it into low rpm
>>> high torque. If it were perfectly efficient, the power output would
>>> be equal to input but of course it is always less. No way to get more
>>> power out unless you put more power in, i.e. run the engine at higher
>>> rpm.
>> see above.
>>
>>>>>> if is however a great
>>>>>> way of achieving absolute optimum gear for all conditions.
>>>>> I agree that it has a big theoretical advantage, especially compared
>>>>> to a conventional AT.
>>>> compared to /any/ transmission. there are mechanical efficiency issues
>>>> with the friction interface, but that is more than outweighed by ratio
>>>> flexibility and ability to keep the engine at its most efficient.
>>> The why doesn't the Versa with a CVT get better mileage or accelerate
>>> faster than the Versa with an MT? Unfortunately, there are few cars
>>> which allow you to directly compare CVT vs. MT.
>> civic hx was significantly more fuel efficient than the stick.
>
> I gather that was the CVT-equipped model. They don't sell it anymore.
> I guess people hated it more than high fuel costs.
my money's on dealer prejudice, not consumer. by the same token, the
hatchback has been all but dropped in the u.s. afaikt, that's more to
do with vehicles with the same utility selling for $30k rather than $15k
for a hatch, not consumer demand. try buying a used hatchback civic
here in the bay area - good luck! people just keep them - they never
sell.
>
>>>>>>> A lot of people don't like
>>>>>>> them at all, but others say they get used to it. (The perception
>>>>>>> problem is so bad that some manufacturers program virtual gears into
>>>>>>> them thereby defeating the chief advantage of the CVT.)
>>>>>> absolutely! i drove a "real" cvt one when i was in europe years ago,
>>>>>> and yes it is /real/ weird at first. but it's amazing how much you can
>>>>>> get out of a small 2-cylinder engine when it's got perfect gearing.
>>>>>> quite fun! this particular model had 2 independent drives too, so not
>>>>>> only did you have optimum gearing, you had limited slip diff benefits in
>>>>>> snow & ice too.
>>>>>> http://www.ritzsite.demon.nl/DAF/DAF_cars_p2.htm
>>>>> That was the original CVT. Do you remember who offered the first CVT
>>>>> in the US. (I don't think they ever sold the Daffodil here.)
>>>> subaru?
>>> That is what I recall. The car was called the Justy.
>>>
>>>>>>> I only rode
>>>>>>> in one CVT car, a Nissan luxury sedan in Japan and it wasn't bad in
>>>>>>> that application. He drove it fairly aggressively too - we hit almost
>>>>>>> 180 kph on the expressway. I would like to try one of these. I don't
>>>>>>> know if I would like it or not.
>>>>>> if you're not used to traditional automatics, the transition is easy.
>>>>>> if you're used to traditional autos, its weird for a few minutes because
>>>>>> it doesn't "shift", but beyond that, they're actually very impressive.
>>>>> Again though, I am not sure they are any faster or more efficient than
>>>>> a good MT.
>>>> well, the daf was only 650cc iirc, and 0-30, that wasn't much to touch it.
>>> I think the Honda 600 would have blown its petals off. ;-)
>>>
>>>>> Consumer Reports tested the Versa with MT and with CVT.
>>>>> The MT version was 0.6 seconds faster to 60 and got one more mpg. (And
>>>>> CR panned that MT.) They also tested MT and (conventional) AT
>>>>> versions of Fit, Rio, Accent and Yaris. In each case the MT was 2 - 3
>>>>> seconds faster and got 2 more mpg, so the CVT was clearly better than
>>>>> an AT but not as good as even a mediocre MT, at last on raw numbers.
>>>> that depends on the management system. the modern cvt's "simulate" gear
>>>> shifts which is the dumbest damned thing since it's not utilizing the
>>>> inherent benefit of the system! on that basis, i'm not surprised.
>>> Does the Versa do that? CR didn't mention it.
>> don't know. given "consumer demand", i expect so.
>
> Like I said, they hate it just like you think I would. (Actually I
> would love to try one, I do think it is a neat idea and it would be
> fun for a while at least. Only after the novelty wore off could I
> tell you if I like it or hate it. I actually suspect that I would
> like it more than a conventional AT.)
>
> Here is an interesting review I found. (It indicates that the Versa
> CVT does not have "gears," so the fact that it was slower and less
> fuel efficient than the "clunky" MT is significant.) I made one
> editorial comment in brackets.
>
> --quote--
> But the CVT is the one that shines. Its proprietary design, benefiting
> from Nissan's global cooperation with French carmaker Renault, is
> uncanny in the way it maintains optimal engine rpm within the most
> fuel-efficient torque range. It senses, for example, when the Versa is
> proceeding downhill and glides effortlessly into a lower gear range to
> slow the car with engine braking. [What if you don't want engine
> braking? It is wasting kinetic energy = fuel.
not correct. when engine braking, fuel delivery is completely stopped.
> What it needs in a
> powerful computer with optical sensors to look ahead, evaluate the
> situation and decide whether engine braking is advantageous
why? i don't want my car making /that/ kind of decision. seriously,
auto engine braking only happens when you're foot braking - just like on
a stick. you can't criticize what you've not used dude.
>.]
> Conversely, under pedal-to-the-floor acceleration, the CVT instantly
> launches the engine to its max-torque rpm, then keeps it there
> unchanged until a desired highway speed is reached.
>
> This goes against every traditional sensation of driving, wherein gear
> changes trigger a momentary drop in rpm as the higher gear ratio is
> engaged. There's a lot of mechanical inefficiency in that traditional
> gear-change syncopation; and Versa's CVT eliminates it. When first
> experiencing the CVT's behavior, it feels wrong, sounds noisy. In
> truth, however, it's mostly the lack of noticeable gear changes that's
> merely thwarting a driver's subconscious expectation of rising-falling
> rpms as gears change.
> --end quote--
>
> http://www.carlist.com/newcars/2007/ncr1116.html
>
>
>>>>> And yet, there is hardly a proliferation of CVTs on the market. Most
>>>>> of them seem to be on hybrids in fact.
>>>> that's consumer and mechanic inertia - nothing to do with benefits or
>>>> reliability. trust me on that one - i've driven the daf for an extended
>>>> period and it's a great system.
>>> Maybe. I would gladly trade the AT in my Ody for one if it was proven
>>> reliable. Not all are. The on in the Saturn Vue was a disaster, but
>>> I guess you have to expect that from GM. The Japanese units don't
>>> seem to have any problems.
>> i've never heard of problems with the civic hx.
>
> Neither have I, but then there aren't a lot out there.
/all/ the 96-2000 hx autos are cvt.
01-10-2007 | 11:43 PM
#92
Guest
Posts: n/a
Re: Transmission Activity
Gordon McGrew wrote:
> On Mon, 08 Jan 2007 21:25:13 -0800, jim beam
> <spamvortex@bad.example.net> wrote:
>
>> Gordon McGrew wrote:
>>> On Sun, 07 Jan 2007 15:20:11 -0800, jim beam
>>> <spamvortex@bad.example.net> wrote:
>>>
>>>>>>>>> The problem with most (virtually all) ATs is that they are biased
>>>>>>>>> toward automatic operation and discourage manual operation.
>>>>>>>> how? my auto has the shift in exactly the same place as where the stick
>>>>>>>> would be. i see no difference. the transmission even has a no-lock
>>>>>>>> gate between 3rd & 4th [commonest manual override] especially so you
>>>>>>>> /can/ flip up and down at will.
>>>>>>> If you put it in 4, will it ever downshift into 3 by itself?
>>>>>> yes, absolutely. it does it on "kickdown" acceleration /and/ it does it
>>>>>> on braking. not gentle braking, but harder braking.
>>>>> It is not a bad thing, I just don't care for it. If I want to
>>>>> downshift, I can do that. If I don't want to, I don't like the car
>>>>> doing it on its own.
>>>> why not? it's just like you'd have on a stick.
>>> Not sure I understand. My GS-R never downshifts on its own.
>> if it doesn't, then there's something wrong. how old is it?
>
> It is a '94 with a 5-speed manual transmission. What kind of MT cars
> have you driven that shift themselves???
i misunderstood you.
originally, you said "If I want to downshift, I can do that." well, you
can on an auto. on my car, the shifter is in the same place as a stick
would be too. and the auto replicates engine braking when you need it -
just like you'd do yourself. really, it's a good system.
>
>
>>>>>>> When you
>>>>>>> shift into 3 does it effectively double clutch?
>>>>>> pointless exercise on an automatic. but even then, on the modern autos,
>>>>>> in conjunction with electronic throttle, yes, the engine revs /are/
>>>>>> meshed to the gear on shift.
>>>>> That is what I mean. I figured they had fixed that aspect which is
>>>>> the worst part of the older ATs.
>>>>>
>>>>>>>>> Also, I
>>>>>>>>> don't particularly care for the slippage of the torque converter.
>>>>>>>> eh? what "slippage" is that? how does its mechanical function differ
>>>>>>> >from a clutch [other than it has a much better efficiency range and is
>>>>>>>> much smoother of course]?
>>>>>>> Well, as you point out, I don't have any experience with modern high
>>>>>>> end luxury cars, but I note that at least more modest cars generally
>>>>>>> have a significantly greater 0-60 speed and a lower mpg rating. Since
>>>>>>> they now mostly have five gears, I would assume that means they are
>>>>>>> slipping.
>>>>>> there's no slipping unless the lock-up clutch is released. see below.
>>>>>>
>>>>>>> Actually, the slipping is partly by design, the so-called
>>>>>>> torque multiplier effect.
>>>>>> yes, that's what a torque converter does.
>>>>>>
>>>>>>> Basically, if you are cruising along and
>>>>>>> you give it a little gas, but not enough to force a downshift, you
>>>>>>> will see the rpms jump up immediately.
>>>>>> that's because the lockup clutch is released to allow more torque. more
>>>>>> flexibility than a stick where you'd have to shift.
>>>>> But that is the slippage. The engine speeds up races up ahead of any
>>>>> change in vehicle speed.
>>>> but i don't understand the problem - what's wrong with it? engines are
>>>> not perfect across all rev ranges - why not let a computer manage the
>>>> efficiency curves - for that's what's happening.
>>> It is just a personal preference. I like the engine to be positively
>>> coupled to the wheels.
>> that's what the lockup clutch in the torque converter is for.
>
> But it isn't engaged all the time. When it disengages, that is when
> it "slips" and I do not find that satisfying as a driver.
you'd hate cvt. as i said before, there's zero relation between engine
speed and vehicle speed - if you drive on engine revs, and it sounds
like you do, you'll be suffering total loss of feedback.
> Like I said
> a the outside, it is a preference for MT. I like to drive cars and
> the MT is more enjoyable than the ATs I have driven. I don't like it
> shifting when I don't want it to and I don't like the slippy feel of
> the torque converter. The fact that the MT is usually faster and more
> fuel efficient is a bonus.
check the modern civics in that department.
>
>
>>>>> It is like a slipping clutch. As for more
>>>>> torque (horsepower really) a lot of that is eaten up by the
>>>>> inefficiency of the torque converter.
>>>> how is a slipping clutch more efficient? [it's not.]
>>> No, I understand that (unlike a slipping clutch) there is a benefit to
>>> the slip designed into the AT. I just don't like the feel of it and
>>> the benefit is more than eaten up by the inefficiencies that come with
>>> it.
>> you'd hate cvt. there's no "relationship" between revs and engine speed
>> at all.
>
> I think you are probably right. That is why I mentioned the fact that
> the CVT isn't very popular in the US (if anywhere) and I think it is
> because lots of people hate it. Why else would Honda sell a 7-speed
> CVT?
because they rely on dealer feedback, and dealers are morons? cvt was
pretty popular in europe iirc. volvo sold them as well as daf, and they
did quite well.
>
> OTOH, it probably appeals to - or at least doesn't repulse - the
> hybrid buyer because it befits the unconventional nature of the car. I
> realize there are technical benefits to the combination of hybrid and
> CVT, but I am saying that the unconventional nature of the CVT is less
> of a negative when you are already committed to buying an
> unconventional vehicle. If you are attracted to the hybrid because it
> is unconventional, the CVT is a plus.
nah, it's a pure engineering logic decision. cvt allows extremely good
engine efficiency. if you don't want that, you don't want a hybrid.
>
>>>>> On cars where you can get a MT
>>>>> or AT with the same engine, the MT is almost always faster and gets
>>>>> better mileage.
>>>> not so with the modern autos. and that's one of the big things about
>>>> honda autos - it's basically a standard transmission with clutch packs
>>>> instead of synchros. inherently more efficient than planetary gears.
>>> Looking at the differences between the ATs in the econo cars tested by
>>> CR, Honda looks about as good as the other ATs (except for the CVT.)
>> you're looking at fuel economy, right?
>
> Fuel economy was significantly better for the MTs but the biggest
> difference was acceleration. The MTs blew the doors off the ATs. In
> terms of 0 - 60 time differences, the Yaris AT was the best - "only"
> 2.1 seconds slower than the MT version. Even the slowest MT car, the
> Kia Rio was faster than the Versa CVT. The fastest AT car, the Yaris,
> was 1.4 seconds slower than the Versa CVT.
dude, compare like with like - not different car to different car if
you're trying to compare trnasmissions, i.e. yaris with cvt, yaris with
stick, etc. yaris stick to versa cvt doesn't work.
>
>>>>>>> The ultimate "torque multiplier" is a CVT.
>>>>>> that's different - it's not a torque multiplier.
>>>>> Neither is the conventional AT, it just has a clever design to let the
>>>>> engine speed up ahead of the vehicle speed without shifting. It is
>>>>> basically like a limited range CVT.
>>>> no dude, they're totally different. "torque multiplier" is something a
>>>> torque converter can do - hence its name. everything else is ratio
>>>> control, be it continuously variable or discrete.
>>> OK, explain it to me. My understanding is that it is just a trick to
>>> get the engine running at a slightly higher rpm to produce more power.
>>> Kind of like a mini downshift. All car transmissions are torque
>>> multipliers.
>> ok, yes, but we're talking about different things. torque converters
>> can increase torque output from a little to a lot in a very limited rev
>> range. ratio change is something different and that's what the gears
>> are for.
>
> You understand that the ATs torque output at a certain rpm (i.e. power
> transmitted) is higher when the torque multiplication is active. There
> are only two way this can happen. The first is to increase the
> efficiency of the transmission. I think we can dismiss that. The
> other way is to increase the power input.
no, it depends on input/output speed differential. within certain rev
ranges, torque transmission is very high, even with a rev differential.
if it gets outside of that band, it drops right off.
> The only way to do that is
> to increase the throttle opening or increase the rpm. The throttle
> opening is determined by your foot (and it wouldn't be much of a trick
> for the torque multiplier to be just an extra jerk on the throttle and
> it wouldn't do much good if the throttle were already wide open.)
> However, rpm is largely controlled by the transmission. The
> transmission allows the engine to run a little faster and therefore
> produce more power which is transmitted to the wheels. This is what I
> meant by a mini downshift.
that's the lockup clutch releasing.
>
>>> They take high rpm/low torque and turn it into low rpm
>>> high torque. If it were perfectly efficient, the power output would
>>> be equal to input but of course it is always less. No way to get more
>>> power out unless you put more power in, i.e. run the engine at higher
>>> rpm.
>> see above.
>>
>>>>>> if is however a great
>>>>>> way of achieving absolute optimum gear for all conditions.
>>>>> I agree that it has a big theoretical advantage, especially compared
>>>>> to a conventional AT.
>>>> compared to /any/ transmission. there are mechanical efficiency issues
>>>> with the friction interface, but that is more than outweighed by ratio
>>>> flexibility and ability to keep the engine at its most efficient.
>>> The why doesn't the Versa with a CVT get better mileage or accelerate
>>> faster than the Versa with an MT? Unfortunately, there are few cars
>>> which allow you to directly compare CVT vs. MT.
>> civic hx was significantly more fuel efficient than the stick.
>
> I gather that was the CVT-equipped model. They don't sell it anymore.
> I guess people hated it more than high fuel costs.
my money's on dealer prejudice, not consumer. by the same token, the
hatchback has been all but dropped in the u.s. afaikt, that's more to
do with vehicles with the same utility selling for $30k rather than $15k
for a hatch, not consumer demand. try buying a used hatchback civic
here in the bay area - good luck! people just keep them - they never
sell.
>
>>>>>>> A lot of people don't like
>>>>>>> them at all, but others say they get used to it. (The perception
>>>>>>> problem is so bad that some manufacturers program virtual gears into
>>>>>>> them thereby defeating the chief advantage of the CVT.)
>>>>>> absolutely! i drove a "real" cvt one when i was in europe years ago,
>>>>>> and yes it is /real/ weird at first. but it's amazing how much you can
>>>>>> get out of a small 2-cylinder engine when it's got perfect gearing.
>>>>>> quite fun! this particular model had 2 independent drives too, so not
>>>>>> only did you have optimum gearing, you had limited slip diff benefits in
>>>>>> snow & ice too.
>>>>>> http://www.ritzsite.demon.nl/DAF/DAF_cars_p2.htm
>>>>> That was the original CVT. Do you remember who offered the first CVT
>>>>> in the US. (I don't think they ever sold the Daffodil here.)
>>>> subaru?
>>> That is what I recall. The car was called the Justy.
>>>
>>>>>>> I only rode
>>>>>>> in one CVT car, a Nissan luxury sedan in Japan and it wasn't bad in
>>>>>>> that application. He drove it fairly aggressively too - we hit almost
>>>>>>> 180 kph on the expressway. I would like to try one of these. I don't
>>>>>>> know if I would like it or not.
>>>>>> if you're not used to traditional automatics, the transition is easy.
>>>>>> if you're used to traditional autos, its weird for a few minutes because
>>>>>> it doesn't "shift", but beyond that, they're actually very impressive.
>>>>> Again though, I am not sure they are any faster or more efficient than
>>>>> a good MT.
>>>> well, the daf was only 650cc iirc, and 0-30, that wasn't much to touch it.
>>> I think the Honda 600 would have blown its petals off. ;-)
>>>
>>>>> Consumer Reports tested the Versa with MT and with CVT.
>>>>> The MT version was 0.6 seconds faster to 60 and got one more mpg. (And
>>>>> CR panned that MT.) They also tested MT and (conventional) AT
>>>>> versions of Fit, Rio, Accent and Yaris. In each case the MT was 2 - 3
>>>>> seconds faster and got 2 more mpg, so the CVT was clearly better than
>>>>> an AT but not as good as even a mediocre MT, at last on raw numbers.
>>>> that depends on the management system. the modern cvt's "simulate" gear
>>>> shifts which is the dumbest damned thing since it's not utilizing the
>>>> inherent benefit of the system! on that basis, i'm not surprised.
>>> Does the Versa do that? CR didn't mention it.
>> don't know. given "consumer demand", i expect so.
>
> Like I said, they hate it just like you think I would. (Actually I
> would love to try one, I do think it is a neat idea and it would be
> fun for a while at least. Only after the novelty wore off could I
> tell you if I like it or hate it. I actually suspect that I would
> like it more than a conventional AT.)
>
> Here is an interesting review I found. (It indicates that the Versa
> CVT does not have "gears," so the fact that it was slower and less
> fuel efficient than the "clunky" MT is significant.) I made one
> editorial comment in brackets.
>
> --quote--
> But the CVT is the one that shines. Its proprietary design, benefiting
> from Nissan's global cooperation with French carmaker Renault, is
> uncanny in the way it maintains optimal engine rpm within the most
> fuel-efficient torque range. It senses, for example, when the Versa is
> proceeding downhill and glides effortlessly into a lower gear range to
> slow the car with engine braking. [What if you don't want engine
> braking? It is wasting kinetic energy = fuel.
not correct. when engine braking, fuel delivery is completely stopped.
> What it needs in a
> powerful computer with optical sensors to look ahead, evaluate the
> situation and decide whether engine braking is advantageous
why? i don't want my car making /that/ kind of decision. seriously,
auto engine braking only happens when you're foot braking - just like on
a stick. you can't criticize what you've not used dude.
>.]
> Conversely, under pedal-to-the-floor acceleration, the CVT instantly
> launches the engine to its max-torque rpm, then keeps it there
> unchanged until a desired highway speed is reached.
>
> This goes against every traditional sensation of driving, wherein gear
> changes trigger a momentary drop in rpm as the higher gear ratio is
> engaged. There's a lot of mechanical inefficiency in that traditional
> gear-change syncopation; and Versa's CVT eliminates it. When first
> experiencing the CVT's behavior, it feels wrong, sounds noisy. In
> truth, however, it's mostly the lack of noticeable gear changes that's
> merely thwarting a driver's subconscious expectation of rising-falling
> rpms as gears change.
> --end quote--
>
> http://www.carlist.com/newcars/2007/ncr1116.html
>
>
>>>>> And yet, there is hardly a proliferation of CVTs on the market. Most
>>>>> of them seem to be on hybrids in fact.
>>>> that's consumer and mechanic inertia - nothing to do with benefits or
>>>> reliability. trust me on that one - i've driven the daf for an extended
>>>> period and it's a great system.
>>> Maybe. I would gladly trade the AT in my Ody for one if it was proven
>>> reliable. Not all are. The on in the Saturn Vue was a disaster, but
>>> I guess you have to expect that from GM. The Japanese units don't
>>> seem to have any problems.
>> i've never heard of problems with the civic hx.
>
> Neither have I, but then there aren't a lot out there.
/all/ the 96-2000 hx autos are cvt.
> On Mon, 08 Jan 2007 21:25:13 -0800, jim beam
> <spamvortex@bad.example.net> wrote:
>
>> Gordon McGrew wrote:
>>> On Sun, 07 Jan 2007 15:20:11 -0800, jim beam
>>> <spamvortex@bad.example.net> wrote:
>>>
>>>>>>>>> The problem with most (virtually all) ATs is that they are biased
>>>>>>>>> toward automatic operation and discourage manual operation.
>>>>>>>> how? my auto has the shift in exactly the same place as where the stick
>>>>>>>> would be. i see no difference. the transmission even has a no-lock
>>>>>>>> gate between 3rd & 4th [commonest manual override] especially so you
>>>>>>>> /can/ flip up and down at will.
>>>>>>> If you put it in 4, will it ever downshift into 3 by itself?
>>>>>> yes, absolutely. it does it on "kickdown" acceleration /and/ it does it
>>>>>> on braking. not gentle braking, but harder braking.
>>>>> It is not a bad thing, I just don't care for it. If I want to
>>>>> downshift, I can do that. If I don't want to, I don't like the car
>>>>> doing it on its own.
>>>> why not? it's just like you'd have on a stick.
>>> Not sure I understand. My GS-R never downshifts on its own.
>> if it doesn't, then there's something wrong. how old is it?
>
> It is a '94 with a 5-speed manual transmission. What kind of MT cars
> have you driven that shift themselves???
i misunderstood you.
originally, you said "If I want to downshift, I can do that." well, you
can on an auto. on my car, the shifter is in the same place as a stick
would be too. and the auto replicates engine braking when you need it -
just like you'd do yourself. really, it's a good system.
>
>
>>>>>>> When you
>>>>>>> shift into 3 does it effectively double clutch?
>>>>>> pointless exercise on an automatic. but even then, on the modern autos,
>>>>>> in conjunction with electronic throttle, yes, the engine revs /are/
>>>>>> meshed to the gear on shift.
>>>>> That is what I mean. I figured they had fixed that aspect which is
>>>>> the worst part of the older ATs.
>>>>>
>>>>>>>>> Also, I
>>>>>>>>> don't particularly care for the slippage of the torque converter.
>>>>>>>> eh? what "slippage" is that? how does its mechanical function differ
>>>>>>> >from a clutch [other than it has a much better efficiency range and is
>>>>>>>> much smoother of course]?
>>>>>>> Well, as you point out, I don't have any experience with modern high
>>>>>>> end luxury cars, but I note that at least more modest cars generally
>>>>>>> have a significantly greater 0-60 speed and a lower mpg rating. Since
>>>>>>> they now mostly have five gears, I would assume that means they are
>>>>>>> slipping.
>>>>>> there's no slipping unless the lock-up clutch is released. see below.
>>>>>>
>>>>>>> Actually, the slipping is partly by design, the so-called
>>>>>>> torque multiplier effect.
>>>>>> yes, that's what a torque converter does.
>>>>>>
>>>>>>> Basically, if you are cruising along and
>>>>>>> you give it a little gas, but not enough to force a downshift, you
>>>>>>> will see the rpms jump up immediately.
>>>>>> that's because the lockup clutch is released to allow more torque. more
>>>>>> flexibility than a stick where you'd have to shift.
>>>>> But that is the slippage. The engine speeds up races up ahead of any
>>>>> change in vehicle speed.
>>>> but i don't understand the problem - what's wrong with it? engines are
>>>> not perfect across all rev ranges - why not let a computer manage the
>>>> efficiency curves - for that's what's happening.
>>> It is just a personal preference. I like the engine to be positively
>>> coupled to the wheels.
>> that's what the lockup clutch in the torque converter is for.
>
> But it isn't engaged all the time. When it disengages, that is when
> it "slips" and I do not find that satisfying as a driver.
you'd hate cvt. as i said before, there's zero relation between engine
speed and vehicle speed - if you drive on engine revs, and it sounds
like you do, you'll be suffering total loss of feedback.
> Like I said
> a the outside, it is a preference for MT. I like to drive cars and
> the MT is more enjoyable than the ATs I have driven. I don't like it
> shifting when I don't want it to and I don't like the slippy feel of
> the torque converter. The fact that the MT is usually faster and more
> fuel efficient is a bonus.
check the modern civics in that department.
>
>
>>>>> It is like a slipping clutch. As for more
>>>>> torque (horsepower really) a lot of that is eaten up by the
>>>>> inefficiency of the torque converter.
>>>> how is a slipping clutch more efficient? [it's not.]
>>> No, I understand that (unlike a slipping clutch) there is a benefit to
>>> the slip designed into the AT. I just don't like the feel of it and
>>> the benefit is more than eaten up by the inefficiencies that come with
>>> it.
>> you'd hate cvt. there's no "relationship" between revs and engine speed
>> at all.
>
> I think you are probably right. That is why I mentioned the fact that
> the CVT isn't very popular in the US (if anywhere) and I think it is
> because lots of people hate it. Why else would Honda sell a 7-speed
> CVT?
because they rely on dealer feedback, and dealers are morons? cvt was
pretty popular in europe iirc. volvo sold them as well as daf, and they
did quite well.
>
> OTOH, it probably appeals to - or at least doesn't repulse - the
> hybrid buyer because it befits the unconventional nature of the car. I
> realize there are technical benefits to the combination of hybrid and
> CVT, but I am saying that the unconventional nature of the CVT is less
> of a negative when you are already committed to buying an
> unconventional vehicle. If you are attracted to the hybrid because it
> is unconventional, the CVT is a plus.
nah, it's a pure engineering logic decision. cvt allows extremely good
engine efficiency. if you don't want that, you don't want a hybrid.
>
>>>>> On cars where you can get a MT
>>>>> or AT with the same engine, the MT is almost always faster and gets
>>>>> better mileage.
>>>> not so with the modern autos. and that's one of the big things about
>>>> honda autos - it's basically a standard transmission with clutch packs
>>>> instead of synchros. inherently more efficient than planetary gears.
>>> Looking at the differences between the ATs in the econo cars tested by
>>> CR, Honda looks about as good as the other ATs (except for the CVT.)
>> you're looking at fuel economy, right?
>
> Fuel economy was significantly better for the MTs but the biggest
> difference was acceleration. The MTs blew the doors off the ATs. In
> terms of 0 - 60 time differences, the Yaris AT was the best - "only"
> 2.1 seconds slower than the MT version. Even the slowest MT car, the
> Kia Rio was faster than the Versa CVT. The fastest AT car, the Yaris,
> was 1.4 seconds slower than the Versa CVT.
dude, compare like with like - not different car to different car if
you're trying to compare trnasmissions, i.e. yaris with cvt, yaris with
stick, etc. yaris stick to versa cvt doesn't work.
>
>>>>>>> The ultimate "torque multiplier" is a CVT.
>>>>>> that's different - it's not a torque multiplier.
>>>>> Neither is the conventional AT, it just has a clever design to let the
>>>>> engine speed up ahead of the vehicle speed without shifting. It is
>>>>> basically like a limited range CVT.
>>>> no dude, they're totally different. "torque multiplier" is something a
>>>> torque converter can do - hence its name. everything else is ratio
>>>> control, be it continuously variable or discrete.
>>> OK, explain it to me. My understanding is that it is just a trick to
>>> get the engine running at a slightly higher rpm to produce more power.
>>> Kind of like a mini downshift. All car transmissions are torque
>>> multipliers.
>> ok, yes, but we're talking about different things. torque converters
>> can increase torque output from a little to a lot in a very limited rev
>> range. ratio change is something different and that's what the gears
>> are for.
>
> You understand that the ATs torque output at a certain rpm (i.e. power
> transmitted) is higher when the torque multiplication is active. There
> are only two way this can happen. The first is to increase the
> efficiency of the transmission. I think we can dismiss that. The
> other way is to increase the power input.
no, it depends on input/output speed differential. within certain rev
ranges, torque transmission is very high, even with a rev differential.
if it gets outside of that band, it drops right off.
> The only way to do that is
> to increase the throttle opening or increase the rpm. The throttle
> opening is determined by your foot (and it wouldn't be much of a trick
> for the torque multiplier to be just an extra jerk on the throttle and
> it wouldn't do much good if the throttle were already wide open.)
> However, rpm is largely controlled by the transmission. The
> transmission allows the engine to run a little faster and therefore
> produce more power which is transmitted to the wheels. This is what I
> meant by a mini downshift.
that's the lockup clutch releasing.
>
>>> They take high rpm/low torque and turn it into low rpm
>>> high torque. If it were perfectly efficient, the power output would
>>> be equal to input but of course it is always less. No way to get more
>>> power out unless you put more power in, i.e. run the engine at higher
>>> rpm.
>> see above.
>>
>>>>>> if is however a great
>>>>>> way of achieving absolute optimum gear for all conditions.
>>>>> I agree that it has a big theoretical advantage, especially compared
>>>>> to a conventional AT.
>>>> compared to /any/ transmission. there are mechanical efficiency issues
>>>> with the friction interface, but that is more than outweighed by ratio
>>>> flexibility and ability to keep the engine at its most efficient.
>>> The why doesn't the Versa with a CVT get better mileage or accelerate
>>> faster than the Versa with an MT? Unfortunately, there are few cars
>>> which allow you to directly compare CVT vs. MT.
>> civic hx was significantly more fuel efficient than the stick.
>
> I gather that was the CVT-equipped model. They don't sell it anymore.
> I guess people hated it more than high fuel costs.
my money's on dealer prejudice, not consumer. by the same token, the
hatchback has been all but dropped in the u.s. afaikt, that's more to
do with vehicles with the same utility selling for $30k rather than $15k
for a hatch, not consumer demand. try buying a used hatchback civic
here in the bay area - good luck! people just keep them - they never
sell.
>
>>>>>>> A lot of people don't like
>>>>>>> them at all, but others say they get used to it. (The perception
>>>>>>> problem is so bad that some manufacturers program virtual gears into
>>>>>>> them thereby defeating the chief advantage of the CVT.)
>>>>>> absolutely! i drove a "real" cvt one when i was in europe years ago,
>>>>>> and yes it is /real/ weird at first. but it's amazing how much you can
>>>>>> get out of a small 2-cylinder engine when it's got perfect gearing.
>>>>>> quite fun! this particular model had 2 independent drives too, so not
>>>>>> only did you have optimum gearing, you had limited slip diff benefits in
>>>>>> snow & ice too.
>>>>>> http://www.ritzsite.demon.nl/DAF/DAF_cars_p2.htm
>>>>> That was the original CVT. Do you remember who offered the first CVT
>>>>> in the US. (I don't think they ever sold the Daffodil here.)
>>>> subaru?
>>> That is what I recall. The car was called the Justy.
>>>
>>>>>>> I only rode
>>>>>>> in one CVT car, a Nissan luxury sedan in Japan and it wasn't bad in
>>>>>>> that application. He drove it fairly aggressively too - we hit almost
>>>>>>> 180 kph on the expressway. I would like to try one of these. I don't
>>>>>>> know if I would like it or not.
>>>>>> if you're not used to traditional automatics, the transition is easy.
>>>>>> if you're used to traditional autos, its weird for a few minutes because
>>>>>> it doesn't "shift", but beyond that, they're actually very impressive.
>>>>> Again though, I am not sure they are any faster or more efficient than
>>>>> a good MT.
>>>> well, the daf was only 650cc iirc, and 0-30, that wasn't much to touch it.
>>> I think the Honda 600 would have blown its petals off. ;-)
>>>
>>>>> Consumer Reports tested the Versa with MT and with CVT.
>>>>> The MT version was 0.6 seconds faster to 60 and got one more mpg. (And
>>>>> CR panned that MT.) They also tested MT and (conventional) AT
>>>>> versions of Fit, Rio, Accent and Yaris. In each case the MT was 2 - 3
>>>>> seconds faster and got 2 more mpg, so the CVT was clearly better than
>>>>> an AT but not as good as even a mediocre MT, at last on raw numbers.
>>>> that depends on the management system. the modern cvt's "simulate" gear
>>>> shifts which is the dumbest damned thing since it's not utilizing the
>>>> inherent benefit of the system! on that basis, i'm not surprised.
>>> Does the Versa do that? CR didn't mention it.
>> don't know. given "consumer demand", i expect so.
>
> Like I said, they hate it just like you think I would. (Actually I
> would love to try one, I do think it is a neat idea and it would be
> fun for a while at least. Only after the novelty wore off could I
> tell you if I like it or hate it. I actually suspect that I would
> like it more than a conventional AT.)
>
> Here is an interesting review I found. (It indicates that the Versa
> CVT does not have "gears," so the fact that it was slower and less
> fuel efficient than the "clunky" MT is significant.) I made one
> editorial comment in brackets.
>
> --quote--
> But the CVT is the one that shines. Its proprietary design, benefiting
> from Nissan's global cooperation with French carmaker Renault, is
> uncanny in the way it maintains optimal engine rpm within the most
> fuel-efficient torque range. It senses, for example, when the Versa is
> proceeding downhill and glides effortlessly into a lower gear range to
> slow the car with engine braking. [What if you don't want engine
> braking? It is wasting kinetic energy = fuel.
not correct. when engine braking, fuel delivery is completely stopped.
> What it needs in a
> powerful computer with optical sensors to look ahead, evaluate the
> situation and decide whether engine braking is advantageous
why? i don't want my car making /that/ kind of decision. seriously,
auto engine braking only happens when you're foot braking - just like on
a stick. you can't criticize what you've not used dude.
>.]
> Conversely, under pedal-to-the-floor acceleration, the CVT instantly
> launches the engine to its max-torque rpm, then keeps it there
> unchanged until a desired highway speed is reached.
>
> This goes against every traditional sensation of driving, wherein gear
> changes trigger a momentary drop in rpm as the higher gear ratio is
> engaged. There's a lot of mechanical inefficiency in that traditional
> gear-change syncopation; and Versa's CVT eliminates it. When first
> experiencing the CVT's behavior, it feels wrong, sounds noisy. In
> truth, however, it's mostly the lack of noticeable gear changes that's
> merely thwarting a driver's subconscious expectation of rising-falling
> rpms as gears change.
> --end quote--
>
> http://www.carlist.com/newcars/2007/ncr1116.html
>
>
>>>>> And yet, there is hardly a proliferation of CVTs on the market. Most
>>>>> of them seem to be on hybrids in fact.
>>>> that's consumer and mechanic inertia - nothing to do with benefits or
>>>> reliability. trust me on that one - i've driven the daf for an extended
>>>> period and it's a great system.
>>> Maybe. I would gladly trade the AT in my Ody for one if it was proven
>>> reliable. Not all are. The on in the Saturn Vue was a disaster, but
>>> I guess you have to expect that from GM. The Japanese units don't
>>> seem to have any problems.
>> i've never heard of problems with the civic hx.
>
> Neither have I, but then there aren't a lot out there.
/all/ the 96-2000 hx autos are cvt.
01-10-2007 | 11:43 PM
#93
Guest
Posts: n/a
Re: Transmission Activity
Gordon McGrew wrote:
> On Mon, 08 Jan 2007 21:25:13 -0800, jim beam
> <spamvortex@bad.example.net> wrote:
>
>> Gordon McGrew wrote:
>>> On Sun, 07 Jan 2007 15:20:11 -0800, jim beam
>>> <spamvortex@bad.example.net> wrote:
>>>
>>>>>>>>> The problem with most (virtually all) ATs is that they are biased
>>>>>>>>> toward automatic operation and discourage manual operation.
>>>>>>>> how? my auto has the shift in exactly the same place as where the stick
>>>>>>>> would be. i see no difference. the transmission even has a no-lock
>>>>>>>> gate between 3rd & 4th [commonest manual override] especially so you
>>>>>>>> /can/ flip up and down at will.
>>>>>>> If you put it in 4, will it ever downshift into 3 by itself?
>>>>>> yes, absolutely. it does it on "kickdown" acceleration /and/ it does it
>>>>>> on braking. not gentle braking, but harder braking.
>>>>> It is not a bad thing, I just don't care for it. If I want to
>>>>> downshift, I can do that. If I don't want to, I don't like the car
>>>>> doing it on its own.
>>>> why not? it's just like you'd have on a stick.
>>> Not sure I understand. My GS-R never downshifts on its own.
>> if it doesn't, then there's something wrong. how old is it?
>
> It is a '94 with a 5-speed manual transmission. What kind of MT cars
> have you driven that shift themselves???
i misunderstood you.
originally, you said "If I want to downshift, I can do that." well, you
can on an auto. on my car, the shifter is in the same place as a stick
would be too. and the auto replicates engine braking when you need it -
just like you'd do yourself. really, it's a good system.
>
>
>>>>>>> When you
>>>>>>> shift into 3 does it effectively double clutch?
>>>>>> pointless exercise on an automatic. but even then, on the modern autos,
>>>>>> in conjunction with electronic throttle, yes, the engine revs /are/
>>>>>> meshed to the gear on shift.
>>>>> That is what I mean. I figured they had fixed that aspect which is
>>>>> the worst part of the older ATs.
>>>>>
>>>>>>>>> Also, I
>>>>>>>>> don't particularly care for the slippage of the torque converter.
>>>>>>>> eh? what "slippage" is that? how does its mechanical function differ
>>>>>>> >from a clutch [other than it has a much better efficiency range and is
>>>>>>>> much smoother of course]?
>>>>>>> Well, as you point out, I don't have any experience with modern high
>>>>>>> end luxury cars, but I note that at least more modest cars generally
>>>>>>> have a significantly greater 0-60 speed and a lower mpg rating. Since
>>>>>>> they now mostly have five gears, I would assume that means they are
>>>>>>> slipping.
>>>>>> there's no slipping unless the lock-up clutch is released. see below.
>>>>>>
>>>>>>> Actually, the slipping is partly by design, the so-called
>>>>>>> torque multiplier effect.
>>>>>> yes, that's what a torque converter does.
>>>>>>
>>>>>>> Basically, if you are cruising along and
>>>>>>> you give it a little gas, but not enough to force a downshift, you
>>>>>>> will see the rpms jump up immediately.
>>>>>> that's because the lockup clutch is released to allow more torque. more
>>>>>> flexibility than a stick where you'd have to shift.
>>>>> But that is the slippage. The engine speeds up races up ahead of any
>>>>> change in vehicle speed.
>>>> but i don't understand the problem - what's wrong with it? engines are
>>>> not perfect across all rev ranges - why not let a computer manage the
>>>> efficiency curves - for that's what's happening.
>>> It is just a personal preference. I like the engine to be positively
>>> coupled to the wheels.
>> that's what the lockup clutch in the torque converter is for.
>
> But it isn't engaged all the time. When it disengages, that is when
> it "slips" and I do not find that satisfying as a driver.
you'd hate cvt. as i said before, there's zero relation between engine
speed and vehicle speed - if you drive on engine revs, and it sounds
like you do, you'll be suffering total loss of feedback.
> Like I said
> a the outside, it is a preference for MT. I like to drive cars and
> the MT is more enjoyable than the ATs I have driven. I don't like it
> shifting when I don't want it to and I don't like the slippy feel of
> the torque converter. The fact that the MT is usually faster and more
> fuel efficient is a bonus.
check the modern civics in that department.
>
>
>>>>> It is like a slipping clutch. As for more
>>>>> torque (horsepower really) a lot of that is eaten up by the
>>>>> inefficiency of the torque converter.
>>>> how is a slipping clutch more efficient? [it's not.]
>>> No, I understand that (unlike a slipping clutch) there is a benefit to
>>> the slip designed into the AT. I just don't like the feel of it and
>>> the benefit is more than eaten up by the inefficiencies that come with
>>> it.
>> you'd hate cvt. there's no "relationship" between revs and engine speed
>> at all.
>
> I think you are probably right. That is why I mentioned the fact that
> the CVT isn't very popular in the US (if anywhere) and I think it is
> because lots of people hate it. Why else would Honda sell a 7-speed
> CVT?
because they rely on dealer feedback, and dealers are morons? cvt was
pretty popular in europe iirc. volvo sold them as well as daf, and they
did quite well.
>
> OTOH, it probably appeals to - or at least doesn't repulse - the
> hybrid buyer because it befits the unconventional nature of the car. I
> realize there are technical benefits to the combination of hybrid and
> CVT, but I am saying that the unconventional nature of the CVT is less
> of a negative when you are already committed to buying an
> unconventional vehicle. If you are attracted to the hybrid because it
> is unconventional, the CVT is a plus.
nah, it's a pure engineering logic decision. cvt allows extremely good
engine efficiency. if you don't want that, you don't want a hybrid.
>
>>>>> On cars where you can get a MT
>>>>> or AT with the same engine, the MT is almost always faster and gets
>>>>> better mileage.
>>>> not so with the modern autos. and that's one of the big things about
>>>> honda autos - it's basically a standard transmission with clutch packs
>>>> instead of synchros. inherently more efficient than planetary gears.
>>> Looking at the differences between the ATs in the econo cars tested by
>>> CR, Honda looks about as good as the other ATs (except for the CVT.)
>> you're looking at fuel economy, right?
>
> Fuel economy was significantly better for the MTs but the biggest
> difference was acceleration. The MTs blew the doors off the ATs. In
> terms of 0 - 60 time differences, the Yaris AT was the best - "only"
> 2.1 seconds slower than the MT version. Even the slowest MT car, the
> Kia Rio was faster than the Versa CVT. The fastest AT car, the Yaris,
> was 1.4 seconds slower than the Versa CVT.
dude, compare like with like - not different car to different car if
you're trying to compare trnasmissions, i.e. yaris with cvt, yaris with
stick, etc. yaris stick to versa cvt doesn't work.
>
>>>>>>> The ultimate "torque multiplier" is a CVT.
>>>>>> that's different - it's not a torque multiplier.
>>>>> Neither is the conventional AT, it just has a clever design to let the
>>>>> engine speed up ahead of the vehicle speed without shifting. It is
>>>>> basically like a limited range CVT.
>>>> no dude, they're totally different. "torque multiplier" is something a
>>>> torque converter can do - hence its name. everything else is ratio
>>>> control, be it continuously variable or discrete.
>>> OK, explain it to me. My understanding is that it is just a trick to
>>> get the engine running at a slightly higher rpm to produce more power.
>>> Kind of like a mini downshift. All car transmissions are torque
>>> multipliers.
>> ok, yes, but we're talking about different things. torque converters
>> can increase torque output from a little to a lot in a very limited rev
>> range. ratio change is something different and that's what the gears
>> are for.
>
> You understand that the ATs torque output at a certain rpm (i.e. power
> transmitted) is higher when the torque multiplication is active. There
> are only two way this can happen. The first is to increase the
> efficiency of the transmission. I think we can dismiss that. The
> other way is to increase the power input.
no, it depends on input/output speed differential. within certain rev
ranges, torque transmission is very high, even with a rev differential.
if it gets outside of that band, it drops right off.
> The only way to do that is
> to increase the throttle opening or increase the rpm. The throttle
> opening is determined by your foot (and it wouldn't be much of a trick
> for the torque multiplier to be just an extra jerk on the throttle and
> it wouldn't do much good if the throttle were already wide open.)
> However, rpm is largely controlled by the transmission. The
> transmission allows the engine to run a little faster and therefore
> produce more power which is transmitted to the wheels. This is what I
> meant by a mini downshift.
that's the lockup clutch releasing.
>
>>> They take high rpm/low torque and turn it into low rpm
>>> high torque. If it were perfectly efficient, the power output would
>>> be equal to input but of course it is always less. No way to get more
>>> power out unless you put more power in, i.e. run the engine at higher
>>> rpm.
>> see above.
>>
>>>>>> if is however a great
>>>>>> way of achieving absolute optimum gear for all conditions.
>>>>> I agree that it has a big theoretical advantage, especially compared
>>>>> to a conventional AT.
>>>> compared to /any/ transmission. there are mechanical efficiency issues
>>>> with the friction interface, but that is more than outweighed by ratio
>>>> flexibility and ability to keep the engine at its most efficient.
>>> The why doesn't the Versa with a CVT get better mileage or accelerate
>>> faster than the Versa with an MT? Unfortunately, there are few cars
>>> which allow you to directly compare CVT vs. MT.
>> civic hx was significantly more fuel efficient than the stick.
>
> I gather that was the CVT-equipped model. They don't sell it anymore.
> I guess people hated it more than high fuel costs.
my money's on dealer prejudice, not consumer. by the same token, the
hatchback has been all but dropped in the u.s. afaikt, that's more to
do with vehicles with the same utility selling for $30k rather than $15k
for a hatch, not consumer demand. try buying a used hatchback civic
here in the bay area - good luck! people just keep them - they never
sell.
>
>>>>>>> A lot of people don't like
>>>>>>> them at all, but others say they get used to it. (The perception
>>>>>>> problem is so bad that some manufacturers program virtual gears into
>>>>>>> them thereby defeating the chief advantage of the CVT.)
>>>>>> absolutely! i drove a "real" cvt one when i was in europe years ago,
>>>>>> and yes it is /real/ weird at first. but it's amazing how much you can
>>>>>> get out of a small 2-cylinder engine when it's got perfect gearing.
>>>>>> quite fun! this particular model had 2 independent drives too, so not
>>>>>> only did you have optimum gearing, you had limited slip diff benefits in
>>>>>> snow & ice too.
>>>>>> http://www.ritzsite.demon.nl/DAF/DAF_cars_p2.htm
>>>>> That was the original CVT. Do you remember who offered the first CVT
>>>>> in the US. (I don't think they ever sold the Daffodil here.)
>>>> subaru?
>>> That is what I recall. The car was called the Justy.
>>>
>>>>>>> I only rode
>>>>>>> in one CVT car, a Nissan luxury sedan in Japan and it wasn't bad in
>>>>>>> that application. He drove it fairly aggressively too - we hit almost
>>>>>>> 180 kph on the expressway. I would like to try one of these. I don't
>>>>>>> know if I would like it or not.
>>>>>> if you're not used to traditional automatics, the transition is easy.
>>>>>> if you're used to traditional autos, its weird for a few minutes because
>>>>>> it doesn't "shift", but beyond that, they're actually very impressive.
>>>>> Again though, I am not sure they are any faster or more efficient than
>>>>> a good MT.
>>>> well, the daf was only 650cc iirc, and 0-30, that wasn't much to touch it.
>>> I think the Honda 600 would have blown its petals off. ;-)
>>>
>>>>> Consumer Reports tested the Versa with MT and with CVT.
>>>>> The MT version was 0.6 seconds faster to 60 and got one more mpg. (And
>>>>> CR panned that MT.) They also tested MT and (conventional) AT
>>>>> versions of Fit, Rio, Accent and Yaris. In each case the MT was 2 - 3
>>>>> seconds faster and got 2 more mpg, so the CVT was clearly better than
>>>>> an AT but not as good as even a mediocre MT, at last on raw numbers.
>>>> that depends on the management system. the modern cvt's "simulate" gear
>>>> shifts which is the dumbest damned thing since it's not utilizing the
>>>> inherent benefit of the system! on that basis, i'm not surprised.
>>> Does the Versa do that? CR didn't mention it.
>> don't know. given "consumer demand", i expect so.
>
> Like I said, they hate it just like you think I would. (Actually I
> would love to try one, I do think it is a neat idea and it would be
> fun for a while at least. Only after the novelty wore off could I
> tell you if I like it or hate it. I actually suspect that I would
> like it more than a conventional AT.)
>
> Here is an interesting review I found. (It indicates that the Versa
> CVT does not have "gears," so the fact that it was slower and less
> fuel efficient than the "clunky" MT is significant.) I made one
> editorial comment in brackets.
>
> --quote--
> But the CVT is the one that shines. Its proprietary design, benefiting
> from Nissan's global cooperation with French carmaker Renault, is
> uncanny in the way it maintains optimal engine rpm within the most
> fuel-efficient torque range. It senses, for example, when the Versa is
> proceeding downhill and glides effortlessly into a lower gear range to
> slow the car with engine braking. [What if you don't want engine
> braking? It is wasting kinetic energy = fuel.
not correct. when engine braking, fuel delivery is completely stopped.
> What it needs in a
> powerful computer with optical sensors to look ahead, evaluate the
> situation and decide whether engine braking is advantageous
why? i don't want my car making /that/ kind of decision. seriously,
auto engine braking only happens when you're foot braking - just like on
a stick. you can't criticize what you've not used dude.
>.]
> Conversely, under pedal-to-the-floor acceleration, the CVT instantly
> launches the engine to its max-torque rpm, then keeps it there
> unchanged until a desired highway speed is reached.
>
> This goes against every traditional sensation of driving, wherein gear
> changes trigger a momentary drop in rpm as the higher gear ratio is
> engaged. There's a lot of mechanical inefficiency in that traditional
> gear-change syncopation; and Versa's CVT eliminates it. When first
> experiencing the CVT's behavior, it feels wrong, sounds noisy. In
> truth, however, it's mostly the lack of noticeable gear changes that's
> merely thwarting a driver's subconscious expectation of rising-falling
> rpms as gears change.
> --end quote--
>
> http://www.carlist.com/newcars/2007/ncr1116.html
>
>
>>>>> And yet, there is hardly a proliferation of CVTs on the market. Most
>>>>> of them seem to be on hybrids in fact.
>>>> that's consumer and mechanic inertia - nothing to do with benefits or
>>>> reliability. trust me on that one - i've driven the daf for an extended
>>>> period and it's a great system.
>>> Maybe. I would gladly trade the AT in my Ody for one if it was proven
>>> reliable. Not all are. The on in the Saturn Vue was a disaster, but
>>> I guess you have to expect that from GM. The Japanese units don't
>>> seem to have any problems.
>> i've never heard of problems with the civic hx.
>
> Neither have I, but then there aren't a lot out there.
/all/ the 96-2000 hx autos are cvt.
> On Mon, 08 Jan 2007 21:25:13 -0800, jim beam
> <spamvortex@bad.example.net> wrote:
>
>> Gordon McGrew wrote:
>>> On Sun, 07 Jan 2007 15:20:11 -0800, jim beam
>>> <spamvortex@bad.example.net> wrote:
>>>
>>>>>>>>> The problem with most (virtually all) ATs is that they are biased
>>>>>>>>> toward automatic operation and discourage manual operation.
>>>>>>>> how? my auto has the shift in exactly the same place as where the stick
>>>>>>>> would be. i see no difference. the transmission even has a no-lock
>>>>>>>> gate between 3rd & 4th [commonest manual override] especially so you
>>>>>>>> /can/ flip up and down at will.
>>>>>>> If you put it in 4, will it ever downshift into 3 by itself?
>>>>>> yes, absolutely. it does it on "kickdown" acceleration /and/ it does it
>>>>>> on braking. not gentle braking, but harder braking.
>>>>> It is not a bad thing, I just don't care for it. If I want to
>>>>> downshift, I can do that. If I don't want to, I don't like the car
>>>>> doing it on its own.
>>>> why not? it's just like you'd have on a stick.
>>> Not sure I understand. My GS-R never downshifts on its own.
>> if it doesn't, then there's something wrong. how old is it?
>
> It is a '94 with a 5-speed manual transmission. What kind of MT cars
> have you driven that shift themselves???
i misunderstood you.
originally, you said "If I want to downshift, I can do that." well, you
can on an auto. on my car, the shifter is in the same place as a stick
would be too. and the auto replicates engine braking when you need it -
just like you'd do yourself. really, it's a good system.
>
>
>>>>>>> When you
>>>>>>> shift into 3 does it effectively double clutch?
>>>>>> pointless exercise on an automatic. but even then, on the modern autos,
>>>>>> in conjunction with electronic throttle, yes, the engine revs /are/
>>>>>> meshed to the gear on shift.
>>>>> That is what I mean. I figured they had fixed that aspect which is
>>>>> the worst part of the older ATs.
>>>>>
>>>>>>>>> Also, I
>>>>>>>>> don't particularly care for the slippage of the torque converter.
>>>>>>>> eh? what "slippage" is that? how does its mechanical function differ
>>>>>>> >from a clutch [other than it has a much better efficiency range and is
>>>>>>>> much smoother of course]?
>>>>>>> Well, as you point out, I don't have any experience with modern high
>>>>>>> end luxury cars, but I note that at least more modest cars generally
>>>>>>> have a significantly greater 0-60 speed and a lower mpg rating. Since
>>>>>>> they now mostly have five gears, I would assume that means they are
>>>>>>> slipping.
>>>>>> there's no slipping unless the lock-up clutch is released. see below.
>>>>>>
>>>>>>> Actually, the slipping is partly by design, the so-called
>>>>>>> torque multiplier effect.
>>>>>> yes, that's what a torque converter does.
>>>>>>
>>>>>>> Basically, if you are cruising along and
>>>>>>> you give it a little gas, but not enough to force a downshift, you
>>>>>>> will see the rpms jump up immediately.
>>>>>> that's because the lockup clutch is released to allow more torque. more
>>>>>> flexibility than a stick where you'd have to shift.
>>>>> But that is the slippage. The engine speeds up races up ahead of any
>>>>> change in vehicle speed.
>>>> but i don't understand the problem - what's wrong with it? engines are
>>>> not perfect across all rev ranges - why not let a computer manage the
>>>> efficiency curves - for that's what's happening.
>>> It is just a personal preference. I like the engine to be positively
>>> coupled to the wheels.
>> that's what the lockup clutch in the torque converter is for.
>
> But it isn't engaged all the time. When it disengages, that is when
> it "slips" and I do not find that satisfying as a driver.
you'd hate cvt. as i said before, there's zero relation between engine
speed and vehicle speed - if you drive on engine revs, and it sounds
like you do, you'll be suffering total loss of feedback.
> Like I said
> a the outside, it is a preference for MT. I like to drive cars and
> the MT is more enjoyable than the ATs I have driven. I don't like it
> shifting when I don't want it to and I don't like the slippy feel of
> the torque converter. The fact that the MT is usually faster and more
> fuel efficient is a bonus.
check the modern civics in that department.
>
>
>>>>> It is like a slipping clutch. As for more
>>>>> torque (horsepower really) a lot of that is eaten up by the
>>>>> inefficiency of the torque converter.
>>>> how is a slipping clutch more efficient? [it's not.]
>>> No, I understand that (unlike a slipping clutch) there is a benefit to
>>> the slip designed into the AT. I just don't like the feel of it and
>>> the benefit is more than eaten up by the inefficiencies that come with
>>> it.
>> you'd hate cvt. there's no "relationship" between revs and engine speed
>> at all.
>
> I think you are probably right. That is why I mentioned the fact that
> the CVT isn't very popular in the US (if anywhere) and I think it is
> because lots of people hate it. Why else would Honda sell a 7-speed
> CVT?
because they rely on dealer feedback, and dealers are morons? cvt was
pretty popular in europe iirc. volvo sold them as well as daf, and they
did quite well.
>
> OTOH, it probably appeals to - or at least doesn't repulse - the
> hybrid buyer because it befits the unconventional nature of the car. I
> realize there are technical benefits to the combination of hybrid and
> CVT, but I am saying that the unconventional nature of the CVT is less
> of a negative when you are already committed to buying an
> unconventional vehicle. If you are attracted to the hybrid because it
> is unconventional, the CVT is a plus.
nah, it's a pure engineering logic decision. cvt allows extremely good
engine efficiency. if you don't want that, you don't want a hybrid.
>
>>>>> On cars where you can get a MT
>>>>> or AT with the same engine, the MT is almost always faster and gets
>>>>> better mileage.
>>>> not so with the modern autos. and that's one of the big things about
>>>> honda autos - it's basically a standard transmission with clutch packs
>>>> instead of synchros. inherently more efficient than planetary gears.
>>> Looking at the differences between the ATs in the econo cars tested by
>>> CR, Honda looks about as good as the other ATs (except for the CVT.)
>> you're looking at fuel economy, right?
>
> Fuel economy was significantly better for the MTs but the biggest
> difference was acceleration. The MTs blew the doors off the ATs. In
> terms of 0 - 60 time differences, the Yaris AT was the best - "only"
> 2.1 seconds slower than the MT version. Even the slowest MT car, the
> Kia Rio was faster than the Versa CVT. The fastest AT car, the Yaris,
> was 1.4 seconds slower than the Versa CVT.
dude, compare like with like - not different car to different car if
you're trying to compare trnasmissions, i.e. yaris with cvt, yaris with
stick, etc. yaris stick to versa cvt doesn't work.
>
>>>>>>> The ultimate "torque multiplier" is a CVT.
>>>>>> that's different - it's not a torque multiplier.
>>>>> Neither is the conventional AT, it just has a clever design to let the
>>>>> engine speed up ahead of the vehicle speed without shifting. It is
>>>>> basically like a limited range CVT.
>>>> no dude, they're totally different. "torque multiplier" is something a
>>>> torque converter can do - hence its name. everything else is ratio
>>>> control, be it continuously variable or discrete.
>>> OK, explain it to me. My understanding is that it is just a trick to
>>> get the engine running at a slightly higher rpm to produce more power.
>>> Kind of like a mini downshift. All car transmissions are torque
>>> multipliers.
>> ok, yes, but we're talking about different things. torque converters
>> can increase torque output from a little to a lot in a very limited rev
>> range. ratio change is something different and that's what the gears
>> are for.
>
> You understand that the ATs torque output at a certain rpm (i.e. power
> transmitted) is higher when the torque multiplication is active. There
> are only two way this can happen. The first is to increase the
> efficiency of the transmission. I think we can dismiss that. The
> other way is to increase the power input.
no, it depends on input/output speed differential. within certain rev
ranges, torque transmission is very high, even with a rev differential.
if it gets outside of that band, it drops right off.
> The only way to do that is
> to increase the throttle opening or increase the rpm. The throttle
> opening is determined by your foot (and it wouldn't be much of a trick
> for the torque multiplier to be just an extra jerk on the throttle and
> it wouldn't do much good if the throttle were already wide open.)
> However, rpm is largely controlled by the transmission. The
> transmission allows the engine to run a little faster and therefore
> produce more power which is transmitted to the wheels. This is what I
> meant by a mini downshift.
that's the lockup clutch releasing.
>
>>> They take high rpm/low torque and turn it into low rpm
>>> high torque. If it were perfectly efficient, the power output would
>>> be equal to input but of course it is always less. No way to get more
>>> power out unless you put more power in, i.e. run the engine at higher
>>> rpm.
>> see above.
>>
>>>>>> if is however a great
>>>>>> way of achieving absolute optimum gear for all conditions.
>>>>> I agree that it has a big theoretical advantage, especially compared
>>>>> to a conventional AT.
>>>> compared to /any/ transmission. there are mechanical efficiency issues
>>>> with the friction interface, but that is more than outweighed by ratio
>>>> flexibility and ability to keep the engine at its most efficient.
>>> The why doesn't the Versa with a CVT get better mileage or accelerate
>>> faster than the Versa with an MT? Unfortunately, there are few cars
>>> which allow you to directly compare CVT vs. MT.
>> civic hx was significantly more fuel efficient than the stick.
>
> I gather that was the CVT-equipped model. They don't sell it anymore.
> I guess people hated it more than high fuel costs.
my money's on dealer prejudice, not consumer. by the same token, the
hatchback has been all but dropped in the u.s. afaikt, that's more to
do with vehicles with the same utility selling for $30k rather than $15k
for a hatch, not consumer demand. try buying a used hatchback civic
here in the bay area - good luck! people just keep them - they never
sell.
>
>>>>>>> A lot of people don't like
>>>>>>> them at all, but others say they get used to it. (The perception
>>>>>>> problem is so bad that some manufacturers program virtual gears into
>>>>>>> them thereby defeating the chief advantage of the CVT.)
>>>>>> absolutely! i drove a "real" cvt one when i was in europe years ago,
>>>>>> and yes it is /real/ weird at first. but it's amazing how much you can
>>>>>> get out of a small 2-cylinder engine when it's got perfect gearing.
>>>>>> quite fun! this particular model had 2 independent drives too, so not
>>>>>> only did you have optimum gearing, you had limited slip diff benefits in
>>>>>> snow & ice too.
>>>>>> http://www.ritzsite.demon.nl/DAF/DAF_cars_p2.htm
>>>>> That was the original CVT. Do you remember who offered the first CVT
>>>>> in the US. (I don't think they ever sold the Daffodil here.)
>>>> subaru?
>>> That is what I recall. The car was called the Justy.
>>>
>>>>>>> I only rode
>>>>>>> in one CVT car, a Nissan luxury sedan in Japan and it wasn't bad in
>>>>>>> that application. He drove it fairly aggressively too - we hit almost
>>>>>>> 180 kph on the expressway. I would like to try one of these. I don't
>>>>>>> know if I would like it or not.
>>>>>> if you're not used to traditional automatics, the transition is easy.
>>>>>> if you're used to traditional autos, its weird for a few minutes because
>>>>>> it doesn't "shift", but beyond that, they're actually very impressive.
>>>>> Again though, I am not sure they are any faster or more efficient than
>>>>> a good MT.
>>>> well, the daf was only 650cc iirc, and 0-30, that wasn't much to touch it.
>>> I think the Honda 600 would have blown its petals off. ;-)
>>>
>>>>> Consumer Reports tested the Versa with MT and with CVT.
>>>>> The MT version was 0.6 seconds faster to 60 and got one more mpg. (And
>>>>> CR panned that MT.) They also tested MT and (conventional) AT
>>>>> versions of Fit, Rio, Accent and Yaris. In each case the MT was 2 - 3
>>>>> seconds faster and got 2 more mpg, so the CVT was clearly better than
>>>>> an AT but not as good as even a mediocre MT, at last on raw numbers.
>>>> that depends on the management system. the modern cvt's "simulate" gear
>>>> shifts which is the dumbest damned thing since it's not utilizing the
>>>> inherent benefit of the system! on that basis, i'm not surprised.
>>> Does the Versa do that? CR didn't mention it.
>> don't know. given "consumer demand", i expect so.
>
> Like I said, they hate it just like you think I would. (Actually I
> would love to try one, I do think it is a neat idea and it would be
> fun for a while at least. Only after the novelty wore off could I
> tell you if I like it or hate it. I actually suspect that I would
> like it more than a conventional AT.)
>
> Here is an interesting review I found. (It indicates that the Versa
> CVT does not have "gears," so the fact that it was slower and less
> fuel efficient than the "clunky" MT is significant.) I made one
> editorial comment in brackets.
>
> --quote--
> But the CVT is the one that shines. Its proprietary design, benefiting
> from Nissan's global cooperation with French carmaker Renault, is
> uncanny in the way it maintains optimal engine rpm within the most
> fuel-efficient torque range. It senses, for example, when the Versa is
> proceeding downhill and glides effortlessly into a lower gear range to
> slow the car with engine braking. [What if you don't want engine
> braking? It is wasting kinetic energy = fuel.
not correct. when engine braking, fuel delivery is completely stopped.
> What it needs in a
> powerful computer with optical sensors to look ahead, evaluate the
> situation and decide whether engine braking is advantageous
why? i don't want my car making /that/ kind of decision. seriously,
auto engine braking only happens when you're foot braking - just like on
a stick. you can't criticize what you've not used dude.
>.]
> Conversely, under pedal-to-the-floor acceleration, the CVT instantly
> launches the engine to its max-torque rpm, then keeps it there
> unchanged until a desired highway speed is reached.
>
> This goes against every traditional sensation of driving, wherein gear
> changes trigger a momentary drop in rpm as the higher gear ratio is
> engaged. There's a lot of mechanical inefficiency in that traditional
> gear-change syncopation; and Versa's CVT eliminates it. When first
> experiencing the CVT's behavior, it feels wrong, sounds noisy. In
> truth, however, it's mostly the lack of noticeable gear changes that's
> merely thwarting a driver's subconscious expectation of rising-falling
> rpms as gears change.
> --end quote--
>
> http://www.carlist.com/newcars/2007/ncr1116.html
>
>
>>>>> And yet, there is hardly a proliferation of CVTs on the market. Most
>>>>> of them seem to be on hybrids in fact.
>>>> that's consumer and mechanic inertia - nothing to do with benefits or
>>>> reliability. trust me on that one - i've driven the daf for an extended
>>>> period and it's a great system.
>>> Maybe. I would gladly trade the AT in my Ody for one if it was proven
>>> reliable. Not all are. The on in the Saturn Vue was a disaster, but
>>> I guess you have to expect that from GM. The Japanese units don't
>>> seem to have any problems.
>> i've never heard of problems with the civic hx.
>
> Neither have I, but then there aren't a lot out there.
/all/ the 96-2000 hx autos are cvt.
01-12-2007 | 12:50 AM
#94
Guest
Posts: n/a
Re: Transmission Activity
On Wed, 10 Jan 2007 20:43:45 -0800, jim beam
<spamvortex@bad.example.net> wrote:
>Gordon McGrew wrote:
>> On Mon, 08 Jan 2007 21:25:13 -0800, jim beam
>> <spamvortex@bad.example.net> wrote:
>>
>>> Gordon McGrew wrote:
>>>> On Sun, 07 Jan 2007 15:20:11 -0800, jim beam
>>>> <spamvortex@bad.example.net> wrote:
>>>>
>>>>>>>>>> The problem with most (virtually all) ATs is that they are biased
>>>>>>>>>> toward automatic operation and discourage manual operation.
>>>>>>>>> how? my auto has the shift in exactly the same place as where the stick
>>>>>>>>> would be. i see no difference. the transmission even has a no-lock
>>>>>>>>> gate between 3rd & 4th [commonest manual override] especially so you
>>>>>>>>> /can/ flip up and down at will.
>>>>>>>> If you put it in 4, will it ever downshift into 3 by itself?
>>>>>>> yes, absolutely. it does it on "kickdown" acceleration /and/ it does it
>>>>>>> on braking. not gentle braking, but harder braking.
>>>>>> It is not a bad thing, I just don't care for it. If I want to
>>>>>> downshift, I can do that. If I don't want to, I don't like the car
>>>>>> doing it on its own.
>>>>> why not? it's just like you'd have on a stick.
>>>> Not sure I understand. My GS-R never downshifts on its own.
>>> if it doesn't, then there's something wrong. how old is it?
>>
>> It is a '94 with a 5-speed manual transmission. What kind of MT cars
>> have you driven that shift themselves???
>
>i misunderstood you.
>
>originally, you said "If I want to downshift, I can do that." well, you
>can on an auto. on my car, the shifter is in the same place as a stick
>would be too. and the auto replicates engine braking when you need it -
>just like you'd do yourself. really, it's a good system.
>
>>
>>
>>>>>>>> When you
>>>>>>>> shift into 3 does it effectively double clutch?
>>>>>>> pointless exercise on an automatic. but even then, on the modern autos,
>>>>>>> in conjunction with electronic throttle, yes, the engine revs /are/
>>>>>>> meshed to the gear on shift.
>>>>>> That is what I mean. I figured they had fixed that aspect which is
>>>>>> the worst part of the older ATs.
>>>>>>
>>>>>>>>>> Also, I
>>>>>>>>>> don't particularly care for the slippage of the torque converter.
>>>>>>>>> eh? what "slippage" is that? how does its mechanical function differ
>>>>>>>> >from a clutch [other than it has a much better efficiency range and is
>>>>>>>>> much smoother of course]?
>>>>>>>> Well, as you point out, I don't have any experience with modern high
>>>>>>>> end luxury cars, but I note that at least more modest cars generally
>>>>>>>> have a significantly greater 0-60 speed and a lower mpg rating. Since
>>>>>>>> they now mostly have five gears, I would assume that means they are
>>>>>>>> slipping.
>>>>>>> there's no slipping unless the lock-up clutch is released. see below.
>>>>>>>
>>>>>>>> Actually, the slipping is partly by design, the so-called
>>>>>>>> torque multiplier effect.
>>>>>>> yes, that's what a torque converter does.
>>>>>>>
>>>>>>>> Basically, if you are cruising along and
>>>>>>>> you give it a little gas, but not enough to force a downshift, you
>>>>>>>> will see the rpms jump up immediately.
>>>>>>> that's because the lockup clutch is released to allow more torque. more
>>>>>>> flexibility than a stick where you'd have to shift.
>>>>>> But that is the slippage. The engine speeds up races up ahead of any
>>>>>> change in vehicle speed.
>>>>> but i don't understand the problem - what's wrong with it? engines are
>>>>> not perfect across all rev ranges - why not let a computer manage the
>>>>> efficiency curves - for that's what's happening.
>>>> It is just a personal preference. I like the engine to be positively
>>>> coupled to the wheels.
>>> that's what the lockup clutch in the torque converter is for.
>>
>> But it isn't engaged all the time. When it disengages, that is when
>> it "slips" and I do not find that satisfying as a driver.
>
>you'd hate cvt. as i said before, there's zero relation between engine
>speed and vehicle speed - if you drive on engine revs, and it sounds
>like you do, you'll be suffering total loss of feedback.
>
>> Like I said
>> a the outside, it is a preference for MT. I like to drive cars and
>> the MT is more enjoyable than the ATs I have driven. I don't like it
>> shifting when I don't want it to and I don't like the slippy feel of
>> the torque converter. The fact that the MT is usually faster and more
>> fuel efficient is a bonus.
>
>check the modern civics in that department.
The AT Civic gets slightly better highway mileage than the MT - I am
guessing it may have a higher final ratio. The Accord 4 and V6 and
the Fit all get better mileage with the MT. I don't have any test
results, but I bet the MTs are universally faster (see below.)
>>>>>> It is like a slipping clutch. As for more
>>>>>> torque (horsepower really) a lot of that is eaten up by the
>>>>>> inefficiency of the torque converter.
>>>>> how is a slipping clutch more efficient? [it's not.]
>>>> No, I understand that (unlike a slipping clutch) there is a benefit to
>>>> the slip designed into the AT. I just don't like the feel of it and
>>>> the benefit is more than eaten up by the inefficiencies that come with
>>>> it.
>>> you'd hate cvt. there's no "relationship" between revs and engine speed
>>> at all.
>>
>> I think you are probably right. That is why I mentioned the fact that
>> the CVT isn't very popular in the US (if anywhere) and I think it is
>> because lots of people hate it. Why else would Honda sell a 7-speed
>> CVT?
>
>because they rely on dealer feedback, and dealers are morons? cvt was
>pretty popular in europe iirc. volvo sold them as well as daf, and they
>did quite well.
Why is that in the past tense? We agree they are more efficient than
conventional ATs and if they were popular, why didn't they drive
conventional ATs off the market? Reliability could have been an issue
but shouldn't be now (as long as you stay away form GM.)
>>
>> OTOH, it probably appeals to - or at least doesn't repulse - the
>> hybrid buyer because it befits the unconventional nature of the car. I
>> realize there are technical benefits to the combination of hybrid and
>> CVT, but I am saying that the unconventional nature of the CVT is less
>> of a negative when you are already committed to buying an
>> unconventional vehicle. If you are attracted to the hybrid because it
>> is unconventional, the CVT is a plus.
>
>nah, it's a pure engineering logic decision. cvt allows extremely good
>engine efficiency. if you don't want that, you don't want a hybrid.
Exactly right. The converse of that statement is that, if you want
increased efficiency, you will tolerate or even embrace the CVT. And
if you like the hybrid because it is odd or technologically advanced,
then you will love the CVT.
>>>>>> On cars where you can get a MT
>>>>>> or AT with the same engine, the MT is almost always faster and gets
>>>>>> better mileage.
>>>>> not so with the modern autos. and that's one of the big things about
>>>>> honda autos - it's basically a standard transmission with clutch packs
>>>>> instead of synchros. inherently more efficient than planetary gears.
>>>> Looking at the differences between the ATs in the econo cars tested by
>>>> CR, Honda looks about as good as the other ATs (except for the CVT.)
>>> you're looking at fuel economy, right?
>>
>> Fuel economy was significantly better for the MTs but the biggest
>> difference was acceleration. The MTs blew the doors off the ATs. In
>> terms of 0 - 60 time differences, the Yaris AT was the best - "only"
>> 2.1 seconds slower than the MT version. Even the slowest MT car, the
>> Kia Rio was faster than the Versa CVT. The fastest AT car, the Yaris,
>> was 1.4 seconds slower than the Versa CVT.
>
>dude, compare like with like - not different car to different car if
>you're trying to compare trnasmissions, i.e. yaris with cvt, yaris with
>stick, etc. yaris stick to versa cvt doesn't work.
It doesn't matter whether you compare like to like or unlike to like.
All of the MTs are faster than all of the ATs and the CVT. Let me
tabulate it for you:
0-60 45-65 1/4 mi
Fit AT 12.4 8.4 19.0
Fit MT 9.9 6.5 17.4
Versa CVT 10.1 6.4 17.8
Versa MT 9.5 5.9 17.2
Rio AT 12.8 8.1 19.3
Rio MT 10.0 7.1 17.5
Accent AT 12.5 7.7 19.1
Accent MT 9.5 6.5 17.2
Yaris AT 11.4 6.9 18.6
Yaris MT 9.3 6.0 17.3
As I said, "The MTs blew the doors off the ATs."
>
>>
>>>>>>>> The ultimate "torque multiplier" is a CVT.
>>>>>>> that's different - it's not a torque multiplier.
>>>>>> Neither is the conventional AT, it just has a clever design to let the
>>>>>> engine speed up ahead of the vehicle speed without shifting. It is
>>>>>> basically like a limited range CVT.
>>>>> no dude, they're totally different. "torque multiplier" is something a
>>>>> torque converter can do - hence its name. everything else is ratio
>>>>> control, be it continuously variable or discrete.
>>>> OK, explain it to me. My understanding is that it is just a trick to
>>>> get the engine running at a slightly higher rpm to produce more power.
>>>> Kind of like a mini downshift. All car transmissions are torque
>>>> multipliers.
>>> ok, yes, but we're talking about different things. torque converters
>>> can increase torque output from a little to a lot in a very limited rev
>>> range. ratio change is something different and that's what the gears
>>> are for.
>>
>> You understand that the ATs torque output at a certain rpm (i.e. power
>> transmitted) is higher when the torque multiplication is active. There
>> are only two way this can happen. The first is to increase the
>> efficiency of the transmission. I think we can dismiss that. The
>> other way is to increase the power input.
>
>no, it depends on input/output speed differential. within certain rev
>ranges, torque transmission is very high, even with a rev differential.
> if it gets outside of that band, it drops right off.
http://en.wikipedia.org/wiki/Torque_...Multiplication
--quotes-- [my comments in brackets]
Unlike a fluid coupling, however, a torque converter is able to
multiply torque when there is a substantial difference between input
and output rotational speed, thus providing the equivalent of a
reduction gear. [IOW, a mini-downshift, a slightly lower gear that
allows the engine to run faster and produce more power.]
The principal difference is that whereas a fluid coupling is a two
element drive that is incapable of multiplying torque [IOW, it has a
1:1 ratio of input to output] , a torque converter has at least one
extra element - the stator - which alters the drive's characteristics
during periods of high slippage, producing an increase in output
torque. [IOW, it allows the engine to run faster and produce more
power, just like a lower gear.]
The Buick Dynaflow automatic transmission was a non-shifting design
and, under normal conditions, relied solely upon the converter to
multiply torque. [IOW, there was no gear transmission, all ratio
change was due to slippage of the TC - an early CVT!] The Dynaflow
used a five element converter to produce the wide range of torque
multiplication [i.e. wide range of drive ratios] needed to propel a
heavy vehicle.
* Acceleration. The load is accelerating but there still is a
relatively large difference between pump and turbine speed. [i.e. low
gear] ...The amount of multiplication will depend upon the actual
difference between pump and turbine speed, [i.e. the effective drive
ratio] as well as various other design factors. [efficiency]
* Coupling. The turbine has reached approximately 90 percent of
the speed of the pump. Torque multiplication has ceased [i.e. gear
ratio is slightly less than 1:1 but the slight power increase from
higher engine rpm is lost to inefficiency] and the torque converter is
behaving in a manner similar to a fluid coupling. In modern automotive
applications, it is usually at this stage of operation where the
lock-up clutch is applied, a procedure that tends to improve fuel
efficiency.
--end quotes--
When they say "torque multiplication" what they really mean is a drive
ratio less than 1:1. IOW, every transmission is a torque multiplier,
at least in the lower gears.
>
>> The only way to do that is
>> to increase the throttle opening or increase the rpm. The throttle
>> opening is determined by your foot (and it wouldn't be much of a trick
>> for the torque multiplier to be just an extra jerk on the throttle and
>> it wouldn't do much good if the throttle were already wide open.)
>> However, rpm is largely controlled by the transmission. The
>> transmission allows the engine to run a little faster and therefore
>> produce more power which is transmitted to the wheels. This is what I
>> meant by a mini downshift.
>
>that's the lockup clutch releasing.
Right, there is no torque multiplication in the TC unless it is
slipping.
>
>>
>>>> They take high rpm/low torque and turn it into low rpm
>>>> high torque. If it were perfectly efficient, the power output would
>>>> be equal to input but of course it is always less. No way to get more
>>>> power out unless you put more power in, i.e. run the engine at higher
>>>> rpm.
>>> see above.
>>>
>>>>>>> if is however a great
>>>>>>> way of achieving absolute optimum gear for all conditions.
>>>>>> I agree that it has a big theoretical advantage, especially compared
>>>>>> to a conventional AT.
>>>>> compared to /any/ transmission. there are mechanical efficiency issues
>>>>> with the friction interface, but that is more than outweighed by ratio
>>>>> flexibility and ability to keep the engine at its most efficient.
>>>> The why doesn't the Versa with a CVT get better mileage or accelerate
>>>> faster than the Versa with an MT? Unfortunately, there are few cars
>>>> which allow you to directly compare CVT vs. MT.
>>> civic hx was significantly more fuel efficient than the stick.
>>
>> I gather that was the CVT-equipped model. They don't sell it anymore.
>> I guess people hated it more than high fuel costs.
>
>my money's on dealer prejudice, not consumer. by the same token, the
>hatchback has been all but dropped in the u.s. afaikt, that's more to
>do with vehicles with the same utility selling for $30k rather than $15k
>for a hatch, not consumer demand. try buying a used hatchback civic
>here in the bay area - good luck! people just keep them - they never
>sell.
I personally like hatchbacks and I know they have a following. I too
am surprised and disappointed that they have all but disappeared. I
don't know I am ready to sign on to the conspiracy theory though. If
there were a strong market, Someone like Mazda or Nissan would jump to
serve it to increase their sales. apparently there isn't enough
demand to justify the high expense of two body styles and the sedan is
more popular.
I suppose I could blame the shortage of MTs on greedy dealers and
manufacturers who want to force me to buy a more expensive AT.
However, I am more inclined to blame Starbucks.
>>>>>>>> A lot of people don't like
>>>>>>>> them at all, but others say they get used to it. (The perception
>>>>>>>> problem is so bad that some manufacturers program virtual gears into
>>>>>>>> them thereby defeating the chief advantage of the CVT.)
>>>>>>> absolutely! i drove a "real" cvt one when i was in europe years ago,
>>>>>>> and yes it is /real/ weird at first. but it's amazing how much you can
>>>>>>> get out of a small 2-cylinder engine when it's got perfect gearing.
>>>>>>> quite fun! this particular model had 2 independent drives too, so not
>>>>>>> only did you have optimum gearing, you had limited slip diff benefits in
>>>>>>> snow & ice too.
>>>>>>> http://www.ritzsite.demon.nl/DAF/DAF_cars_p2.htm
>>>>>> That was the original CVT. Do you remember who offered the first CVT
>>>>>> in the US. (I don't think they ever sold the Daffodil here.)
>>>>> subaru?
>>>> That is what I recall. The car was called the Justy.
>>>>
>>>>>>>> I only rode
>>>>>>>> in one CVT car, a Nissan luxury sedan in Japan and it wasn't bad in
>>>>>>>> that application. He drove it fairly aggressively too - we hit almost
>>>>>>>> 180 kph on the expressway. I would like to try one of these. I don't
>>>>>>>> know if I would like it or not.
>>>>>>> if you're not used to traditional automatics, the transition is easy.
>>>>>>> if you're used to traditional autos, its weird for a few minutes because
>>>>>>> it doesn't "shift", but beyond that, they're actually very impressive.
>>>>>> Again though, I am not sure they are any faster or more efficient than
>>>>>> a good MT.
>>>>> well, the daf was only 650cc iirc, and 0-30, that wasn't much to touch it.
>>>> I think the Honda 600 would have blown its petals off. ;-)
>>>>
>>>>>> Consumer Reports tested the Versa with MT and with CVT.
>>>>>> The MT version was 0.6 seconds faster to 60 and got one more mpg. (And
>>>>>> CR panned that MT.) They also tested MT and (conventional) AT
>>>>>> versions of Fit, Rio, Accent and Yaris. In each case the MT was 2 - 3
>>>>>> seconds faster and got 2 more mpg, so the CVT was clearly better than
>>>>>> an AT but not as good as even a mediocre MT, at last on raw numbers.
>>>>> that depends on the management system. the modern cvt's "simulate" gear
>>>>> shifts which is the dumbest damned thing since it's not utilizing the
>>>>> inherent benefit of the system! on that basis, i'm not surprised.
>>>> Does the Versa do that? CR didn't mention it.
>>> don't know. given "consumer demand", i expect so.
>>
>> Like I said, they hate it just like you think I would. (Actually I
>> would love to try one, I do think it is a neat idea and it would be
>> fun for a while at least. Only after the novelty wore off could I
>> tell you if I like it or hate it. I actually suspect that I would
>> like it more than a conventional AT.)
>>
>> Here is an interesting review I found. (It indicates that the Versa
>> CVT does not have "gears," so the fact that it was slower and less
>> fuel efficient than the "clunky" MT is significant.) I made one
>> editorial comment in brackets.
>>
>> --quote--
>> But the CVT is the one that shines. Its proprietary design, benefiting
>> from Nissan's global cooperation with French carmaker Renault, is
>> uncanny in the way it maintains optimal engine rpm within the most
>> fuel-efficient torque range. It senses, for example, when the Versa is
>> proceeding downhill and glides effortlessly into a lower gear range to
>> slow the car with engine braking. [What if you don't want engine
>> braking? It is wasting kinetic energy = fuel.
>
>not correct. when engine braking, fuel delivery is completely stopped.
But kinetic energy is being lost. Doesn't matter if the car has to be
brought to a stop anyway, but if the driving situation requires little
or no compression braking and the computer orders a lot, the car will
slow unnecessarily and fuel will be consumed bringing it back up to
speed.
I use compression braking a lot. Sometimes I use a little, sometimes
I use a lot. Sometimes I coast with the clutch disengaged for maximum
distance. A transmission that always applies medium compression
braking is not as going to achieve the same thing.
>> What it needs in a
>> powerful computer with optical sensors to look ahead, evaluate the
>> situation and decide whether engine braking is advantageous
>
>why? i don't want my car making /that/ kind of decision. seriously,
But you are satisfied with it making the decision mindlessly. I agree
I do not want the car making that decision. I want to make it myself
and shift the transmission accordingly. My brain is the powerful
computer and my eyes are the optical sensors.
>auto engine braking only happens when you're foot braking - just like on
>a stick.
Not true. I use compression braking all the time with my foot off the
brake. Descending grades would be a prime example except that I live
in Chicago and there are no hills. Instead, I am the only guy in
crawling rush hour traffic not flashing his brake lights every 20
feet. It is way more fun than an AT if you play the game.
>you can't criticize what you've not used dude.
I am only pointing out that this feature has a down side. It might
not bother 95% of drivers, but it would bother me.
>
>>.]
>> Conversely, under pedal-to-the-floor acceleration, the CVT instantly
>> launches the engine to its max-torque rpm, then keeps it there
>> unchanged until a desired highway speed is reached.
>>
>> This goes against every traditional sensation of driving, wherein gear
>> changes trigger a momentary drop in rpm as the higher gear ratio is
>> engaged. There's a lot of mechanical inefficiency in that traditional
>> gear-change syncopation; and Versa's CVT eliminates it. When first
>> experiencing the CVT's behavior, it feels wrong, sounds noisy. In
>> truth, however, it's mostly the lack of noticeable gear changes that's
>> merely thwarting a driver's subconscious expectation of rising-falling
>> rpms as gears change.
>> --end quote--
>>
>> http://www.carlist.com/newcars/2007/ncr1116.html
>>
>>
>>>>>> And yet, there is hardly a proliferation of CVTs on the market. Most
>>>>>> of them seem to be on hybrids in fact.
>>>>> that's consumer and mechanic inertia - nothing to do with benefits or
>>>>> reliability. trust me on that one - i've driven the daf for an extended
>>>>> period and it's a great system.
>>>> Maybe. I would gladly trade the AT in my Ody for one if it was proven
>>>> reliable. Not all are. The on in the Saturn Vue was a disaster, but
>>>> I guess you have to expect that from GM. The Japanese units don't
>>>> seem to have any problems.
>>> i've never heard of problems with the civic hx.
>>
>> Neither have I, but then there aren't a lot out there.
>
>/all/ the 96-2000 hx autos are cvt.
Yes, but how many is that? If they had sold that many, it would still
be on the market. Don't get me wrong, I don't think they are any less
reliable than a conventional Civic AT, but I don't think there are
enough out there to really know for sure. They certainly aren't
terrible like the GM CVT.
<spamvortex@bad.example.net> wrote:
>Gordon McGrew wrote:
>> On Mon, 08 Jan 2007 21:25:13 -0800, jim beam
>> <spamvortex@bad.example.net> wrote:
>>
>>> Gordon McGrew wrote:
>>>> On Sun, 07 Jan 2007 15:20:11 -0800, jim beam
>>>> <spamvortex@bad.example.net> wrote:
>>>>
>>>>>>>>>> The problem with most (virtually all) ATs is that they are biased
>>>>>>>>>> toward automatic operation and discourage manual operation.
>>>>>>>>> how? my auto has the shift in exactly the same place as where the stick
>>>>>>>>> would be. i see no difference. the transmission even has a no-lock
>>>>>>>>> gate between 3rd & 4th [commonest manual override] especially so you
>>>>>>>>> /can/ flip up and down at will.
>>>>>>>> If you put it in 4, will it ever downshift into 3 by itself?
>>>>>>> yes, absolutely. it does it on "kickdown" acceleration /and/ it does it
>>>>>>> on braking. not gentle braking, but harder braking.
>>>>>> It is not a bad thing, I just don't care for it. If I want to
>>>>>> downshift, I can do that. If I don't want to, I don't like the car
>>>>>> doing it on its own.
>>>>> why not? it's just like you'd have on a stick.
>>>> Not sure I understand. My GS-R never downshifts on its own.
>>> if it doesn't, then there's something wrong. how old is it?
>>
>> It is a '94 with a 5-speed manual transmission. What kind of MT cars
>> have you driven that shift themselves???
>
>i misunderstood you.
>
>originally, you said "If I want to downshift, I can do that." well, you
>can on an auto. on my car, the shifter is in the same place as a stick
>would be too. and the auto replicates engine braking when you need it -
>just like you'd do yourself. really, it's a good system.
>
>>
>>
>>>>>>>> When you
>>>>>>>> shift into 3 does it effectively double clutch?
>>>>>>> pointless exercise on an automatic. but even then, on the modern autos,
>>>>>>> in conjunction with electronic throttle, yes, the engine revs /are/
>>>>>>> meshed to the gear on shift.
>>>>>> That is what I mean. I figured they had fixed that aspect which is
>>>>>> the worst part of the older ATs.
>>>>>>
>>>>>>>>>> Also, I
>>>>>>>>>> don't particularly care for the slippage of the torque converter.
>>>>>>>>> eh? what "slippage" is that? how does its mechanical function differ
>>>>>>>> >from a clutch [other than it has a much better efficiency range and is
>>>>>>>>> much smoother of course]?
>>>>>>>> Well, as you point out, I don't have any experience with modern high
>>>>>>>> end luxury cars, but I note that at least more modest cars generally
>>>>>>>> have a significantly greater 0-60 speed and a lower mpg rating. Since
>>>>>>>> they now mostly have five gears, I would assume that means they are
>>>>>>>> slipping.
>>>>>>> there's no slipping unless the lock-up clutch is released. see below.
>>>>>>>
>>>>>>>> Actually, the slipping is partly by design, the so-called
>>>>>>>> torque multiplier effect.
>>>>>>> yes, that's what a torque converter does.
>>>>>>>
>>>>>>>> Basically, if you are cruising along and
>>>>>>>> you give it a little gas, but not enough to force a downshift, you
>>>>>>>> will see the rpms jump up immediately.
>>>>>>> that's because the lockup clutch is released to allow more torque. more
>>>>>>> flexibility than a stick where you'd have to shift.
>>>>>> But that is the slippage. The engine speeds up races up ahead of any
>>>>>> change in vehicle speed.
>>>>> but i don't understand the problem - what's wrong with it? engines are
>>>>> not perfect across all rev ranges - why not let a computer manage the
>>>>> efficiency curves - for that's what's happening.
>>>> It is just a personal preference. I like the engine to be positively
>>>> coupled to the wheels.
>>> that's what the lockup clutch in the torque converter is for.
>>
>> But it isn't engaged all the time. When it disengages, that is when
>> it "slips" and I do not find that satisfying as a driver.
>
>you'd hate cvt. as i said before, there's zero relation between engine
>speed and vehicle speed - if you drive on engine revs, and it sounds
>like you do, you'll be suffering total loss of feedback.
>
>> Like I said
>> a the outside, it is a preference for MT. I like to drive cars and
>> the MT is more enjoyable than the ATs I have driven. I don't like it
>> shifting when I don't want it to and I don't like the slippy feel of
>> the torque converter. The fact that the MT is usually faster and more
>> fuel efficient is a bonus.
>
>check the modern civics in that department.
The AT Civic gets slightly better highway mileage than the MT - I am
guessing it may have a higher final ratio. The Accord 4 and V6 and
the Fit all get better mileage with the MT. I don't have any test
results, but I bet the MTs are universally faster (see below.)
>>>>>> It is like a slipping clutch. As for more
>>>>>> torque (horsepower really) a lot of that is eaten up by the
>>>>>> inefficiency of the torque converter.
>>>>> how is a slipping clutch more efficient? [it's not.]
>>>> No, I understand that (unlike a slipping clutch) there is a benefit to
>>>> the slip designed into the AT. I just don't like the feel of it and
>>>> the benefit is more than eaten up by the inefficiencies that come with
>>>> it.
>>> you'd hate cvt. there's no "relationship" between revs and engine speed
>>> at all.
>>
>> I think you are probably right. That is why I mentioned the fact that
>> the CVT isn't very popular in the US (if anywhere) and I think it is
>> because lots of people hate it. Why else would Honda sell a 7-speed
>> CVT?
>
>because they rely on dealer feedback, and dealers are morons? cvt was
>pretty popular in europe iirc. volvo sold them as well as daf, and they
>did quite well.
Why is that in the past tense? We agree they are more efficient than
conventional ATs and if they were popular, why didn't they drive
conventional ATs off the market? Reliability could have been an issue
but shouldn't be now (as long as you stay away form GM.)
>>
>> OTOH, it probably appeals to - or at least doesn't repulse - the
>> hybrid buyer because it befits the unconventional nature of the car. I
>> realize there are technical benefits to the combination of hybrid and
>> CVT, but I am saying that the unconventional nature of the CVT is less
>> of a negative when you are already committed to buying an
>> unconventional vehicle. If you are attracted to the hybrid because it
>> is unconventional, the CVT is a plus.
>
>nah, it's a pure engineering logic decision. cvt allows extremely good
>engine efficiency. if you don't want that, you don't want a hybrid.
Exactly right. The converse of that statement is that, if you want
increased efficiency, you will tolerate or even embrace the CVT. And
if you like the hybrid because it is odd or technologically advanced,
then you will love the CVT.
>>>>>> On cars where you can get a MT
>>>>>> or AT with the same engine, the MT is almost always faster and gets
>>>>>> better mileage.
>>>>> not so with the modern autos. and that's one of the big things about
>>>>> honda autos - it's basically a standard transmission with clutch packs
>>>>> instead of synchros. inherently more efficient than planetary gears.
>>>> Looking at the differences between the ATs in the econo cars tested by
>>>> CR, Honda looks about as good as the other ATs (except for the CVT.)
>>> you're looking at fuel economy, right?
>>
>> Fuel economy was significantly better for the MTs but the biggest
>> difference was acceleration. The MTs blew the doors off the ATs. In
>> terms of 0 - 60 time differences, the Yaris AT was the best - "only"
>> 2.1 seconds slower than the MT version. Even the slowest MT car, the
>> Kia Rio was faster than the Versa CVT. The fastest AT car, the Yaris,
>> was 1.4 seconds slower than the Versa CVT.
>
>dude, compare like with like - not different car to different car if
>you're trying to compare trnasmissions, i.e. yaris with cvt, yaris with
>stick, etc. yaris stick to versa cvt doesn't work.
It doesn't matter whether you compare like to like or unlike to like.
All of the MTs are faster than all of the ATs and the CVT. Let me
tabulate it for you:
0-60 45-65 1/4 mi
Fit AT 12.4 8.4 19.0
Fit MT 9.9 6.5 17.4
Versa CVT 10.1 6.4 17.8
Versa MT 9.5 5.9 17.2
Rio AT 12.8 8.1 19.3
Rio MT 10.0 7.1 17.5
Accent AT 12.5 7.7 19.1
Accent MT 9.5 6.5 17.2
Yaris AT 11.4 6.9 18.6
Yaris MT 9.3 6.0 17.3
As I said, "The MTs blew the doors off the ATs."
>
>>
>>>>>>>> The ultimate "torque multiplier" is a CVT.
>>>>>>> that's different - it's not a torque multiplier.
>>>>>> Neither is the conventional AT, it just has a clever design to let the
>>>>>> engine speed up ahead of the vehicle speed without shifting. It is
>>>>>> basically like a limited range CVT.
>>>>> no dude, they're totally different. "torque multiplier" is something a
>>>>> torque converter can do - hence its name. everything else is ratio
>>>>> control, be it continuously variable or discrete.
>>>> OK, explain it to me. My understanding is that it is just a trick to
>>>> get the engine running at a slightly higher rpm to produce more power.
>>>> Kind of like a mini downshift. All car transmissions are torque
>>>> multipliers.
>>> ok, yes, but we're talking about different things. torque converters
>>> can increase torque output from a little to a lot in a very limited rev
>>> range. ratio change is something different and that's what the gears
>>> are for.
>>
>> You understand that the ATs torque output at a certain rpm (i.e. power
>> transmitted) is higher when the torque multiplication is active. There
>> are only two way this can happen. The first is to increase the
>> efficiency of the transmission. I think we can dismiss that. The
>> other way is to increase the power input.
>
>no, it depends on input/output speed differential. within certain rev
>ranges, torque transmission is very high, even with a rev differential.
> if it gets outside of that band, it drops right off.
http://en.wikipedia.org/wiki/Torque_...Multiplication
--quotes-- [my comments in brackets]
Unlike a fluid coupling, however, a torque converter is able to
multiply torque when there is a substantial difference between input
and output rotational speed, thus providing the equivalent of a
reduction gear. [IOW, a mini-downshift, a slightly lower gear that
allows the engine to run faster and produce more power.]
The principal difference is that whereas a fluid coupling is a two
element drive that is incapable of multiplying torque [IOW, it has a
1:1 ratio of input to output] , a torque converter has at least one
extra element - the stator - which alters the drive's characteristics
during periods of high slippage, producing an increase in output
torque. [IOW, it allows the engine to run faster and produce more
power, just like a lower gear.]
The Buick Dynaflow automatic transmission was a non-shifting design
and, under normal conditions, relied solely upon the converter to
multiply torque. [IOW, there was no gear transmission, all ratio
change was due to slippage of the TC - an early CVT!] The Dynaflow
used a five element converter to produce the wide range of torque
multiplication [i.e. wide range of drive ratios] needed to propel a
heavy vehicle.
* Acceleration. The load is accelerating but there still is a
relatively large difference between pump and turbine speed. [i.e. low
gear] ...The amount of multiplication will depend upon the actual
difference between pump and turbine speed, [i.e. the effective drive
ratio] as well as various other design factors. [efficiency]
* Coupling. The turbine has reached approximately 90 percent of
the speed of the pump. Torque multiplication has ceased [i.e. gear
ratio is slightly less than 1:1 but the slight power increase from
higher engine rpm is lost to inefficiency] and the torque converter is
behaving in a manner similar to a fluid coupling. In modern automotive
applications, it is usually at this stage of operation where the
lock-up clutch is applied, a procedure that tends to improve fuel
efficiency.
--end quotes--
When they say "torque multiplication" what they really mean is a drive
ratio less than 1:1. IOW, every transmission is a torque multiplier,
at least in the lower gears.
>
>> The only way to do that is
>> to increase the throttle opening or increase the rpm. The throttle
>> opening is determined by your foot (and it wouldn't be much of a trick
>> for the torque multiplier to be just an extra jerk on the throttle and
>> it wouldn't do much good if the throttle were already wide open.)
>> However, rpm is largely controlled by the transmission. The
>> transmission allows the engine to run a little faster and therefore
>> produce more power which is transmitted to the wheels. This is what I
>> meant by a mini downshift.
>
>that's the lockup clutch releasing.
Right, there is no torque multiplication in the TC unless it is
slipping.
>
>>
>>>> They take high rpm/low torque and turn it into low rpm
>>>> high torque. If it were perfectly efficient, the power output would
>>>> be equal to input but of course it is always less. No way to get more
>>>> power out unless you put more power in, i.e. run the engine at higher
>>>> rpm.
>>> see above.
>>>
>>>>>>> if is however a great
>>>>>>> way of achieving absolute optimum gear for all conditions.
>>>>>> I agree that it has a big theoretical advantage, especially compared
>>>>>> to a conventional AT.
>>>>> compared to /any/ transmission. there are mechanical efficiency issues
>>>>> with the friction interface, but that is more than outweighed by ratio
>>>>> flexibility and ability to keep the engine at its most efficient.
>>>> The why doesn't the Versa with a CVT get better mileage or accelerate
>>>> faster than the Versa with an MT? Unfortunately, there are few cars
>>>> which allow you to directly compare CVT vs. MT.
>>> civic hx was significantly more fuel efficient than the stick.
>>
>> I gather that was the CVT-equipped model. They don't sell it anymore.
>> I guess people hated it more than high fuel costs.
>
>my money's on dealer prejudice, not consumer. by the same token, the
>hatchback has been all but dropped in the u.s. afaikt, that's more to
>do with vehicles with the same utility selling for $30k rather than $15k
>for a hatch, not consumer demand. try buying a used hatchback civic
>here in the bay area - good luck! people just keep them - they never
>sell.
I personally like hatchbacks and I know they have a following. I too
am surprised and disappointed that they have all but disappeared. I
don't know I am ready to sign on to the conspiracy theory though. If
there were a strong market, Someone like Mazda or Nissan would jump to
serve it to increase their sales. apparently there isn't enough
demand to justify the high expense of two body styles and the sedan is
more popular.
I suppose I could blame the shortage of MTs on greedy dealers and
manufacturers who want to force me to buy a more expensive AT.
However, I am more inclined to blame Starbucks.
>>>>>>>> A lot of people don't like
>>>>>>>> them at all, but others say they get used to it. (The perception
>>>>>>>> problem is so bad that some manufacturers program virtual gears into
>>>>>>>> them thereby defeating the chief advantage of the CVT.)
>>>>>>> absolutely! i drove a "real" cvt one when i was in europe years ago,
>>>>>>> and yes it is /real/ weird at first. but it's amazing how much you can
>>>>>>> get out of a small 2-cylinder engine when it's got perfect gearing.
>>>>>>> quite fun! this particular model had 2 independent drives too, so not
>>>>>>> only did you have optimum gearing, you had limited slip diff benefits in
>>>>>>> snow & ice too.
>>>>>>> http://www.ritzsite.demon.nl/DAF/DAF_cars_p2.htm
>>>>>> That was the original CVT. Do you remember who offered the first CVT
>>>>>> in the US. (I don't think they ever sold the Daffodil here.)
>>>>> subaru?
>>>> That is what I recall. The car was called the Justy.
>>>>
>>>>>>>> I only rode
>>>>>>>> in one CVT car, a Nissan luxury sedan in Japan and it wasn't bad in
>>>>>>>> that application. He drove it fairly aggressively too - we hit almost
>>>>>>>> 180 kph on the expressway. I would like to try one of these. I don't
>>>>>>>> know if I would like it or not.
>>>>>>> if you're not used to traditional automatics, the transition is easy.
>>>>>>> if you're used to traditional autos, its weird for a few minutes because
>>>>>>> it doesn't "shift", but beyond that, they're actually very impressive.
>>>>>> Again though, I am not sure they are any faster or more efficient than
>>>>>> a good MT.
>>>>> well, the daf was only 650cc iirc, and 0-30, that wasn't much to touch it.
>>>> I think the Honda 600 would have blown its petals off. ;-)
>>>>
>>>>>> Consumer Reports tested the Versa with MT and with CVT.
>>>>>> The MT version was 0.6 seconds faster to 60 and got one more mpg. (And
>>>>>> CR panned that MT.) They also tested MT and (conventional) AT
>>>>>> versions of Fit, Rio, Accent and Yaris. In each case the MT was 2 - 3
>>>>>> seconds faster and got 2 more mpg, so the CVT was clearly better than
>>>>>> an AT but not as good as even a mediocre MT, at last on raw numbers.
>>>>> that depends on the management system. the modern cvt's "simulate" gear
>>>>> shifts which is the dumbest damned thing since it's not utilizing the
>>>>> inherent benefit of the system! on that basis, i'm not surprised.
>>>> Does the Versa do that? CR didn't mention it.
>>> don't know. given "consumer demand", i expect so.
>>
>> Like I said, they hate it just like you think I would. (Actually I
>> would love to try one, I do think it is a neat idea and it would be
>> fun for a while at least. Only after the novelty wore off could I
>> tell you if I like it or hate it. I actually suspect that I would
>> like it more than a conventional AT.)
>>
>> Here is an interesting review I found. (It indicates that the Versa
>> CVT does not have "gears," so the fact that it was slower and less
>> fuel efficient than the "clunky" MT is significant.) I made one
>> editorial comment in brackets.
>>
>> --quote--
>> But the CVT is the one that shines. Its proprietary design, benefiting
>> from Nissan's global cooperation with French carmaker Renault, is
>> uncanny in the way it maintains optimal engine rpm within the most
>> fuel-efficient torque range. It senses, for example, when the Versa is
>> proceeding downhill and glides effortlessly into a lower gear range to
>> slow the car with engine braking. [What if you don't want engine
>> braking? It is wasting kinetic energy = fuel.
>
>not correct. when engine braking, fuel delivery is completely stopped.
But kinetic energy is being lost. Doesn't matter if the car has to be
brought to a stop anyway, but if the driving situation requires little
or no compression braking and the computer orders a lot, the car will
slow unnecessarily and fuel will be consumed bringing it back up to
speed.
I use compression braking a lot. Sometimes I use a little, sometimes
I use a lot. Sometimes I coast with the clutch disengaged for maximum
distance. A transmission that always applies medium compression
braking is not as going to achieve the same thing.
>> What it needs in a
>> powerful computer with optical sensors to look ahead, evaluate the
>> situation and decide whether engine braking is advantageous
>
>why? i don't want my car making /that/ kind of decision. seriously,
But you are satisfied with it making the decision mindlessly. I agree
I do not want the car making that decision. I want to make it myself
and shift the transmission accordingly. My brain is the powerful
computer and my eyes are the optical sensors.
>auto engine braking only happens when you're foot braking - just like on
>a stick.
Not true. I use compression braking all the time with my foot off the
brake. Descending grades would be a prime example except that I live
in Chicago and there are no hills. Instead, I am the only guy in
crawling rush hour traffic not flashing his brake lights every 20
feet. It is way more fun than an AT if you play the game.
>you can't criticize what you've not used dude.
I am only pointing out that this feature has a down side. It might
not bother 95% of drivers, but it would bother me.
>
>>.]
>> Conversely, under pedal-to-the-floor acceleration, the CVT instantly
>> launches the engine to its max-torque rpm, then keeps it there
>> unchanged until a desired highway speed is reached.
>>
>> This goes against every traditional sensation of driving, wherein gear
>> changes trigger a momentary drop in rpm as the higher gear ratio is
>> engaged. There's a lot of mechanical inefficiency in that traditional
>> gear-change syncopation; and Versa's CVT eliminates it. When first
>> experiencing the CVT's behavior, it feels wrong, sounds noisy. In
>> truth, however, it's mostly the lack of noticeable gear changes that's
>> merely thwarting a driver's subconscious expectation of rising-falling
>> rpms as gears change.
>> --end quote--
>>
>> http://www.carlist.com/newcars/2007/ncr1116.html
>>
>>
>>>>>> And yet, there is hardly a proliferation of CVTs on the market. Most
>>>>>> of them seem to be on hybrids in fact.
>>>>> that's consumer and mechanic inertia - nothing to do with benefits or
>>>>> reliability. trust me on that one - i've driven the daf for an extended
>>>>> period and it's a great system.
>>>> Maybe. I would gladly trade the AT in my Ody for one if it was proven
>>>> reliable. Not all are. The on in the Saturn Vue was a disaster, but
>>>> I guess you have to expect that from GM. The Japanese units don't
>>>> seem to have any problems.
>>> i've never heard of problems with the civic hx.
>>
>> Neither have I, but then there aren't a lot out there.
>
>/all/ the 96-2000 hx autos are cvt.
Yes, but how many is that? If they had sold that many, it would still
be on the market. Don't get me wrong, I don't think they are any less
reliable than a conventional Civic AT, but I don't think there are
enough out there to really know for sure. They certainly aren't
terrible like the GM CVT.
01-12-2007 | 12:50 AM
#95
Guest
Posts: n/a
Re: Transmission Activity
On Wed, 10 Jan 2007 20:43:45 -0800, jim beam
<spamvortex@bad.example.net> wrote:
>Gordon McGrew wrote:
>> On Mon, 08 Jan 2007 21:25:13 -0800, jim beam
>> <spamvortex@bad.example.net> wrote:
>>
>>> Gordon McGrew wrote:
>>>> On Sun, 07 Jan 2007 15:20:11 -0800, jim beam
>>>> <spamvortex@bad.example.net> wrote:
>>>>
>>>>>>>>>> The problem with most (virtually all) ATs is that they are biased
>>>>>>>>>> toward automatic operation and discourage manual operation.
>>>>>>>>> how? my auto has the shift in exactly the same place as where the stick
>>>>>>>>> would be. i see no difference. the transmission even has a no-lock
>>>>>>>>> gate between 3rd & 4th [commonest manual override] especially so you
>>>>>>>>> /can/ flip up and down at will.
>>>>>>>> If you put it in 4, will it ever downshift into 3 by itself?
>>>>>>> yes, absolutely. it does it on "kickdown" acceleration /and/ it does it
>>>>>>> on braking. not gentle braking, but harder braking.
>>>>>> It is not a bad thing, I just don't care for it. If I want to
>>>>>> downshift, I can do that. If I don't want to, I don't like the car
>>>>>> doing it on its own.
>>>>> why not? it's just like you'd have on a stick.
>>>> Not sure I understand. My GS-R never downshifts on its own.
>>> if it doesn't, then there's something wrong. how old is it?
>>
>> It is a '94 with a 5-speed manual transmission. What kind of MT cars
>> have you driven that shift themselves???
>
>i misunderstood you.
>
>originally, you said "If I want to downshift, I can do that." well, you
>can on an auto. on my car, the shifter is in the same place as a stick
>would be too. and the auto replicates engine braking when you need it -
>just like you'd do yourself. really, it's a good system.
>
>>
>>
>>>>>>>> When you
>>>>>>>> shift into 3 does it effectively double clutch?
>>>>>>> pointless exercise on an automatic. but even then, on the modern autos,
>>>>>>> in conjunction with electronic throttle, yes, the engine revs /are/
>>>>>>> meshed to the gear on shift.
>>>>>> That is what I mean. I figured they had fixed that aspect which is
>>>>>> the worst part of the older ATs.
>>>>>>
>>>>>>>>>> Also, I
>>>>>>>>>> don't particularly care for the slippage of the torque converter.
>>>>>>>>> eh? what "slippage" is that? how does its mechanical function differ
>>>>>>>> >from a clutch [other than it has a much better efficiency range and is
>>>>>>>>> much smoother of course]?
>>>>>>>> Well, as you point out, I don't have any experience with modern high
>>>>>>>> end luxury cars, but I note that at least more modest cars generally
>>>>>>>> have a significantly greater 0-60 speed and a lower mpg rating. Since
>>>>>>>> they now mostly have five gears, I would assume that means they are
>>>>>>>> slipping.
>>>>>>> there's no slipping unless the lock-up clutch is released. see below.
>>>>>>>
>>>>>>>> Actually, the slipping is partly by design, the so-called
>>>>>>>> torque multiplier effect.
>>>>>>> yes, that's what a torque converter does.
>>>>>>>
>>>>>>>> Basically, if you are cruising along and
>>>>>>>> you give it a little gas, but not enough to force a downshift, you
>>>>>>>> will see the rpms jump up immediately.
>>>>>>> that's because the lockup clutch is released to allow more torque. more
>>>>>>> flexibility than a stick where you'd have to shift.
>>>>>> But that is the slippage. The engine speeds up races up ahead of any
>>>>>> change in vehicle speed.
>>>>> but i don't understand the problem - what's wrong with it? engines are
>>>>> not perfect across all rev ranges - why not let a computer manage the
>>>>> efficiency curves - for that's what's happening.
>>>> It is just a personal preference. I like the engine to be positively
>>>> coupled to the wheels.
>>> that's what the lockup clutch in the torque converter is for.
>>
>> But it isn't engaged all the time. When it disengages, that is when
>> it "slips" and I do not find that satisfying as a driver.
>
>you'd hate cvt. as i said before, there's zero relation between engine
>speed and vehicle speed - if you drive on engine revs, and it sounds
>like you do, you'll be suffering total loss of feedback.
>
>> Like I said
>> a the outside, it is a preference for MT. I like to drive cars and
>> the MT is more enjoyable than the ATs I have driven. I don't like it
>> shifting when I don't want it to and I don't like the slippy feel of
>> the torque converter. The fact that the MT is usually faster and more
>> fuel efficient is a bonus.
>
>check the modern civics in that department.
The AT Civic gets slightly better highway mileage than the MT - I am
guessing it may have a higher final ratio. The Accord 4 and V6 and
the Fit all get better mileage with the MT. I don't have any test
results, but I bet the MTs are universally faster (see below.)
>>>>>> It is like a slipping clutch. As for more
>>>>>> torque (horsepower really) a lot of that is eaten up by the
>>>>>> inefficiency of the torque converter.
>>>>> how is a slipping clutch more efficient? [it's not.]
>>>> No, I understand that (unlike a slipping clutch) there is a benefit to
>>>> the slip designed into the AT. I just don't like the feel of it and
>>>> the benefit is more than eaten up by the inefficiencies that come with
>>>> it.
>>> you'd hate cvt. there's no "relationship" between revs and engine speed
>>> at all.
>>
>> I think you are probably right. That is why I mentioned the fact that
>> the CVT isn't very popular in the US (if anywhere) and I think it is
>> because lots of people hate it. Why else would Honda sell a 7-speed
>> CVT?
>
>because they rely on dealer feedback, and dealers are morons? cvt was
>pretty popular in europe iirc. volvo sold them as well as daf, and they
>did quite well.
Why is that in the past tense? We agree they are more efficient than
conventional ATs and if they were popular, why didn't they drive
conventional ATs off the market? Reliability could have been an issue
but shouldn't be now (as long as you stay away form GM.)
>>
>> OTOH, it probably appeals to - or at least doesn't repulse - the
>> hybrid buyer because it befits the unconventional nature of the car. I
>> realize there are technical benefits to the combination of hybrid and
>> CVT, but I am saying that the unconventional nature of the CVT is less
>> of a negative when you are already committed to buying an
>> unconventional vehicle. If you are attracted to the hybrid because it
>> is unconventional, the CVT is a plus.
>
>nah, it's a pure engineering logic decision. cvt allows extremely good
>engine efficiency. if you don't want that, you don't want a hybrid.
Exactly right. The converse of that statement is that, if you want
increased efficiency, you will tolerate or even embrace the CVT. And
if you like the hybrid because it is odd or technologically advanced,
then you will love the CVT.
>>>>>> On cars where you can get a MT
>>>>>> or AT with the same engine, the MT is almost always faster and gets
>>>>>> better mileage.
>>>>> not so with the modern autos. and that's one of the big things about
>>>>> honda autos - it's basically a standard transmission with clutch packs
>>>>> instead of synchros. inherently more efficient than planetary gears.
>>>> Looking at the differences between the ATs in the econo cars tested by
>>>> CR, Honda looks about as good as the other ATs (except for the CVT.)
>>> you're looking at fuel economy, right?
>>
>> Fuel economy was significantly better for the MTs but the biggest
>> difference was acceleration. The MTs blew the doors off the ATs. In
>> terms of 0 - 60 time differences, the Yaris AT was the best - "only"
>> 2.1 seconds slower than the MT version. Even the slowest MT car, the
>> Kia Rio was faster than the Versa CVT. The fastest AT car, the Yaris,
>> was 1.4 seconds slower than the Versa CVT.
>
>dude, compare like with like - not different car to different car if
>you're trying to compare trnasmissions, i.e. yaris with cvt, yaris with
>stick, etc. yaris stick to versa cvt doesn't work.
It doesn't matter whether you compare like to like or unlike to like.
All of the MTs are faster than all of the ATs and the CVT. Let me
tabulate it for you:
0-60 45-65 1/4 mi
Fit AT 12.4 8.4 19.0
Fit MT 9.9 6.5 17.4
Versa CVT 10.1 6.4 17.8
Versa MT 9.5 5.9 17.2
Rio AT 12.8 8.1 19.3
Rio MT 10.0 7.1 17.5
Accent AT 12.5 7.7 19.1
Accent MT 9.5 6.5 17.2
Yaris AT 11.4 6.9 18.6
Yaris MT 9.3 6.0 17.3
As I said, "The MTs blew the doors off the ATs."
>
>>
>>>>>>>> The ultimate "torque multiplier" is a CVT.
>>>>>>> that's different - it's not a torque multiplier.
>>>>>> Neither is the conventional AT, it just has a clever design to let the
>>>>>> engine speed up ahead of the vehicle speed without shifting. It is
>>>>>> basically like a limited range CVT.
>>>>> no dude, they're totally different. "torque multiplier" is something a
>>>>> torque converter can do - hence its name. everything else is ratio
>>>>> control, be it continuously variable or discrete.
>>>> OK, explain it to me. My understanding is that it is just a trick to
>>>> get the engine running at a slightly higher rpm to produce more power.
>>>> Kind of like a mini downshift. All car transmissions are torque
>>>> multipliers.
>>> ok, yes, but we're talking about different things. torque converters
>>> can increase torque output from a little to a lot in a very limited rev
>>> range. ratio change is something different and that's what the gears
>>> are for.
>>
>> You understand that the ATs torque output at a certain rpm (i.e. power
>> transmitted) is higher when the torque multiplication is active. There
>> are only two way this can happen. The first is to increase the
>> efficiency of the transmission. I think we can dismiss that. The
>> other way is to increase the power input.
>
>no, it depends on input/output speed differential. within certain rev
>ranges, torque transmission is very high, even with a rev differential.
> if it gets outside of that band, it drops right off.
http://en.wikipedia.org/wiki/Torque_...Multiplication
--quotes-- [my comments in brackets]
Unlike a fluid coupling, however, a torque converter is able to
multiply torque when there is a substantial difference between input
and output rotational speed, thus providing the equivalent of a
reduction gear. [IOW, a mini-downshift, a slightly lower gear that
allows the engine to run faster and produce more power.]
The principal difference is that whereas a fluid coupling is a two
element drive that is incapable of multiplying torque [IOW, it has a
1:1 ratio of input to output] , a torque converter has at least one
extra element - the stator - which alters the drive's characteristics
during periods of high slippage, producing an increase in output
torque. [IOW, it allows the engine to run faster and produce more
power, just like a lower gear.]
The Buick Dynaflow automatic transmission was a non-shifting design
and, under normal conditions, relied solely upon the converter to
multiply torque. [IOW, there was no gear transmission, all ratio
change was due to slippage of the TC - an early CVT!] The Dynaflow
used a five element converter to produce the wide range of torque
multiplication [i.e. wide range of drive ratios] needed to propel a
heavy vehicle.
* Acceleration. The load is accelerating but there still is a
relatively large difference between pump and turbine speed. [i.e. low
gear] ...The amount of multiplication will depend upon the actual
difference between pump and turbine speed, [i.e. the effective drive
ratio] as well as various other design factors. [efficiency]
* Coupling. The turbine has reached approximately 90 percent of
the speed of the pump. Torque multiplication has ceased [i.e. gear
ratio is slightly less than 1:1 but the slight power increase from
higher engine rpm is lost to inefficiency] and the torque converter is
behaving in a manner similar to a fluid coupling. In modern automotive
applications, it is usually at this stage of operation where the
lock-up clutch is applied, a procedure that tends to improve fuel
efficiency.
--end quotes--
When they say "torque multiplication" what they really mean is a drive
ratio less than 1:1. IOW, every transmission is a torque multiplier,
at least in the lower gears.
>
>> The only way to do that is
>> to increase the throttle opening or increase the rpm. The throttle
>> opening is determined by your foot (and it wouldn't be much of a trick
>> for the torque multiplier to be just an extra jerk on the throttle and
>> it wouldn't do much good if the throttle were already wide open.)
>> However, rpm is largely controlled by the transmission. The
>> transmission allows the engine to run a little faster and therefore
>> produce more power which is transmitted to the wheels. This is what I
>> meant by a mini downshift.
>
>that's the lockup clutch releasing.
Right, there is no torque multiplication in the TC unless it is
slipping.
>
>>
>>>> They take high rpm/low torque and turn it into low rpm
>>>> high torque. If it were perfectly efficient, the power output would
>>>> be equal to input but of course it is always less. No way to get more
>>>> power out unless you put more power in, i.e. run the engine at higher
>>>> rpm.
>>> see above.
>>>
>>>>>>> if is however a great
>>>>>>> way of achieving absolute optimum gear for all conditions.
>>>>>> I agree that it has a big theoretical advantage, especially compared
>>>>>> to a conventional AT.
>>>>> compared to /any/ transmission. there are mechanical efficiency issues
>>>>> with the friction interface, but that is more than outweighed by ratio
>>>>> flexibility and ability to keep the engine at its most efficient.
>>>> The why doesn't the Versa with a CVT get better mileage or accelerate
>>>> faster than the Versa with an MT? Unfortunately, there are few cars
>>>> which allow you to directly compare CVT vs. MT.
>>> civic hx was significantly more fuel efficient than the stick.
>>
>> I gather that was the CVT-equipped model. They don't sell it anymore.
>> I guess people hated it more than high fuel costs.
>
>my money's on dealer prejudice, not consumer. by the same token, the
>hatchback has been all but dropped in the u.s. afaikt, that's more to
>do with vehicles with the same utility selling for $30k rather than $15k
>for a hatch, not consumer demand. try buying a used hatchback civic
>here in the bay area - good luck! people just keep them - they never
>sell.
I personally like hatchbacks and I know they have a following. I too
am surprised and disappointed that they have all but disappeared. I
don't know I am ready to sign on to the conspiracy theory though. If
there were a strong market, Someone like Mazda or Nissan would jump to
serve it to increase their sales. apparently there isn't enough
demand to justify the high expense of two body styles and the sedan is
more popular.
I suppose I could blame the shortage of MTs on greedy dealers and
manufacturers who want to force me to buy a more expensive AT.
However, I am more inclined to blame Starbucks.
>>>>>>>> A lot of people don't like
>>>>>>>> them at all, but others say they get used to it. (The perception
>>>>>>>> problem is so bad that some manufacturers program virtual gears into
>>>>>>>> them thereby defeating the chief advantage of the CVT.)
>>>>>>> absolutely! i drove a "real" cvt one when i was in europe years ago,
>>>>>>> and yes it is /real/ weird at first. but it's amazing how much you can
>>>>>>> get out of a small 2-cylinder engine when it's got perfect gearing.
>>>>>>> quite fun! this particular model had 2 independent drives too, so not
>>>>>>> only did you have optimum gearing, you had limited slip diff benefits in
>>>>>>> snow & ice too.
>>>>>>> http://www.ritzsite.demon.nl/DAF/DAF_cars_p2.htm
>>>>>> That was the original CVT. Do you remember who offered the first CVT
>>>>>> in the US. (I don't think they ever sold the Daffodil here.)
>>>>> subaru?
>>>> That is what I recall. The car was called the Justy.
>>>>
>>>>>>>> I only rode
>>>>>>>> in one CVT car, a Nissan luxury sedan in Japan and it wasn't bad in
>>>>>>>> that application. He drove it fairly aggressively too - we hit almost
>>>>>>>> 180 kph on the expressway. I would like to try one of these. I don't
>>>>>>>> know if I would like it or not.
>>>>>>> if you're not used to traditional automatics, the transition is easy.
>>>>>>> if you're used to traditional autos, its weird for a few minutes because
>>>>>>> it doesn't "shift", but beyond that, they're actually very impressive.
>>>>>> Again though, I am not sure they are any faster or more efficient than
>>>>>> a good MT.
>>>>> well, the daf was only 650cc iirc, and 0-30, that wasn't much to touch it.
>>>> I think the Honda 600 would have blown its petals off. ;-)
>>>>
>>>>>> Consumer Reports tested the Versa with MT and with CVT.
>>>>>> The MT version was 0.6 seconds faster to 60 and got one more mpg. (And
>>>>>> CR panned that MT.) They also tested MT and (conventional) AT
>>>>>> versions of Fit, Rio, Accent and Yaris. In each case the MT was 2 - 3
>>>>>> seconds faster and got 2 more mpg, so the CVT was clearly better than
>>>>>> an AT but not as good as even a mediocre MT, at last on raw numbers.
>>>>> that depends on the management system. the modern cvt's "simulate" gear
>>>>> shifts which is the dumbest damned thing since it's not utilizing the
>>>>> inherent benefit of the system! on that basis, i'm not surprised.
>>>> Does the Versa do that? CR didn't mention it.
>>> don't know. given "consumer demand", i expect so.
>>
>> Like I said, they hate it just like you think I would. (Actually I
>> would love to try one, I do think it is a neat idea and it would be
>> fun for a while at least. Only after the novelty wore off could I
>> tell you if I like it or hate it. I actually suspect that I would
>> like it more than a conventional AT.)
>>
>> Here is an interesting review I found. (It indicates that the Versa
>> CVT does not have "gears," so the fact that it was slower and less
>> fuel efficient than the "clunky" MT is significant.) I made one
>> editorial comment in brackets.
>>
>> --quote--
>> But the CVT is the one that shines. Its proprietary design, benefiting
>> from Nissan's global cooperation with French carmaker Renault, is
>> uncanny in the way it maintains optimal engine rpm within the most
>> fuel-efficient torque range. It senses, for example, when the Versa is
>> proceeding downhill and glides effortlessly into a lower gear range to
>> slow the car with engine braking. [What if you don't want engine
>> braking? It is wasting kinetic energy = fuel.
>
>not correct. when engine braking, fuel delivery is completely stopped.
But kinetic energy is being lost. Doesn't matter if the car has to be
brought to a stop anyway, but if the driving situation requires little
or no compression braking and the computer orders a lot, the car will
slow unnecessarily and fuel will be consumed bringing it back up to
speed.
I use compression braking a lot. Sometimes I use a little, sometimes
I use a lot. Sometimes I coast with the clutch disengaged for maximum
distance. A transmission that always applies medium compression
braking is not as going to achieve the same thing.
>> What it needs in a
>> powerful computer with optical sensors to look ahead, evaluate the
>> situation and decide whether engine braking is advantageous
>
>why? i don't want my car making /that/ kind of decision. seriously,
But you are satisfied with it making the decision mindlessly. I agree
I do not want the car making that decision. I want to make it myself
and shift the transmission accordingly. My brain is the powerful
computer and my eyes are the optical sensors.
>auto engine braking only happens when you're foot braking - just like on
>a stick.
Not true. I use compression braking all the time with my foot off the
brake. Descending grades would be a prime example except that I live
in Chicago and there are no hills. Instead, I am the only guy in
crawling rush hour traffic not flashing his brake lights every 20
feet. It is way more fun than an AT if you play the game.
>you can't criticize what you've not used dude.
I am only pointing out that this feature has a down side. It might
not bother 95% of drivers, but it would bother me.
>
>>.]
>> Conversely, under pedal-to-the-floor acceleration, the CVT instantly
>> launches the engine to its max-torque rpm, then keeps it there
>> unchanged until a desired highway speed is reached.
>>
>> This goes against every traditional sensation of driving, wherein gear
>> changes trigger a momentary drop in rpm as the higher gear ratio is
>> engaged. There's a lot of mechanical inefficiency in that traditional
>> gear-change syncopation; and Versa's CVT eliminates it. When first
>> experiencing the CVT's behavior, it feels wrong, sounds noisy. In
>> truth, however, it's mostly the lack of noticeable gear changes that's
>> merely thwarting a driver's subconscious expectation of rising-falling
>> rpms as gears change.
>> --end quote--
>>
>> http://www.carlist.com/newcars/2007/ncr1116.html
>>
>>
>>>>>> And yet, there is hardly a proliferation of CVTs on the market. Most
>>>>>> of them seem to be on hybrids in fact.
>>>>> that's consumer and mechanic inertia - nothing to do with benefits or
>>>>> reliability. trust me on that one - i've driven the daf for an extended
>>>>> period and it's a great system.
>>>> Maybe. I would gladly trade the AT in my Ody for one if it was proven
>>>> reliable. Not all are. The on in the Saturn Vue was a disaster, but
>>>> I guess you have to expect that from GM. The Japanese units don't
>>>> seem to have any problems.
>>> i've never heard of problems with the civic hx.
>>
>> Neither have I, but then there aren't a lot out there.
>
>/all/ the 96-2000 hx autos are cvt.
Yes, but how many is that? If they had sold that many, it would still
be on the market. Don't get me wrong, I don't think they are any less
reliable than a conventional Civic AT, but I don't think there are
enough out there to really know for sure. They certainly aren't
terrible like the GM CVT.
<spamvortex@bad.example.net> wrote:
>Gordon McGrew wrote:
>> On Mon, 08 Jan 2007 21:25:13 -0800, jim beam
>> <spamvortex@bad.example.net> wrote:
>>
>>> Gordon McGrew wrote:
>>>> On Sun, 07 Jan 2007 15:20:11 -0800, jim beam
>>>> <spamvortex@bad.example.net> wrote:
>>>>
>>>>>>>>>> The problem with most (virtually all) ATs is that they are biased
>>>>>>>>>> toward automatic operation and discourage manual operation.
>>>>>>>>> how? my auto has the shift in exactly the same place as where the stick
>>>>>>>>> would be. i see no difference. the transmission even has a no-lock
>>>>>>>>> gate between 3rd & 4th [commonest manual override] especially so you
>>>>>>>>> /can/ flip up and down at will.
>>>>>>>> If you put it in 4, will it ever downshift into 3 by itself?
>>>>>>> yes, absolutely. it does it on "kickdown" acceleration /and/ it does it
>>>>>>> on braking. not gentle braking, but harder braking.
>>>>>> It is not a bad thing, I just don't care for it. If I want to
>>>>>> downshift, I can do that. If I don't want to, I don't like the car
>>>>>> doing it on its own.
>>>>> why not? it's just like you'd have on a stick.
>>>> Not sure I understand. My GS-R never downshifts on its own.
>>> if it doesn't, then there's something wrong. how old is it?
>>
>> It is a '94 with a 5-speed manual transmission. What kind of MT cars
>> have you driven that shift themselves???
>
>i misunderstood you.
>
>originally, you said "If I want to downshift, I can do that." well, you
>can on an auto. on my car, the shifter is in the same place as a stick
>would be too. and the auto replicates engine braking when you need it -
>just like you'd do yourself. really, it's a good system.
>
>>
>>
>>>>>>>> When you
>>>>>>>> shift into 3 does it effectively double clutch?
>>>>>>> pointless exercise on an automatic. but even then, on the modern autos,
>>>>>>> in conjunction with electronic throttle, yes, the engine revs /are/
>>>>>>> meshed to the gear on shift.
>>>>>> That is what I mean. I figured they had fixed that aspect which is
>>>>>> the worst part of the older ATs.
>>>>>>
>>>>>>>>>> Also, I
>>>>>>>>>> don't particularly care for the slippage of the torque converter.
>>>>>>>>> eh? what "slippage" is that? how does its mechanical function differ
>>>>>>>> >from a clutch [other than it has a much better efficiency range and is
>>>>>>>>> much smoother of course]?
>>>>>>>> Well, as you point out, I don't have any experience with modern high
>>>>>>>> end luxury cars, but I note that at least more modest cars generally
>>>>>>>> have a significantly greater 0-60 speed and a lower mpg rating. Since
>>>>>>>> they now mostly have five gears, I would assume that means they are
>>>>>>>> slipping.
>>>>>>> there's no slipping unless the lock-up clutch is released. see below.
>>>>>>>
>>>>>>>> Actually, the slipping is partly by design, the so-called
>>>>>>>> torque multiplier effect.
>>>>>>> yes, that's what a torque converter does.
>>>>>>>
>>>>>>>> Basically, if you are cruising along and
>>>>>>>> you give it a little gas, but not enough to force a downshift, you
>>>>>>>> will see the rpms jump up immediately.
>>>>>>> that's because the lockup clutch is released to allow more torque. more
>>>>>>> flexibility than a stick where you'd have to shift.
>>>>>> But that is the slippage. The engine speeds up races up ahead of any
>>>>>> change in vehicle speed.
>>>>> but i don't understand the problem - what's wrong with it? engines are
>>>>> not perfect across all rev ranges - why not let a computer manage the
>>>>> efficiency curves - for that's what's happening.
>>>> It is just a personal preference. I like the engine to be positively
>>>> coupled to the wheels.
>>> that's what the lockup clutch in the torque converter is for.
>>
>> But it isn't engaged all the time. When it disengages, that is when
>> it "slips" and I do not find that satisfying as a driver.
>
>you'd hate cvt. as i said before, there's zero relation between engine
>speed and vehicle speed - if you drive on engine revs, and it sounds
>like you do, you'll be suffering total loss of feedback.
>
>> Like I said
>> a the outside, it is a preference for MT. I like to drive cars and
>> the MT is more enjoyable than the ATs I have driven. I don't like it
>> shifting when I don't want it to and I don't like the slippy feel of
>> the torque converter. The fact that the MT is usually faster and more
>> fuel efficient is a bonus.
>
>check the modern civics in that department.
The AT Civic gets slightly better highway mileage than the MT - I am
guessing it may have a higher final ratio. The Accord 4 and V6 and
the Fit all get better mileage with the MT. I don't have any test
results, but I bet the MTs are universally faster (see below.)
>>>>>> It is like a slipping clutch. As for more
>>>>>> torque (horsepower really) a lot of that is eaten up by the
>>>>>> inefficiency of the torque converter.
>>>>> how is a slipping clutch more efficient? [it's not.]
>>>> No, I understand that (unlike a slipping clutch) there is a benefit to
>>>> the slip designed into the AT. I just don't like the feel of it and
>>>> the benefit is more than eaten up by the inefficiencies that come with
>>>> it.
>>> you'd hate cvt. there's no "relationship" between revs and engine speed
>>> at all.
>>
>> I think you are probably right. That is why I mentioned the fact that
>> the CVT isn't very popular in the US (if anywhere) and I think it is
>> because lots of people hate it. Why else would Honda sell a 7-speed
>> CVT?
>
>because they rely on dealer feedback, and dealers are morons? cvt was
>pretty popular in europe iirc. volvo sold them as well as daf, and they
>did quite well.
Why is that in the past tense? We agree they are more efficient than
conventional ATs and if they were popular, why didn't they drive
conventional ATs off the market? Reliability could have been an issue
but shouldn't be now (as long as you stay away form GM.)
>>
>> OTOH, it probably appeals to - or at least doesn't repulse - the
>> hybrid buyer because it befits the unconventional nature of the car. I
>> realize there are technical benefits to the combination of hybrid and
>> CVT, but I am saying that the unconventional nature of the CVT is less
>> of a negative when you are already committed to buying an
>> unconventional vehicle. If you are attracted to the hybrid because it
>> is unconventional, the CVT is a plus.
>
>nah, it's a pure engineering logic decision. cvt allows extremely good
>engine efficiency. if you don't want that, you don't want a hybrid.
Exactly right. The converse of that statement is that, if you want
increased efficiency, you will tolerate or even embrace the CVT. And
if you like the hybrid because it is odd or technologically advanced,
then you will love the CVT.
>>>>>> On cars where you can get a MT
>>>>>> or AT with the same engine, the MT is almost always faster and gets
>>>>>> better mileage.
>>>>> not so with the modern autos. and that's one of the big things about
>>>>> honda autos - it's basically a standard transmission with clutch packs
>>>>> instead of synchros. inherently more efficient than planetary gears.
>>>> Looking at the differences between the ATs in the econo cars tested by
>>>> CR, Honda looks about as good as the other ATs (except for the CVT.)
>>> you're looking at fuel economy, right?
>>
>> Fuel economy was significantly better for the MTs but the biggest
>> difference was acceleration. The MTs blew the doors off the ATs. In
>> terms of 0 - 60 time differences, the Yaris AT was the best - "only"
>> 2.1 seconds slower than the MT version. Even the slowest MT car, the
>> Kia Rio was faster than the Versa CVT. The fastest AT car, the Yaris,
>> was 1.4 seconds slower than the Versa CVT.
>
>dude, compare like with like - not different car to different car if
>you're trying to compare trnasmissions, i.e. yaris with cvt, yaris with
>stick, etc. yaris stick to versa cvt doesn't work.
It doesn't matter whether you compare like to like or unlike to like.
All of the MTs are faster than all of the ATs and the CVT. Let me
tabulate it for you:
0-60 45-65 1/4 mi
Fit AT 12.4 8.4 19.0
Fit MT 9.9 6.5 17.4
Versa CVT 10.1 6.4 17.8
Versa MT 9.5 5.9 17.2
Rio AT 12.8 8.1 19.3
Rio MT 10.0 7.1 17.5
Accent AT 12.5 7.7 19.1
Accent MT 9.5 6.5 17.2
Yaris AT 11.4 6.9 18.6
Yaris MT 9.3 6.0 17.3
As I said, "The MTs blew the doors off the ATs."
>
>>
>>>>>>>> The ultimate "torque multiplier" is a CVT.
>>>>>>> that's different - it's not a torque multiplier.
>>>>>> Neither is the conventional AT, it just has a clever design to let the
>>>>>> engine speed up ahead of the vehicle speed without shifting. It is
>>>>>> basically like a limited range CVT.
>>>>> no dude, they're totally different. "torque multiplier" is something a
>>>>> torque converter can do - hence its name. everything else is ratio
>>>>> control, be it continuously variable or discrete.
>>>> OK, explain it to me. My understanding is that it is just a trick to
>>>> get the engine running at a slightly higher rpm to produce more power.
>>>> Kind of like a mini downshift. All car transmissions are torque
>>>> multipliers.
>>> ok, yes, but we're talking about different things. torque converters
>>> can increase torque output from a little to a lot in a very limited rev
>>> range. ratio change is something different and that's what the gears
>>> are for.
>>
>> You understand that the ATs torque output at a certain rpm (i.e. power
>> transmitted) is higher when the torque multiplication is active. There
>> are only two way this can happen. The first is to increase the
>> efficiency of the transmission. I think we can dismiss that. The
>> other way is to increase the power input.
>
>no, it depends on input/output speed differential. within certain rev
>ranges, torque transmission is very high, even with a rev differential.
> if it gets outside of that band, it drops right off.
http://en.wikipedia.org/wiki/Torque_...Multiplication
--quotes-- [my comments in brackets]
Unlike a fluid coupling, however, a torque converter is able to
multiply torque when there is a substantial difference between input
and output rotational speed, thus providing the equivalent of a
reduction gear. [IOW, a mini-downshift, a slightly lower gear that
allows the engine to run faster and produce more power.]
The principal difference is that whereas a fluid coupling is a two
element drive that is incapable of multiplying torque [IOW, it has a
1:1 ratio of input to output] , a torque converter has at least one
extra element - the stator - which alters the drive's characteristics
during periods of high slippage, producing an increase in output
torque. [IOW, it allows the engine to run faster and produce more
power, just like a lower gear.]
The Buick Dynaflow automatic transmission was a non-shifting design
and, under normal conditions, relied solely upon the converter to
multiply torque. [IOW, there was no gear transmission, all ratio
change was due to slippage of the TC - an early CVT!] The Dynaflow
used a five element converter to produce the wide range of torque
multiplication [i.e. wide range of drive ratios] needed to propel a
heavy vehicle.
* Acceleration. The load is accelerating but there still is a
relatively large difference between pump and turbine speed. [i.e. low
gear] ...The amount of multiplication will depend upon the actual
difference between pump and turbine speed, [i.e. the effective drive
ratio] as well as various other design factors. [efficiency]
* Coupling. The turbine has reached approximately 90 percent of
the speed of the pump. Torque multiplication has ceased [i.e. gear
ratio is slightly less than 1:1 but the slight power increase from
higher engine rpm is lost to inefficiency] and the torque converter is
behaving in a manner similar to a fluid coupling. In modern automotive
applications, it is usually at this stage of operation where the
lock-up clutch is applied, a procedure that tends to improve fuel
efficiency.
--end quotes--
When they say "torque multiplication" what they really mean is a drive
ratio less than 1:1. IOW, every transmission is a torque multiplier,
at least in the lower gears.
>
>> The only way to do that is
>> to increase the throttle opening or increase the rpm. The throttle
>> opening is determined by your foot (and it wouldn't be much of a trick
>> for the torque multiplier to be just an extra jerk on the throttle and
>> it wouldn't do much good if the throttle were already wide open.)
>> However, rpm is largely controlled by the transmission. The
>> transmission allows the engine to run a little faster and therefore
>> produce more power which is transmitted to the wheels. This is what I
>> meant by a mini downshift.
>
>that's the lockup clutch releasing.
Right, there is no torque multiplication in the TC unless it is
slipping.
>
>>
>>>> They take high rpm/low torque and turn it into low rpm
>>>> high torque. If it were perfectly efficient, the power output would
>>>> be equal to input but of course it is always less. No way to get more
>>>> power out unless you put more power in, i.e. run the engine at higher
>>>> rpm.
>>> see above.
>>>
>>>>>>> if is however a great
>>>>>>> way of achieving absolute optimum gear for all conditions.
>>>>>> I agree that it has a big theoretical advantage, especially compared
>>>>>> to a conventional AT.
>>>>> compared to /any/ transmission. there are mechanical efficiency issues
>>>>> with the friction interface, but that is more than outweighed by ratio
>>>>> flexibility and ability to keep the engine at its most efficient.
>>>> The why doesn't the Versa with a CVT get better mileage or accelerate
>>>> faster than the Versa with an MT? Unfortunately, there are few cars
>>>> which allow you to directly compare CVT vs. MT.
>>> civic hx was significantly more fuel efficient than the stick.
>>
>> I gather that was the CVT-equipped model. They don't sell it anymore.
>> I guess people hated it more than high fuel costs.
>
>my money's on dealer prejudice, not consumer. by the same token, the
>hatchback has been all but dropped in the u.s. afaikt, that's more to
>do with vehicles with the same utility selling for $30k rather than $15k
>for a hatch, not consumer demand. try buying a used hatchback civic
>here in the bay area - good luck! people just keep them - they never
>sell.
I personally like hatchbacks and I know they have a following. I too
am surprised and disappointed that they have all but disappeared. I
don't know I am ready to sign on to the conspiracy theory though. If
there were a strong market, Someone like Mazda or Nissan would jump to
serve it to increase their sales. apparently there isn't enough
demand to justify the high expense of two body styles and the sedan is
more popular.
I suppose I could blame the shortage of MTs on greedy dealers and
manufacturers who want to force me to buy a more expensive AT.
However, I am more inclined to blame Starbucks.
>>>>>>>> A lot of people don't like
>>>>>>>> them at all, but others say they get used to it. (The perception
>>>>>>>> problem is so bad that some manufacturers program virtual gears into
>>>>>>>> them thereby defeating the chief advantage of the CVT.)
>>>>>>> absolutely! i drove a "real" cvt one when i was in europe years ago,
>>>>>>> and yes it is /real/ weird at first. but it's amazing how much you can
>>>>>>> get out of a small 2-cylinder engine when it's got perfect gearing.
>>>>>>> quite fun! this particular model had 2 independent drives too, so not
>>>>>>> only did you have optimum gearing, you had limited slip diff benefits in
>>>>>>> snow & ice too.
>>>>>>> http://www.ritzsite.demon.nl/DAF/DAF_cars_p2.htm
>>>>>> That was the original CVT. Do you remember who offered the first CVT
>>>>>> in the US. (I don't think they ever sold the Daffodil here.)
>>>>> subaru?
>>>> That is what I recall. The car was called the Justy.
>>>>
>>>>>>>> I only rode
>>>>>>>> in one CVT car, a Nissan luxury sedan in Japan and it wasn't bad in
>>>>>>>> that application. He drove it fairly aggressively too - we hit almost
>>>>>>>> 180 kph on the expressway. I would like to try one of these. I don't
>>>>>>>> know if I would like it or not.
>>>>>>> if you're not used to traditional automatics, the transition is easy.
>>>>>>> if you're used to traditional autos, its weird for a few minutes because
>>>>>>> it doesn't "shift", but beyond that, they're actually very impressive.
>>>>>> Again though, I am not sure they are any faster or more efficient than
>>>>>> a good MT.
>>>>> well, the daf was only 650cc iirc, and 0-30, that wasn't much to touch it.
>>>> I think the Honda 600 would have blown its petals off. ;-)
>>>>
>>>>>> Consumer Reports tested the Versa with MT and with CVT.
>>>>>> The MT version was 0.6 seconds faster to 60 and got one more mpg. (And
>>>>>> CR panned that MT.) They also tested MT and (conventional) AT
>>>>>> versions of Fit, Rio, Accent and Yaris. In each case the MT was 2 - 3
>>>>>> seconds faster and got 2 more mpg, so the CVT was clearly better than
>>>>>> an AT but not as good as even a mediocre MT, at last on raw numbers.
>>>>> that depends on the management system. the modern cvt's "simulate" gear
>>>>> shifts which is the dumbest damned thing since it's not utilizing the
>>>>> inherent benefit of the system! on that basis, i'm not surprised.
>>>> Does the Versa do that? CR didn't mention it.
>>> don't know. given "consumer demand", i expect so.
>>
>> Like I said, they hate it just like you think I would. (Actually I
>> would love to try one, I do think it is a neat idea and it would be
>> fun for a while at least. Only after the novelty wore off could I
>> tell you if I like it or hate it. I actually suspect that I would
>> like it more than a conventional AT.)
>>
>> Here is an interesting review I found. (It indicates that the Versa
>> CVT does not have "gears," so the fact that it was slower and less
>> fuel efficient than the "clunky" MT is significant.) I made one
>> editorial comment in brackets.
>>
>> --quote--
>> But the CVT is the one that shines. Its proprietary design, benefiting
>> from Nissan's global cooperation with French carmaker Renault, is
>> uncanny in the way it maintains optimal engine rpm within the most
>> fuel-efficient torque range. It senses, for example, when the Versa is
>> proceeding downhill and glides effortlessly into a lower gear range to
>> slow the car with engine braking. [What if you don't want engine
>> braking? It is wasting kinetic energy = fuel.
>
>not correct. when engine braking, fuel delivery is completely stopped.
But kinetic energy is being lost. Doesn't matter if the car has to be
brought to a stop anyway, but if the driving situation requires little
or no compression braking and the computer orders a lot, the car will
slow unnecessarily and fuel will be consumed bringing it back up to
speed.
I use compression braking a lot. Sometimes I use a little, sometimes
I use a lot. Sometimes I coast with the clutch disengaged for maximum
distance. A transmission that always applies medium compression
braking is not as going to achieve the same thing.
>> What it needs in a
>> powerful computer with optical sensors to look ahead, evaluate the
>> situation and decide whether engine braking is advantageous
>
>why? i don't want my car making /that/ kind of decision. seriously,
But you are satisfied with it making the decision mindlessly. I agree
I do not want the car making that decision. I want to make it myself
and shift the transmission accordingly. My brain is the powerful
computer and my eyes are the optical sensors.
>auto engine braking only happens when you're foot braking - just like on
>a stick.
Not true. I use compression braking all the time with my foot off the
brake. Descending grades would be a prime example except that I live
in Chicago and there are no hills. Instead, I am the only guy in
crawling rush hour traffic not flashing his brake lights every 20
feet. It is way more fun than an AT if you play the game.
>you can't criticize what you've not used dude.
I am only pointing out that this feature has a down side. It might
not bother 95% of drivers, but it would bother me.
>
>>.]
>> Conversely, under pedal-to-the-floor acceleration, the CVT instantly
>> launches the engine to its max-torque rpm, then keeps it there
>> unchanged until a desired highway speed is reached.
>>
>> This goes against every traditional sensation of driving, wherein gear
>> changes trigger a momentary drop in rpm as the higher gear ratio is
>> engaged. There's a lot of mechanical inefficiency in that traditional
>> gear-change syncopation; and Versa's CVT eliminates it. When first
>> experiencing the CVT's behavior, it feels wrong, sounds noisy. In
>> truth, however, it's mostly the lack of noticeable gear changes that's
>> merely thwarting a driver's subconscious expectation of rising-falling
>> rpms as gears change.
>> --end quote--
>>
>> http://www.carlist.com/newcars/2007/ncr1116.html
>>
>>
>>>>>> And yet, there is hardly a proliferation of CVTs on the market. Most
>>>>>> of them seem to be on hybrids in fact.
>>>>> that's consumer and mechanic inertia - nothing to do with benefits or
>>>>> reliability. trust me on that one - i've driven the daf for an extended
>>>>> period and it's a great system.
>>>> Maybe. I would gladly trade the AT in my Ody for one if it was proven
>>>> reliable. Not all are. The on in the Saturn Vue was a disaster, but
>>>> I guess you have to expect that from GM. The Japanese units don't
>>>> seem to have any problems.
>>> i've never heard of problems with the civic hx.
>>
>> Neither have I, but then there aren't a lot out there.
>
>/all/ the 96-2000 hx autos are cvt.
Yes, but how many is that? If they had sold that many, it would still
be on the market. Don't get me wrong, I don't think they are any less
reliable than a conventional Civic AT, but I don't think there are
enough out there to really know for sure. They certainly aren't
terrible like the GM CVT.
01-12-2007 | 12:50 AM
#96
Guest
Posts: n/a
Re: Transmission Activity
On Wed, 10 Jan 2007 20:43:45 -0800, jim beam
<spamvortex@bad.example.net> wrote:
>Gordon McGrew wrote:
>> On Mon, 08 Jan 2007 21:25:13 -0800, jim beam
>> <spamvortex@bad.example.net> wrote:
>>
>>> Gordon McGrew wrote:
>>>> On Sun, 07 Jan 2007 15:20:11 -0800, jim beam
>>>> <spamvortex@bad.example.net> wrote:
>>>>
>>>>>>>>>> The problem with most (virtually all) ATs is that they are biased
>>>>>>>>>> toward automatic operation and discourage manual operation.
>>>>>>>>> how? my auto has the shift in exactly the same place as where the stick
>>>>>>>>> would be. i see no difference. the transmission even has a no-lock
>>>>>>>>> gate between 3rd & 4th [commonest manual override] especially so you
>>>>>>>>> /can/ flip up and down at will.
>>>>>>>> If you put it in 4, will it ever downshift into 3 by itself?
>>>>>>> yes, absolutely. it does it on "kickdown" acceleration /and/ it does it
>>>>>>> on braking. not gentle braking, but harder braking.
>>>>>> It is not a bad thing, I just don't care for it. If I want to
>>>>>> downshift, I can do that. If I don't want to, I don't like the car
>>>>>> doing it on its own.
>>>>> why not? it's just like you'd have on a stick.
>>>> Not sure I understand. My GS-R never downshifts on its own.
>>> if it doesn't, then there's something wrong. how old is it?
>>
>> It is a '94 with a 5-speed manual transmission. What kind of MT cars
>> have you driven that shift themselves???
>
>i misunderstood you.
>
>originally, you said "If I want to downshift, I can do that." well, you
>can on an auto. on my car, the shifter is in the same place as a stick
>would be too. and the auto replicates engine braking when you need it -
>just like you'd do yourself. really, it's a good system.
>
>>
>>
>>>>>>>> When you
>>>>>>>> shift into 3 does it effectively double clutch?
>>>>>>> pointless exercise on an automatic. but even then, on the modern autos,
>>>>>>> in conjunction with electronic throttle, yes, the engine revs /are/
>>>>>>> meshed to the gear on shift.
>>>>>> That is what I mean. I figured they had fixed that aspect which is
>>>>>> the worst part of the older ATs.
>>>>>>
>>>>>>>>>> Also, I
>>>>>>>>>> don't particularly care for the slippage of the torque converter.
>>>>>>>>> eh? what "slippage" is that? how does its mechanical function differ
>>>>>>>> >from a clutch [other than it has a much better efficiency range and is
>>>>>>>>> much smoother of course]?
>>>>>>>> Well, as you point out, I don't have any experience with modern high
>>>>>>>> end luxury cars, but I note that at least more modest cars generally
>>>>>>>> have a significantly greater 0-60 speed and a lower mpg rating. Since
>>>>>>>> they now mostly have five gears, I would assume that means they are
>>>>>>>> slipping.
>>>>>>> there's no slipping unless the lock-up clutch is released. see below.
>>>>>>>
>>>>>>>> Actually, the slipping is partly by design, the so-called
>>>>>>>> torque multiplier effect.
>>>>>>> yes, that's what a torque converter does.
>>>>>>>
>>>>>>>> Basically, if you are cruising along and
>>>>>>>> you give it a little gas, but not enough to force a downshift, you
>>>>>>>> will see the rpms jump up immediately.
>>>>>>> that's because the lockup clutch is released to allow more torque. more
>>>>>>> flexibility than a stick where you'd have to shift.
>>>>>> But that is the slippage. The engine speeds up races up ahead of any
>>>>>> change in vehicle speed.
>>>>> but i don't understand the problem - what's wrong with it? engines are
>>>>> not perfect across all rev ranges - why not let a computer manage the
>>>>> efficiency curves - for that's what's happening.
>>>> It is just a personal preference. I like the engine to be positively
>>>> coupled to the wheels.
>>> that's what the lockup clutch in the torque converter is for.
>>
>> But it isn't engaged all the time. When it disengages, that is when
>> it "slips" and I do not find that satisfying as a driver.
>
>you'd hate cvt. as i said before, there's zero relation between engine
>speed and vehicle speed - if you drive on engine revs, and it sounds
>like you do, you'll be suffering total loss of feedback.
>
>> Like I said
>> a the outside, it is a preference for MT. I like to drive cars and
>> the MT is more enjoyable than the ATs I have driven. I don't like it
>> shifting when I don't want it to and I don't like the slippy feel of
>> the torque converter. The fact that the MT is usually faster and more
>> fuel efficient is a bonus.
>
>check the modern civics in that department.
The AT Civic gets slightly better highway mileage than the MT - I am
guessing it may have a higher final ratio. The Accord 4 and V6 and
the Fit all get better mileage with the MT. I don't have any test
results, but I bet the MTs are universally faster (see below.)
>>>>>> It is like a slipping clutch. As for more
>>>>>> torque (horsepower really) a lot of that is eaten up by the
>>>>>> inefficiency of the torque converter.
>>>>> how is a slipping clutch more efficient? [it's not.]
>>>> No, I understand that (unlike a slipping clutch) there is a benefit to
>>>> the slip designed into the AT. I just don't like the feel of it and
>>>> the benefit is more than eaten up by the inefficiencies that come with
>>>> it.
>>> you'd hate cvt. there's no "relationship" between revs and engine speed
>>> at all.
>>
>> I think you are probably right. That is why I mentioned the fact that
>> the CVT isn't very popular in the US (if anywhere) and I think it is
>> because lots of people hate it. Why else would Honda sell a 7-speed
>> CVT?
>
>because they rely on dealer feedback, and dealers are morons? cvt was
>pretty popular in europe iirc. volvo sold them as well as daf, and they
>did quite well.
Why is that in the past tense? We agree they are more efficient than
conventional ATs and if they were popular, why didn't they drive
conventional ATs off the market? Reliability could have been an issue
but shouldn't be now (as long as you stay away form GM.)
>>
>> OTOH, it probably appeals to - or at least doesn't repulse - the
>> hybrid buyer because it befits the unconventional nature of the car. I
>> realize there are technical benefits to the combination of hybrid and
>> CVT, but I am saying that the unconventional nature of the CVT is less
>> of a negative when you are already committed to buying an
>> unconventional vehicle. If you are attracted to the hybrid because it
>> is unconventional, the CVT is a plus.
>
>nah, it's a pure engineering logic decision. cvt allows extremely good
>engine efficiency. if you don't want that, you don't want a hybrid.
Exactly right. The converse of that statement is that, if you want
increased efficiency, you will tolerate or even embrace the CVT. And
if you like the hybrid because it is odd or technologically advanced,
then you will love the CVT.
>>>>>> On cars where you can get a MT
>>>>>> or AT with the same engine, the MT is almost always faster and gets
>>>>>> better mileage.
>>>>> not so with the modern autos. and that's one of the big things about
>>>>> honda autos - it's basically a standard transmission with clutch packs
>>>>> instead of synchros. inherently more efficient than planetary gears.
>>>> Looking at the differences between the ATs in the econo cars tested by
>>>> CR, Honda looks about as good as the other ATs (except for the CVT.)
>>> you're looking at fuel economy, right?
>>
>> Fuel economy was significantly better for the MTs but the biggest
>> difference was acceleration. The MTs blew the doors off the ATs. In
>> terms of 0 - 60 time differences, the Yaris AT was the best - "only"
>> 2.1 seconds slower than the MT version. Even the slowest MT car, the
>> Kia Rio was faster than the Versa CVT. The fastest AT car, the Yaris,
>> was 1.4 seconds slower than the Versa CVT.
>
>dude, compare like with like - not different car to different car if
>you're trying to compare trnasmissions, i.e. yaris with cvt, yaris with
>stick, etc. yaris stick to versa cvt doesn't work.
It doesn't matter whether you compare like to like or unlike to like.
All of the MTs are faster than all of the ATs and the CVT. Let me
tabulate it for you:
0-60 45-65 1/4 mi
Fit AT 12.4 8.4 19.0
Fit MT 9.9 6.5 17.4
Versa CVT 10.1 6.4 17.8
Versa MT 9.5 5.9 17.2
Rio AT 12.8 8.1 19.3
Rio MT 10.0 7.1 17.5
Accent AT 12.5 7.7 19.1
Accent MT 9.5 6.5 17.2
Yaris AT 11.4 6.9 18.6
Yaris MT 9.3 6.0 17.3
As I said, "The MTs blew the doors off the ATs."
>
>>
>>>>>>>> The ultimate "torque multiplier" is a CVT.
>>>>>>> that's different - it's not a torque multiplier.
>>>>>> Neither is the conventional AT, it just has a clever design to let the
>>>>>> engine speed up ahead of the vehicle speed without shifting. It is
>>>>>> basically like a limited range CVT.
>>>>> no dude, they're totally different. "torque multiplier" is something a
>>>>> torque converter can do - hence its name. everything else is ratio
>>>>> control, be it continuously variable or discrete.
>>>> OK, explain it to me. My understanding is that it is just a trick to
>>>> get the engine running at a slightly higher rpm to produce more power.
>>>> Kind of like a mini downshift. All car transmissions are torque
>>>> multipliers.
>>> ok, yes, but we're talking about different things. torque converters
>>> can increase torque output from a little to a lot in a very limited rev
>>> range. ratio change is something different and that's what the gears
>>> are for.
>>
>> You understand that the ATs torque output at a certain rpm (i.e. power
>> transmitted) is higher when the torque multiplication is active. There
>> are only two way this can happen. The first is to increase the
>> efficiency of the transmission. I think we can dismiss that. The
>> other way is to increase the power input.
>
>no, it depends on input/output speed differential. within certain rev
>ranges, torque transmission is very high, even with a rev differential.
> if it gets outside of that band, it drops right off.
http://en.wikipedia.org/wiki/Torque_...Multiplication
--quotes-- [my comments in brackets]
Unlike a fluid coupling, however, a torque converter is able to
multiply torque when there is a substantial difference between input
and output rotational speed, thus providing the equivalent of a
reduction gear. [IOW, a mini-downshift, a slightly lower gear that
allows the engine to run faster and produce more power.]
The principal difference is that whereas a fluid coupling is a two
element drive that is incapable of multiplying torque [IOW, it has a
1:1 ratio of input to output] , a torque converter has at least one
extra element - the stator - which alters the drive's characteristics
during periods of high slippage, producing an increase in output
torque. [IOW, it allows the engine to run faster and produce more
power, just like a lower gear.]
The Buick Dynaflow automatic transmission was a non-shifting design
and, under normal conditions, relied solely upon the converter to
multiply torque. [IOW, there was no gear transmission, all ratio
change was due to slippage of the TC - an early CVT!] The Dynaflow
used a five element converter to produce the wide range of torque
multiplication [i.e. wide range of drive ratios] needed to propel a
heavy vehicle.
* Acceleration. The load is accelerating but there still is a
relatively large difference between pump and turbine speed. [i.e. low
gear] ...The amount of multiplication will depend upon the actual
difference between pump and turbine speed, [i.e. the effective drive
ratio] as well as various other design factors. [efficiency]
* Coupling. The turbine has reached approximately 90 percent of
the speed of the pump. Torque multiplication has ceased [i.e. gear
ratio is slightly less than 1:1 but the slight power increase from
higher engine rpm is lost to inefficiency] and the torque converter is
behaving in a manner similar to a fluid coupling. In modern automotive
applications, it is usually at this stage of operation where the
lock-up clutch is applied, a procedure that tends to improve fuel
efficiency.
--end quotes--
When they say "torque multiplication" what they really mean is a drive
ratio less than 1:1. IOW, every transmission is a torque multiplier,
at least in the lower gears.
>
>> The only way to do that is
>> to increase the throttle opening or increase the rpm. The throttle
>> opening is determined by your foot (and it wouldn't be much of a trick
>> for the torque multiplier to be just an extra jerk on the throttle and
>> it wouldn't do much good if the throttle were already wide open.)
>> However, rpm is largely controlled by the transmission. The
>> transmission allows the engine to run a little faster and therefore
>> produce more power which is transmitted to the wheels. This is what I
>> meant by a mini downshift.
>
>that's the lockup clutch releasing.
Right, there is no torque multiplication in the TC unless it is
slipping.
>
>>
>>>> They take high rpm/low torque and turn it into low rpm
>>>> high torque. If it were perfectly efficient, the power output would
>>>> be equal to input but of course it is always less. No way to get more
>>>> power out unless you put more power in, i.e. run the engine at higher
>>>> rpm.
>>> see above.
>>>
>>>>>>> if is however a great
>>>>>>> way of achieving absolute optimum gear for all conditions.
>>>>>> I agree that it has a big theoretical advantage, especially compared
>>>>>> to a conventional AT.
>>>>> compared to /any/ transmission. there are mechanical efficiency issues
>>>>> with the friction interface, but that is more than outweighed by ratio
>>>>> flexibility and ability to keep the engine at its most efficient.
>>>> The why doesn't the Versa with a CVT get better mileage or accelerate
>>>> faster than the Versa with an MT? Unfortunately, there are few cars
>>>> which allow you to directly compare CVT vs. MT.
>>> civic hx was significantly more fuel efficient than the stick.
>>
>> I gather that was the CVT-equipped model. They don't sell it anymore.
>> I guess people hated it more than high fuel costs.
>
>my money's on dealer prejudice, not consumer. by the same token, the
>hatchback has been all but dropped in the u.s. afaikt, that's more to
>do with vehicles with the same utility selling for $30k rather than $15k
>for a hatch, not consumer demand. try buying a used hatchback civic
>here in the bay area - good luck! people just keep them - they never
>sell.
I personally like hatchbacks and I know they have a following. I too
am surprised and disappointed that they have all but disappeared. I
don't know I am ready to sign on to the conspiracy theory though. If
there were a strong market, Someone like Mazda or Nissan would jump to
serve it to increase their sales. apparently there isn't enough
demand to justify the high expense of two body styles and the sedan is
more popular.
I suppose I could blame the shortage of MTs on greedy dealers and
manufacturers who want to force me to buy a more expensive AT.
However, I am more inclined to blame Starbucks.
>>>>>>>> A lot of people don't like
>>>>>>>> them at all, but others say they get used to it. (The perception
>>>>>>>> problem is so bad that some manufacturers program virtual gears into
>>>>>>>> them thereby defeating the chief advantage of the CVT.)
>>>>>>> absolutely! i drove a "real" cvt one when i was in europe years ago,
>>>>>>> and yes it is /real/ weird at first. but it's amazing how much you can
>>>>>>> get out of a small 2-cylinder engine when it's got perfect gearing.
>>>>>>> quite fun! this particular model had 2 independent drives too, so not
>>>>>>> only did you have optimum gearing, you had limited slip diff benefits in
>>>>>>> snow & ice too.
>>>>>>> http://www.ritzsite.demon.nl/DAF/DAF_cars_p2.htm
>>>>>> That was the original CVT. Do you remember who offered the first CVT
>>>>>> in the US. (I don't think they ever sold the Daffodil here.)
>>>>> subaru?
>>>> That is what I recall. The car was called the Justy.
>>>>
>>>>>>>> I only rode
>>>>>>>> in one CVT car, a Nissan luxury sedan in Japan and it wasn't bad in
>>>>>>>> that application. He drove it fairly aggressively too - we hit almost
>>>>>>>> 180 kph on the expressway. I would like to try one of these. I don't
>>>>>>>> know if I would like it or not.
>>>>>>> if you're not used to traditional automatics, the transition is easy.
>>>>>>> if you're used to traditional autos, its weird for a few minutes because
>>>>>>> it doesn't "shift", but beyond that, they're actually very impressive.
>>>>>> Again though, I am not sure they are any faster or more efficient than
>>>>>> a good MT.
>>>>> well, the daf was only 650cc iirc, and 0-30, that wasn't much to touch it.
>>>> I think the Honda 600 would have blown its petals off. ;-)
>>>>
>>>>>> Consumer Reports tested the Versa with MT and with CVT.
>>>>>> The MT version was 0.6 seconds faster to 60 and got one more mpg. (And
>>>>>> CR panned that MT.) They also tested MT and (conventional) AT
>>>>>> versions of Fit, Rio, Accent and Yaris. In each case the MT was 2 - 3
>>>>>> seconds faster and got 2 more mpg, so the CVT was clearly better than
>>>>>> an AT but not as good as even a mediocre MT, at last on raw numbers.
>>>>> that depends on the management system. the modern cvt's "simulate" gear
>>>>> shifts which is the dumbest damned thing since it's not utilizing the
>>>>> inherent benefit of the system! on that basis, i'm not surprised.
>>>> Does the Versa do that? CR didn't mention it.
>>> don't know. given "consumer demand", i expect so.
>>
>> Like I said, they hate it just like you think I would. (Actually I
>> would love to try one, I do think it is a neat idea and it would be
>> fun for a while at least. Only after the novelty wore off could I
>> tell you if I like it or hate it. I actually suspect that I would
>> like it more than a conventional AT.)
>>
>> Here is an interesting review I found. (It indicates that the Versa
>> CVT does not have "gears," so the fact that it was slower and less
>> fuel efficient than the "clunky" MT is significant.) I made one
>> editorial comment in brackets.
>>
>> --quote--
>> But the CVT is the one that shines. Its proprietary design, benefiting
>> from Nissan's global cooperation with French carmaker Renault, is
>> uncanny in the way it maintains optimal engine rpm within the most
>> fuel-efficient torque range. It senses, for example, when the Versa is
>> proceeding downhill and glides effortlessly into a lower gear range to
>> slow the car with engine braking. [What if you don't want engine
>> braking? It is wasting kinetic energy = fuel.
>
>not correct. when engine braking, fuel delivery is completely stopped.
But kinetic energy is being lost. Doesn't matter if the car has to be
brought to a stop anyway, but if the driving situation requires little
or no compression braking and the computer orders a lot, the car will
slow unnecessarily and fuel will be consumed bringing it back up to
speed.
I use compression braking a lot. Sometimes I use a little, sometimes
I use a lot. Sometimes I coast with the clutch disengaged for maximum
distance. A transmission that always applies medium compression
braking is not as going to achieve the same thing.
>> What it needs in a
>> powerful computer with optical sensors to look ahead, evaluate the
>> situation and decide whether engine braking is advantageous
>
>why? i don't want my car making /that/ kind of decision. seriously,
But you are satisfied with it making the decision mindlessly. I agree
I do not want the car making that decision. I want to make it myself
and shift the transmission accordingly. My brain is the powerful
computer and my eyes are the optical sensors.
>auto engine braking only happens when you're foot braking - just like on
>a stick.
Not true. I use compression braking all the time with my foot off the
brake. Descending grades would be a prime example except that I live
in Chicago and there are no hills. Instead, I am the only guy in
crawling rush hour traffic not flashing his brake lights every 20
feet. It is way more fun than an AT if you play the game.
>you can't criticize what you've not used dude.
I am only pointing out that this feature has a down side. It might
not bother 95% of drivers, but it would bother me.
>
>>.]
>> Conversely, under pedal-to-the-floor acceleration, the CVT instantly
>> launches the engine to its max-torque rpm, then keeps it there
>> unchanged until a desired highway speed is reached.
>>
>> This goes against every traditional sensation of driving, wherein gear
>> changes trigger a momentary drop in rpm as the higher gear ratio is
>> engaged. There's a lot of mechanical inefficiency in that traditional
>> gear-change syncopation; and Versa's CVT eliminates it. When first
>> experiencing the CVT's behavior, it feels wrong, sounds noisy. In
>> truth, however, it's mostly the lack of noticeable gear changes that's
>> merely thwarting a driver's subconscious expectation of rising-falling
>> rpms as gears change.
>> --end quote--
>>
>> http://www.carlist.com/newcars/2007/ncr1116.html
>>
>>
>>>>>> And yet, there is hardly a proliferation of CVTs on the market. Most
>>>>>> of them seem to be on hybrids in fact.
>>>>> that's consumer and mechanic inertia - nothing to do with benefits or
>>>>> reliability. trust me on that one - i've driven the daf for an extended
>>>>> period and it's a great system.
>>>> Maybe. I would gladly trade the AT in my Ody for one if it was proven
>>>> reliable. Not all are. The on in the Saturn Vue was a disaster, but
>>>> I guess you have to expect that from GM. The Japanese units don't
>>>> seem to have any problems.
>>> i've never heard of problems with the civic hx.
>>
>> Neither have I, but then there aren't a lot out there.
>
>/all/ the 96-2000 hx autos are cvt.
Yes, but how many is that? If they had sold that many, it would still
be on the market. Don't get me wrong, I don't think they are any less
reliable than a conventional Civic AT, but I don't think there are
enough out there to really know for sure. They certainly aren't
terrible like the GM CVT.
<spamvortex@bad.example.net> wrote:
>Gordon McGrew wrote:
>> On Mon, 08 Jan 2007 21:25:13 -0800, jim beam
>> <spamvortex@bad.example.net> wrote:
>>
>>> Gordon McGrew wrote:
>>>> On Sun, 07 Jan 2007 15:20:11 -0800, jim beam
>>>> <spamvortex@bad.example.net> wrote:
>>>>
>>>>>>>>>> The problem with most (virtually all) ATs is that they are biased
>>>>>>>>>> toward automatic operation and discourage manual operation.
>>>>>>>>> how? my auto has the shift in exactly the same place as where the stick
>>>>>>>>> would be. i see no difference. the transmission even has a no-lock
>>>>>>>>> gate between 3rd & 4th [commonest manual override] especially so you
>>>>>>>>> /can/ flip up and down at will.
>>>>>>>> If you put it in 4, will it ever downshift into 3 by itself?
>>>>>>> yes, absolutely. it does it on "kickdown" acceleration /and/ it does it
>>>>>>> on braking. not gentle braking, but harder braking.
>>>>>> It is not a bad thing, I just don't care for it. If I want to
>>>>>> downshift, I can do that. If I don't want to, I don't like the car
>>>>>> doing it on its own.
>>>>> why not? it's just like you'd have on a stick.
>>>> Not sure I understand. My GS-R never downshifts on its own.
>>> if it doesn't, then there's something wrong. how old is it?
>>
>> It is a '94 with a 5-speed manual transmission. What kind of MT cars
>> have you driven that shift themselves???
>
>i misunderstood you.
>
>originally, you said "If I want to downshift, I can do that." well, you
>can on an auto. on my car, the shifter is in the same place as a stick
>would be too. and the auto replicates engine braking when you need it -
>just like you'd do yourself. really, it's a good system.
>
>>
>>
>>>>>>>> When you
>>>>>>>> shift into 3 does it effectively double clutch?
>>>>>>> pointless exercise on an automatic. but even then, on the modern autos,
>>>>>>> in conjunction with electronic throttle, yes, the engine revs /are/
>>>>>>> meshed to the gear on shift.
>>>>>> That is what I mean. I figured they had fixed that aspect which is
>>>>>> the worst part of the older ATs.
>>>>>>
>>>>>>>>>> Also, I
>>>>>>>>>> don't particularly care for the slippage of the torque converter.
>>>>>>>>> eh? what "slippage" is that? how does its mechanical function differ
>>>>>>>> >from a clutch [other than it has a much better efficiency range and is
>>>>>>>>> much smoother of course]?
>>>>>>>> Well, as you point out, I don't have any experience with modern high
>>>>>>>> end luxury cars, but I note that at least more modest cars generally
>>>>>>>> have a significantly greater 0-60 speed and a lower mpg rating. Since
>>>>>>>> they now mostly have five gears, I would assume that means they are
>>>>>>>> slipping.
>>>>>>> there's no slipping unless the lock-up clutch is released. see below.
>>>>>>>
>>>>>>>> Actually, the slipping is partly by design, the so-called
>>>>>>>> torque multiplier effect.
>>>>>>> yes, that's what a torque converter does.
>>>>>>>
>>>>>>>> Basically, if you are cruising along and
>>>>>>>> you give it a little gas, but not enough to force a downshift, you
>>>>>>>> will see the rpms jump up immediately.
>>>>>>> that's because the lockup clutch is released to allow more torque. more
>>>>>>> flexibility than a stick where you'd have to shift.
>>>>>> But that is the slippage. The engine speeds up races up ahead of any
>>>>>> change in vehicle speed.
>>>>> but i don't understand the problem - what's wrong with it? engines are
>>>>> not perfect across all rev ranges - why not let a computer manage the
>>>>> efficiency curves - for that's what's happening.
>>>> It is just a personal preference. I like the engine to be positively
>>>> coupled to the wheels.
>>> that's what the lockup clutch in the torque converter is for.
>>
>> But it isn't engaged all the time. When it disengages, that is when
>> it "slips" and I do not find that satisfying as a driver.
>
>you'd hate cvt. as i said before, there's zero relation between engine
>speed and vehicle speed - if you drive on engine revs, and it sounds
>like you do, you'll be suffering total loss of feedback.
>
>> Like I said
>> a the outside, it is a preference for MT. I like to drive cars and
>> the MT is more enjoyable than the ATs I have driven. I don't like it
>> shifting when I don't want it to and I don't like the slippy feel of
>> the torque converter. The fact that the MT is usually faster and more
>> fuel efficient is a bonus.
>
>check the modern civics in that department.
The AT Civic gets slightly better highway mileage than the MT - I am
guessing it may have a higher final ratio. The Accord 4 and V6 and
the Fit all get better mileage with the MT. I don't have any test
results, but I bet the MTs are universally faster (see below.)
>>>>>> It is like a slipping clutch. As for more
>>>>>> torque (horsepower really) a lot of that is eaten up by the
>>>>>> inefficiency of the torque converter.
>>>>> how is a slipping clutch more efficient? [it's not.]
>>>> No, I understand that (unlike a slipping clutch) there is a benefit to
>>>> the slip designed into the AT. I just don't like the feel of it and
>>>> the benefit is more than eaten up by the inefficiencies that come with
>>>> it.
>>> you'd hate cvt. there's no "relationship" between revs and engine speed
>>> at all.
>>
>> I think you are probably right. That is why I mentioned the fact that
>> the CVT isn't very popular in the US (if anywhere) and I think it is
>> because lots of people hate it. Why else would Honda sell a 7-speed
>> CVT?
>
>because they rely on dealer feedback, and dealers are morons? cvt was
>pretty popular in europe iirc. volvo sold them as well as daf, and they
>did quite well.
Why is that in the past tense? We agree they are more efficient than
conventional ATs and if they were popular, why didn't they drive
conventional ATs off the market? Reliability could have been an issue
but shouldn't be now (as long as you stay away form GM.)
>>
>> OTOH, it probably appeals to - or at least doesn't repulse - the
>> hybrid buyer because it befits the unconventional nature of the car. I
>> realize there are technical benefits to the combination of hybrid and
>> CVT, but I am saying that the unconventional nature of the CVT is less
>> of a negative when you are already committed to buying an
>> unconventional vehicle. If you are attracted to the hybrid because it
>> is unconventional, the CVT is a plus.
>
>nah, it's a pure engineering logic decision. cvt allows extremely good
>engine efficiency. if you don't want that, you don't want a hybrid.
Exactly right. The converse of that statement is that, if you want
increased efficiency, you will tolerate or even embrace the CVT. And
if you like the hybrid because it is odd or technologically advanced,
then you will love the CVT.
>>>>>> On cars where you can get a MT
>>>>>> or AT with the same engine, the MT is almost always faster and gets
>>>>>> better mileage.
>>>>> not so with the modern autos. and that's one of the big things about
>>>>> honda autos - it's basically a standard transmission with clutch packs
>>>>> instead of synchros. inherently more efficient than planetary gears.
>>>> Looking at the differences between the ATs in the econo cars tested by
>>>> CR, Honda looks about as good as the other ATs (except for the CVT.)
>>> you're looking at fuel economy, right?
>>
>> Fuel economy was significantly better for the MTs but the biggest
>> difference was acceleration. The MTs blew the doors off the ATs. In
>> terms of 0 - 60 time differences, the Yaris AT was the best - "only"
>> 2.1 seconds slower than the MT version. Even the slowest MT car, the
>> Kia Rio was faster than the Versa CVT. The fastest AT car, the Yaris,
>> was 1.4 seconds slower than the Versa CVT.
>
>dude, compare like with like - not different car to different car if
>you're trying to compare trnasmissions, i.e. yaris with cvt, yaris with
>stick, etc. yaris stick to versa cvt doesn't work.
It doesn't matter whether you compare like to like or unlike to like.
All of the MTs are faster than all of the ATs and the CVT. Let me
tabulate it for you:
0-60 45-65 1/4 mi
Fit AT 12.4 8.4 19.0
Fit MT 9.9 6.5 17.4
Versa CVT 10.1 6.4 17.8
Versa MT 9.5 5.9 17.2
Rio AT 12.8 8.1 19.3
Rio MT 10.0 7.1 17.5
Accent AT 12.5 7.7 19.1
Accent MT 9.5 6.5 17.2
Yaris AT 11.4 6.9 18.6
Yaris MT 9.3 6.0 17.3
As I said, "The MTs blew the doors off the ATs."
>
>>
>>>>>>>> The ultimate "torque multiplier" is a CVT.
>>>>>>> that's different - it's not a torque multiplier.
>>>>>> Neither is the conventional AT, it just has a clever design to let the
>>>>>> engine speed up ahead of the vehicle speed without shifting. It is
>>>>>> basically like a limited range CVT.
>>>>> no dude, they're totally different. "torque multiplier" is something a
>>>>> torque converter can do - hence its name. everything else is ratio
>>>>> control, be it continuously variable or discrete.
>>>> OK, explain it to me. My understanding is that it is just a trick to
>>>> get the engine running at a slightly higher rpm to produce more power.
>>>> Kind of like a mini downshift. All car transmissions are torque
>>>> multipliers.
>>> ok, yes, but we're talking about different things. torque converters
>>> can increase torque output from a little to a lot in a very limited rev
>>> range. ratio change is something different and that's what the gears
>>> are for.
>>
>> You understand that the ATs torque output at a certain rpm (i.e. power
>> transmitted) is higher when the torque multiplication is active. There
>> are only two way this can happen. The first is to increase the
>> efficiency of the transmission. I think we can dismiss that. The
>> other way is to increase the power input.
>
>no, it depends on input/output speed differential. within certain rev
>ranges, torque transmission is very high, even with a rev differential.
> if it gets outside of that band, it drops right off.
http://en.wikipedia.org/wiki/Torque_...Multiplication
--quotes-- [my comments in brackets]
Unlike a fluid coupling, however, a torque converter is able to
multiply torque when there is a substantial difference between input
and output rotational speed, thus providing the equivalent of a
reduction gear. [IOW, a mini-downshift, a slightly lower gear that
allows the engine to run faster and produce more power.]
The principal difference is that whereas a fluid coupling is a two
element drive that is incapable of multiplying torque [IOW, it has a
1:1 ratio of input to output] , a torque converter has at least one
extra element - the stator - which alters the drive's characteristics
during periods of high slippage, producing an increase in output
torque. [IOW, it allows the engine to run faster and produce more
power, just like a lower gear.]
The Buick Dynaflow automatic transmission was a non-shifting design
and, under normal conditions, relied solely upon the converter to
multiply torque. [IOW, there was no gear transmission, all ratio
change was due to slippage of the TC - an early CVT!] The Dynaflow
used a five element converter to produce the wide range of torque
multiplication [i.e. wide range of drive ratios] needed to propel a
heavy vehicle.
* Acceleration. The load is accelerating but there still is a
relatively large difference between pump and turbine speed. [i.e. low
gear] ...The amount of multiplication will depend upon the actual
difference between pump and turbine speed, [i.e. the effective drive
ratio] as well as various other design factors. [efficiency]
* Coupling. The turbine has reached approximately 90 percent of
the speed of the pump. Torque multiplication has ceased [i.e. gear
ratio is slightly less than 1:1 but the slight power increase from
higher engine rpm is lost to inefficiency] and the torque converter is
behaving in a manner similar to a fluid coupling. In modern automotive
applications, it is usually at this stage of operation where the
lock-up clutch is applied, a procedure that tends to improve fuel
efficiency.
--end quotes--
When they say "torque multiplication" what they really mean is a drive
ratio less than 1:1. IOW, every transmission is a torque multiplier,
at least in the lower gears.
>
>> The only way to do that is
>> to increase the throttle opening or increase the rpm. The throttle
>> opening is determined by your foot (and it wouldn't be much of a trick
>> for the torque multiplier to be just an extra jerk on the throttle and
>> it wouldn't do much good if the throttle were already wide open.)
>> However, rpm is largely controlled by the transmission. The
>> transmission allows the engine to run a little faster and therefore
>> produce more power which is transmitted to the wheels. This is what I
>> meant by a mini downshift.
>
>that's the lockup clutch releasing.
Right, there is no torque multiplication in the TC unless it is
slipping.
>
>>
>>>> They take high rpm/low torque and turn it into low rpm
>>>> high torque. If it were perfectly efficient, the power output would
>>>> be equal to input but of course it is always less. No way to get more
>>>> power out unless you put more power in, i.e. run the engine at higher
>>>> rpm.
>>> see above.
>>>
>>>>>>> if is however a great
>>>>>>> way of achieving absolute optimum gear for all conditions.
>>>>>> I agree that it has a big theoretical advantage, especially compared
>>>>>> to a conventional AT.
>>>>> compared to /any/ transmission. there are mechanical efficiency issues
>>>>> with the friction interface, but that is more than outweighed by ratio
>>>>> flexibility and ability to keep the engine at its most efficient.
>>>> The why doesn't the Versa with a CVT get better mileage or accelerate
>>>> faster than the Versa with an MT? Unfortunately, there are few cars
>>>> which allow you to directly compare CVT vs. MT.
>>> civic hx was significantly more fuel efficient than the stick.
>>
>> I gather that was the CVT-equipped model. They don't sell it anymore.
>> I guess people hated it more than high fuel costs.
>
>my money's on dealer prejudice, not consumer. by the same token, the
>hatchback has been all but dropped in the u.s. afaikt, that's more to
>do with vehicles with the same utility selling for $30k rather than $15k
>for a hatch, not consumer demand. try buying a used hatchback civic
>here in the bay area - good luck! people just keep them - they never
>sell.
I personally like hatchbacks and I know they have a following. I too
am surprised and disappointed that they have all but disappeared. I
don't know I am ready to sign on to the conspiracy theory though. If
there were a strong market, Someone like Mazda or Nissan would jump to
serve it to increase their sales. apparently there isn't enough
demand to justify the high expense of two body styles and the sedan is
more popular.
I suppose I could blame the shortage of MTs on greedy dealers and
manufacturers who want to force me to buy a more expensive AT.
However, I am more inclined to blame Starbucks.
>>>>>>>> A lot of people don't like
>>>>>>>> them at all, but others say they get used to it. (The perception
>>>>>>>> problem is so bad that some manufacturers program virtual gears into
>>>>>>>> them thereby defeating the chief advantage of the CVT.)
>>>>>>> absolutely! i drove a "real" cvt one when i was in europe years ago,
>>>>>>> and yes it is /real/ weird at first. but it's amazing how much you can
>>>>>>> get out of a small 2-cylinder engine when it's got perfect gearing.
>>>>>>> quite fun! this particular model had 2 independent drives too, so not
>>>>>>> only did you have optimum gearing, you had limited slip diff benefits in
>>>>>>> snow & ice too.
>>>>>>> http://www.ritzsite.demon.nl/DAF/DAF_cars_p2.htm
>>>>>> That was the original CVT. Do you remember who offered the first CVT
>>>>>> in the US. (I don't think they ever sold the Daffodil here.)
>>>>> subaru?
>>>> That is what I recall. The car was called the Justy.
>>>>
>>>>>>>> I only rode
>>>>>>>> in one CVT car, a Nissan luxury sedan in Japan and it wasn't bad in
>>>>>>>> that application. He drove it fairly aggressively too - we hit almost
>>>>>>>> 180 kph on the expressway. I would like to try one of these. I don't
>>>>>>>> know if I would like it or not.
>>>>>>> if you're not used to traditional automatics, the transition is easy.
>>>>>>> if you're used to traditional autos, its weird for a few minutes because
>>>>>>> it doesn't "shift", but beyond that, they're actually very impressive.
>>>>>> Again though, I am not sure they are any faster or more efficient than
>>>>>> a good MT.
>>>>> well, the daf was only 650cc iirc, and 0-30, that wasn't much to touch it.
>>>> I think the Honda 600 would have blown its petals off. ;-)
>>>>
>>>>>> Consumer Reports tested the Versa with MT and with CVT.
>>>>>> The MT version was 0.6 seconds faster to 60 and got one more mpg. (And
>>>>>> CR panned that MT.) They also tested MT and (conventional) AT
>>>>>> versions of Fit, Rio, Accent and Yaris. In each case the MT was 2 - 3
>>>>>> seconds faster and got 2 more mpg, so the CVT was clearly better than
>>>>>> an AT but not as good as even a mediocre MT, at last on raw numbers.
>>>>> that depends on the management system. the modern cvt's "simulate" gear
>>>>> shifts which is the dumbest damned thing since it's not utilizing the
>>>>> inherent benefit of the system! on that basis, i'm not surprised.
>>>> Does the Versa do that? CR didn't mention it.
>>> don't know. given "consumer demand", i expect so.
>>
>> Like I said, they hate it just like you think I would. (Actually I
>> would love to try one, I do think it is a neat idea and it would be
>> fun for a while at least. Only after the novelty wore off could I
>> tell you if I like it or hate it. I actually suspect that I would
>> like it more than a conventional AT.)
>>
>> Here is an interesting review I found. (It indicates that the Versa
>> CVT does not have "gears," so the fact that it was slower and less
>> fuel efficient than the "clunky" MT is significant.) I made one
>> editorial comment in brackets.
>>
>> --quote--
>> But the CVT is the one that shines. Its proprietary design, benefiting
>> from Nissan's global cooperation with French carmaker Renault, is
>> uncanny in the way it maintains optimal engine rpm within the most
>> fuel-efficient torque range. It senses, for example, when the Versa is
>> proceeding downhill and glides effortlessly into a lower gear range to
>> slow the car with engine braking. [What if you don't want engine
>> braking? It is wasting kinetic energy = fuel.
>
>not correct. when engine braking, fuel delivery is completely stopped.
But kinetic energy is being lost. Doesn't matter if the car has to be
brought to a stop anyway, but if the driving situation requires little
or no compression braking and the computer orders a lot, the car will
slow unnecessarily and fuel will be consumed bringing it back up to
speed.
I use compression braking a lot. Sometimes I use a little, sometimes
I use a lot. Sometimes I coast with the clutch disengaged for maximum
distance. A transmission that always applies medium compression
braking is not as going to achieve the same thing.
>> What it needs in a
>> powerful computer with optical sensors to look ahead, evaluate the
>> situation and decide whether engine braking is advantageous
>
>why? i don't want my car making /that/ kind of decision. seriously,
But you are satisfied with it making the decision mindlessly. I agree
I do not want the car making that decision. I want to make it myself
and shift the transmission accordingly. My brain is the powerful
computer and my eyes are the optical sensors.
>auto engine braking only happens when you're foot braking - just like on
>a stick.
Not true. I use compression braking all the time with my foot off the
brake. Descending grades would be a prime example except that I live
in Chicago and there are no hills. Instead, I am the only guy in
crawling rush hour traffic not flashing his brake lights every 20
feet. It is way more fun than an AT if you play the game.
>you can't criticize what you've not used dude.
I am only pointing out that this feature has a down side. It might
not bother 95% of drivers, but it would bother me.
>
>>.]
>> Conversely, under pedal-to-the-floor acceleration, the CVT instantly
>> launches the engine to its max-torque rpm, then keeps it there
>> unchanged until a desired highway speed is reached.
>>
>> This goes against every traditional sensation of driving, wherein gear
>> changes trigger a momentary drop in rpm as the higher gear ratio is
>> engaged. There's a lot of mechanical inefficiency in that traditional
>> gear-change syncopation; and Versa's CVT eliminates it. When first
>> experiencing the CVT's behavior, it feels wrong, sounds noisy. In
>> truth, however, it's mostly the lack of noticeable gear changes that's
>> merely thwarting a driver's subconscious expectation of rising-falling
>> rpms as gears change.
>> --end quote--
>>
>> http://www.carlist.com/newcars/2007/ncr1116.html
>>
>>
>>>>>> And yet, there is hardly a proliferation of CVTs on the market. Most
>>>>>> of them seem to be on hybrids in fact.
>>>>> that's consumer and mechanic inertia - nothing to do with benefits or
>>>>> reliability. trust me on that one - i've driven the daf for an extended
>>>>> period and it's a great system.
>>>> Maybe. I would gladly trade the AT in my Ody for one if it was proven
>>>> reliable. Not all are. The on in the Saturn Vue was a disaster, but
>>>> I guess you have to expect that from GM. The Japanese units don't
>>>> seem to have any problems.
>>> i've never heard of problems with the civic hx.
>>
>> Neither have I, but then there aren't a lot out there.
>
>/all/ the 96-2000 hx autos are cvt.
Yes, but how many is that? If they had sold that many, it would still
be on the market. Don't get me wrong, I don't think they are any less
reliable than a conventional Civic AT, but I don't think there are
enough out there to really know for sure. They certainly aren't
terrible like the GM CVT.
01-12-2007 | 12:50 AM
#97
Guest
Posts: n/a
Re: Transmission Activity
On Wed, 10 Jan 2007 20:43:45 -0800, jim beam
<spamvortex@bad.example.net> wrote:
>Gordon McGrew wrote:
>> On Mon, 08 Jan 2007 21:25:13 -0800, jim beam
>> <spamvortex@bad.example.net> wrote:
>>
>>> Gordon McGrew wrote:
>>>> On Sun, 07 Jan 2007 15:20:11 -0800, jim beam
>>>> <spamvortex@bad.example.net> wrote:
>>>>
>>>>>>>>>> The problem with most (virtually all) ATs is that they are biased
>>>>>>>>>> toward automatic operation and discourage manual operation.
>>>>>>>>> how? my auto has the shift in exactly the same place as where the stick
>>>>>>>>> would be. i see no difference. the transmission even has a no-lock
>>>>>>>>> gate between 3rd & 4th [commonest manual override] especially so you
>>>>>>>>> /can/ flip up and down at will.
>>>>>>>> If you put it in 4, will it ever downshift into 3 by itself?
>>>>>>> yes, absolutely. it does it on "kickdown" acceleration /and/ it does it
>>>>>>> on braking. not gentle braking, but harder braking.
>>>>>> It is not a bad thing, I just don't care for it. If I want to
>>>>>> downshift, I can do that. If I don't want to, I don't like the car
>>>>>> doing it on its own.
>>>>> why not? it's just like you'd have on a stick.
>>>> Not sure I understand. My GS-R never downshifts on its own.
>>> if it doesn't, then there's something wrong. how old is it?
>>
>> It is a '94 with a 5-speed manual transmission. What kind of MT cars
>> have you driven that shift themselves???
>
>i misunderstood you.
>
>originally, you said "If I want to downshift, I can do that." well, you
>can on an auto. on my car, the shifter is in the same place as a stick
>would be too. and the auto replicates engine braking when you need it -
>just like you'd do yourself. really, it's a good system.
>
>>
>>
>>>>>>>> When you
>>>>>>>> shift into 3 does it effectively double clutch?
>>>>>>> pointless exercise on an automatic. but even then, on the modern autos,
>>>>>>> in conjunction with electronic throttle, yes, the engine revs /are/
>>>>>>> meshed to the gear on shift.
>>>>>> That is what I mean. I figured they had fixed that aspect which is
>>>>>> the worst part of the older ATs.
>>>>>>
>>>>>>>>>> Also, I
>>>>>>>>>> don't particularly care for the slippage of the torque converter.
>>>>>>>>> eh? what "slippage" is that? how does its mechanical function differ
>>>>>>>> >from a clutch [other than it has a much better efficiency range and is
>>>>>>>>> much smoother of course]?
>>>>>>>> Well, as you point out, I don't have any experience with modern high
>>>>>>>> end luxury cars, but I note that at least more modest cars generally
>>>>>>>> have a significantly greater 0-60 speed and a lower mpg rating. Since
>>>>>>>> they now mostly have five gears, I would assume that means they are
>>>>>>>> slipping.
>>>>>>> there's no slipping unless the lock-up clutch is released. see below.
>>>>>>>
>>>>>>>> Actually, the slipping is partly by design, the so-called
>>>>>>>> torque multiplier effect.
>>>>>>> yes, that's what a torque converter does.
>>>>>>>
>>>>>>>> Basically, if you are cruising along and
>>>>>>>> you give it a little gas, but not enough to force a downshift, you
>>>>>>>> will see the rpms jump up immediately.
>>>>>>> that's because the lockup clutch is released to allow more torque. more
>>>>>>> flexibility than a stick where you'd have to shift.
>>>>>> But that is the slippage. The engine speeds up races up ahead of any
>>>>>> change in vehicle speed.
>>>>> but i don't understand the problem - what's wrong with it? engines are
>>>>> not perfect across all rev ranges - why not let a computer manage the
>>>>> efficiency curves - for that's what's happening.
>>>> It is just a personal preference. I like the engine to be positively
>>>> coupled to the wheels.
>>> that's what the lockup clutch in the torque converter is for.
>>
>> But it isn't engaged all the time. When it disengages, that is when
>> it "slips" and I do not find that satisfying as a driver.
>
>you'd hate cvt. as i said before, there's zero relation between engine
>speed and vehicle speed - if you drive on engine revs, and it sounds
>like you do, you'll be suffering total loss of feedback.
>
>> Like I said
>> a the outside, it is a preference for MT. I like to drive cars and
>> the MT is more enjoyable than the ATs I have driven. I don't like it
>> shifting when I don't want it to and I don't like the slippy feel of
>> the torque converter. The fact that the MT is usually faster and more
>> fuel efficient is a bonus.
>
>check the modern civics in that department.
The AT Civic gets slightly better highway mileage than the MT - I am
guessing it may have a higher final ratio. The Accord 4 and V6 and
the Fit all get better mileage with the MT. I don't have any test
results, but I bet the MTs are universally faster (see below.)
>>>>>> It is like a slipping clutch. As for more
>>>>>> torque (horsepower really) a lot of that is eaten up by the
>>>>>> inefficiency of the torque converter.
>>>>> how is a slipping clutch more efficient? [it's not.]
>>>> No, I understand that (unlike a slipping clutch) there is a benefit to
>>>> the slip designed into the AT. I just don't like the feel of it and
>>>> the benefit is more than eaten up by the inefficiencies that come with
>>>> it.
>>> you'd hate cvt. there's no "relationship" between revs and engine speed
>>> at all.
>>
>> I think you are probably right. That is why I mentioned the fact that
>> the CVT isn't very popular in the US (if anywhere) and I think it is
>> because lots of people hate it. Why else would Honda sell a 7-speed
>> CVT?
>
>because they rely on dealer feedback, and dealers are morons? cvt was
>pretty popular in europe iirc. volvo sold them as well as daf, and they
>did quite well.
Why is that in the past tense? We agree they are more efficient than
conventional ATs and if they were popular, why didn't they drive
conventional ATs off the market? Reliability could have been an issue
but shouldn't be now (as long as you stay away form GM.)
>>
>> OTOH, it probably appeals to - or at least doesn't repulse - the
>> hybrid buyer because it befits the unconventional nature of the car. I
>> realize there are technical benefits to the combination of hybrid and
>> CVT, but I am saying that the unconventional nature of the CVT is less
>> of a negative when you are already committed to buying an
>> unconventional vehicle. If you are attracted to the hybrid because it
>> is unconventional, the CVT is a plus.
>
>nah, it's a pure engineering logic decision. cvt allows extremely good
>engine efficiency. if you don't want that, you don't want a hybrid.
Exactly right. The converse of that statement is that, if you want
increased efficiency, you will tolerate or even embrace the CVT. And
if you like the hybrid because it is odd or technologically advanced,
then you will love the CVT.
>>>>>> On cars where you can get a MT
>>>>>> or AT with the same engine, the MT is almost always faster and gets
>>>>>> better mileage.
>>>>> not so with the modern autos. and that's one of the big things about
>>>>> honda autos - it's basically a standard transmission with clutch packs
>>>>> instead of synchros. inherently more efficient than planetary gears.
>>>> Looking at the differences between the ATs in the econo cars tested by
>>>> CR, Honda looks about as good as the other ATs (except for the CVT.)
>>> you're looking at fuel economy, right?
>>
>> Fuel economy was significantly better for the MTs but the biggest
>> difference was acceleration. The MTs blew the doors off the ATs. In
>> terms of 0 - 60 time differences, the Yaris AT was the best - "only"
>> 2.1 seconds slower than the MT version. Even the slowest MT car, the
>> Kia Rio was faster than the Versa CVT. The fastest AT car, the Yaris,
>> was 1.4 seconds slower than the Versa CVT.
>
>dude, compare like with like - not different car to different car if
>you're trying to compare trnasmissions, i.e. yaris with cvt, yaris with
>stick, etc. yaris stick to versa cvt doesn't work.
It doesn't matter whether you compare like to like or unlike to like.
All of the MTs are faster than all of the ATs and the CVT. Let me
tabulate it for you:
0-60 45-65 1/4 mi
Fit AT 12.4 8.4 19.0
Fit MT 9.9 6.5 17.4
Versa CVT 10.1 6.4 17.8
Versa MT 9.5 5.9 17.2
Rio AT 12.8 8.1 19.3
Rio MT 10.0 7.1 17.5
Accent AT 12.5 7.7 19.1
Accent MT 9.5 6.5 17.2
Yaris AT 11.4 6.9 18.6
Yaris MT 9.3 6.0 17.3
As I said, "The MTs blew the doors off the ATs."
>
>>
>>>>>>>> The ultimate "torque multiplier" is a CVT.
>>>>>>> that's different - it's not a torque multiplier.
>>>>>> Neither is the conventional AT, it just has a clever design to let the
>>>>>> engine speed up ahead of the vehicle speed without shifting. It is
>>>>>> basically like a limited range CVT.
>>>>> no dude, they're totally different. "torque multiplier" is something a
>>>>> torque converter can do - hence its name. everything else is ratio
>>>>> control, be it continuously variable or discrete.
>>>> OK, explain it to me. My understanding is that it is just a trick to
>>>> get the engine running at a slightly higher rpm to produce more power.
>>>> Kind of like a mini downshift. All car transmissions are torque
>>>> multipliers.
>>> ok, yes, but we're talking about different things. torque converters
>>> can increase torque output from a little to a lot in a very limited rev
>>> range. ratio change is something different and that's what the gears
>>> are for.
>>
>> You understand that the ATs torque output at a certain rpm (i.e. power
>> transmitted) is higher when the torque multiplication is active. There
>> are only two way this can happen. The first is to increase the
>> efficiency of the transmission. I think we can dismiss that. The
>> other way is to increase the power input.
>
>no, it depends on input/output speed differential. within certain rev
>ranges, torque transmission is very high, even with a rev differential.
> if it gets outside of that band, it drops right off.
http://en.wikipedia.org/wiki/Torque_...Multiplication
--quotes-- [my comments in brackets]
Unlike a fluid coupling, however, a torque converter is able to
multiply torque when there is a substantial difference between input
and output rotational speed, thus providing the equivalent of a
reduction gear. [IOW, a mini-downshift, a slightly lower gear that
allows the engine to run faster and produce more power.]
The principal difference is that whereas a fluid coupling is a two
element drive that is incapable of multiplying torque [IOW, it has a
1:1 ratio of input to output] , a torque converter has at least one
extra element - the stator - which alters the drive's characteristics
during periods of high slippage, producing an increase in output
torque. [IOW, it allows the engine to run faster and produce more
power, just like a lower gear.]
The Buick Dynaflow automatic transmission was a non-shifting design
and, under normal conditions, relied solely upon the converter to
multiply torque. [IOW, there was no gear transmission, all ratio
change was due to slippage of the TC - an early CVT!] The Dynaflow
used a five element converter to produce the wide range of torque
multiplication [i.e. wide range of drive ratios] needed to propel a
heavy vehicle.
* Acceleration. The load is accelerating but there still is a
relatively large difference between pump and turbine speed. [i.e. low
gear] ...The amount of multiplication will depend upon the actual
difference between pump and turbine speed, [i.e. the effective drive
ratio] as well as various other design factors. [efficiency]
* Coupling. The turbine has reached approximately 90 percent of
the speed of the pump. Torque multiplication has ceased [i.e. gear
ratio is slightly less than 1:1 but the slight power increase from
higher engine rpm is lost to inefficiency] and the torque converter is
behaving in a manner similar to a fluid coupling. In modern automotive
applications, it is usually at this stage of operation where the
lock-up clutch is applied, a procedure that tends to improve fuel
efficiency.
--end quotes--
When they say "torque multiplication" what they really mean is a drive
ratio less than 1:1. IOW, every transmission is a torque multiplier,
at least in the lower gears.
>
>> The only way to do that is
>> to increase the throttle opening or increase the rpm. The throttle
>> opening is determined by your foot (and it wouldn't be much of a trick
>> for the torque multiplier to be just an extra jerk on the throttle and
>> it wouldn't do much good if the throttle were already wide open.)
>> However, rpm is largely controlled by the transmission. The
>> transmission allows the engine to run a little faster and therefore
>> produce more power which is transmitted to the wheels. This is what I
>> meant by a mini downshift.
>
>that's the lockup clutch releasing.
Right, there is no torque multiplication in the TC unless it is
slipping.
>
>>
>>>> They take high rpm/low torque and turn it into low rpm
>>>> high torque. If it were perfectly efficient, the power output would
>>>> be equal to input but of course it is always less. No way to get more
>>>> power out unless you put more power in, i.e. run the engine at higher
>>>> rpm.
>>> see above.
>>>
>>>>>>> if is however a great
>>>>>>> way of achieving absolute optimum gear for all conditions.
>>>>>> I agree that it has a big theoretical advantage, especially compared
>>>>>> to a conventional AT.
>>>>> compared to /any/ transmission. there are mechanical efficiency issues
>>>>> with the friction interface, but that is more than outweighed by ratio
>>>>> flexibility and ability to keep the engine at its most efficient.
>>>> The why doesn't the Versa with a CVT get better mileage or accelerate
>>>> faster than the Versa with an MT? Unfortunately, there are few cars
>>>> which allow you to directly compare CVT vs. MT.
>>> civic hx was significantly more fuel efficient than the stick.
>>
>> I gather that was the CVT-equipped model. They don't sell it anymore.
>> I guess people hated it more than high fuel costs.
>
>my money's on dealer prejudice, not consumer. by the same token, the
>hatchback has been all but dropped in the u.s. afaikt, that's more to
>do with vehicles with the same utility selling for $30k rather than $15k
>for a hatch, not consumer demand. try buying a used hatchback civic
>here in the bay area - good luck! people just keep them - they never
>sell.
I personally like hatchbacks and I know they have a following. I too
am surprised and disappointed that they have all but disappeared. I
don't know I am ready to sign on to the conspiracy theory though. If
there were a strong market, Someone like Mazda or Nissan would jump to
serve it to increase their sales. apparently there isn't enough
demand to justify the high expense of two body styles and the sedan is
more popular.
I suppose I could blame the shortage of MTs on greedy dealers and
manufacturers who want to force me to buy a more expensive AT.
However, I am more inclined to blame Starbucks.
>>>>>>>> A lot of people don't like
>>>>>>>> them at all, but others say they get used to it. (The perception
>>>>>>>> problem is so bad that some manufacturers program virtual gears into
>>>>>>>> them thereby defeating the chief advantage of the CVT.)
>>>>>>> absolutely! i drove a "real" cvt one when i was in europe years ago,
>>>>>>> and yes it is /real/ weird at first. but it's amazing how much you can
>>>>>>> get out of a small 2-cylinder engine when it's got perfect gearing.
>>>>>>> quite fun! this particular model had 2 independent drives too, so not
>>>>>>> only did you have optimum gearing, you had limited slip diff benefits in
>>>>>>> snow & ice too.
>>>>>>> http://www.ritzsite.demon.nl/DAF/DAF_cars_p2.htm
>>>>>> That was the original CVT. Do you remember who offered the first CVT
>>>>>> in the US. (I don't think they ever sold the Daffodil here.)
>>>>> subaru?
>>>> That is what I recall. The car was called the Justy.
>>>>
>>>>>>>> I only rode
>>>>>>>> in one CVT car, a Nissan luxury sedan in Japan and it wasn't bad in
>>>>>>>> that application. He drove it fairly aggressively too - we hit almost
>>>>>>>> 180 kph on the expressway. I would like to try one of these. I don't
>>>>>>>> know if I would like it or not.
>>>>>>> if you're not used to traditional automatics, the transition is easy.
>>>>>>> if you're used to traditional autos, its weird for a few minutes because
>>>>>>> it doesn't "shift", but beyond that, they're actually very impressive.
>>>>>> Again though, I am not sure they are any faster or more efficient than
>>>>>> a good MT.
>>>>> well, the daf was only 650cc iirc, and 0-30, that wasn't much to touch it.
>>>> I think the Honda 600 would have blown its petals off. ;-)
>>>>
>>>>>> Consumer Reports tested the Versa with MT and with CVT.
>>>>>> The MT version was 0.6 seconds faster to 60 and got one more mpg. (And
>>>>>> CR panned that MT.) They also tested MT and (conventional) AT
>>>>>> versions of Fit, Rio, Accent and Yaris. In each case the MT was 2 - 3
>>>>>> seconds faster and got 2 more mpg, so the CVT was clearly better than
>>>>>> an AT but not as good as even a mediocre MT, at last on raw numbers.
>>>>> that depends on the management system. the modern cvt's "simulate" gear
>>>>> shifts which is the dumbest damned thing since it's not utilizing the
>>>>> inherent benefit of the system! on that basis, i'm not surprised.
>>>> Does the Versa do that? CR didn't mention it.
>>> don't know. given "consumer demand", i expect so.
>>
>> Like I said, they hate it just like you think I would. (Actually I
>> would love to try one, I do think it is a neat idea and it would be
>> fun for a while at least. Only after the novelty wore off could I
>> tell you if I like it or hate it. I actually suspect that I would
>> like it more than a conventional AT.)
>>
>> Here is an interesting review I found. (It indicates that the Versa
>> CVT does not have "gears," so the fact that it was slower and less
>> fuel efficient than the "clunky" MT is significant.) I made one
>> editorial comment in brackets.
>>
>> --quote--
>> But the CVT is the one that shines. Its proprietary design, benefiting
>> from Nissan's global cooperation with French carmaker Renault, is
>> uncanny in the way it maintains optimal engine rpm within the most
>> fuel-efficient torque range. It senses, for example, when the Versa is
>> proceeding downhill and glides effortlessly into a lower gear range to
>> slow the car with engine braking. [What if you don't want engine
>> braking? It is wasting kinetic energy = fuel.
>
>not correct. when engine braking, fuel delivery is completely stopped.
But kinetic energy is being lost. Doesn't matter if the car has to be
brought to a stop anyway, but if the driving situation requires little
or no compression braking and the computer orders a lot, the car will
slow unnecessarily and fuel will be consumed bringing it back up to
speed.
I use compression braking a lot. Sometimes I use a little, sometimes
I use a lot. Sometimes I coast with the clutch disengaged for maximum
distance. A transmission that always applies medium compression
braking is not as going to achieve the same thing.
>> What it needs in a
>> powerful computer with optical sensors to look ahead, evaluate the
>> situation and decide whether engine braking is advantageous
>
>why? i don't want my car making /that/ kind of decision. seriously,
But you are satisfied with it making the decision mindlessly. I agree
I do not want the car making that decision. I want to make it myself
and shift the transmission accordingly. My brain is the powerful
computer and my eyes are the optical sensors.
>auto engine braking only happens when you're foot braking - just like on
>a stick.
Not true. I use compression braking all the time with my foot off the
brake. Descending grades would be a prime example except that I live
in Chicago and there are no hills. Instead, I am the only guy in
crawling rush hour traffic not flashing his brake lights every 20
feet. It is way more fun than an AT if you play the game.
>you can't criticize what you've not used dude.
I am only pointing out that this feature has a down side. It might
not bother 95% of drivers, but it would bother me.
>
>>.]
>> Conversely, under pedal-to-the-floor acceleration, the CVT instantly
>> launches the engine to its max-torque rpm, then keeps it there
>> unchanged until a desired highway speed is reached.
>>
>> This goes against every traditional sensation of driving, wherein gear
>> changes trigger a momentary drop in rpm as the higher gear ratio is
>> engaged. There's a lot of mechanical inefficiency in that traditional
>> gear-change syncopation; and Versa's CVT eliminates it. When first
>> experiencing the CVT's behavior, it feels wrong, sounds noisy. In
>> truth, however, it's mostly the lack of noticeable gear changes that's
>> merely thwarting a driver's subconscious expectation of rising-falling
>> rpms as gears change.
>> --end quote--
>>
>> http://www.carlist.com/newcars/2007/ncr1116.html
>>
>>
>>>>>> And yet, there is hardly a proliferation of CVTs on the market. Most
>>>>>> of them seem to be on hybrids in fact.
>>>>> that's consumer and mechanic inertia - nothing to do with benefits or
>>>>> reliability. trust me on that one - i've driven the daf for an extended
>>>>> period and it's a great system.
>>>> Maybe. I would gladly trade the AT in my Ody for one if it was proven
>>>> reliable. Not all are. The on in the Saturn Vue was a disaster, but
>>>> I guess you have to expect that from GM. The Japanese units don't
>>>> seem to have any problems.
>>> i've never heard of problems with the civic hx.
>>
>> Neither have I, but then there aren't a lot out there.
>
>/all/ the 96-2000 hx autos are cvt.
Yes, but how many is that? If they had sold that many, it would still
be on the market. Don't get me wrong, I don't think they are any less
reliable than a conventional Civic AT, but I don't think there are
enough out there to really know for sure. They certainly aren't
terrible like the GM CVT.
<spamvortex@bad.example.net> wrote:
>Gordon McGrew wrote:
>> On Mon, 08 Jan 2007 21:25:13 -0800, jim beam
>> <spamvortex@bad.example.net> wrote:
>>
>>> Gordon McGrew wrote:
>>>> On Sun, 07 Jan 2007 15:20:11 -0800, jim beam
>>>> <spamvortex@bad.example.net> wrote:
>>>>
>>>>>>>>>> The problem with most (virtually all) ATs is that they are biased
>>>>>>>>>> toward automatic operation and discourage manual operation.
>>>>>>>>> how? my auto has the shift in exactly the same place as where the stick
>>>>>>>>> would be. i see no difference. the transmission even has a no-lock
>>>>>>>>> gate between 3rd & 4th [commonest manual override] especially so you
>>>>>>>>> /can/ flip up and down at will.
>>>>>>>> If you put it in 4, will it ever downshift into 3 by itself?
>>>>>>> yes, absolutely. it does it on "kickdown" acceleration /and/ it does it
>>>>>>> on braking. not gentle braking, but harder braking.
>>>>>> It is not a bad thing, I just don't care for it. If I want to
>>>>>> downshift, I can do that. If I don't want to, I don't like the car
>>>>>> doing it on its own.
>>>>> why not? it's just like you'd have on a stick.
>>>> Not sure I understand. My GS-R never downshifts on its own.
>>> if it doesn't, then there's something wrong. how old is it?
>>
>> It is a '94 with a 5-speed manual transmission. What kind of MT cars
>> have you driven that shift themselves???
>
>i misunderstood you.
>
>originally, you said "If I want to downshift, I can do that." well, you
>can on an auto. on my car, the shifter is in the same place as a stick
>would be too. and the auto replicates engine braking when you need it -
>just like you'd do yourself. really, it's a good system.
>
>>
>>
>>>>>>>> When you
>>>>>>>> shift into 3 does it effectively double clutch?
>>>>>>> pointless exercise on an automatic. but even then, on the modern autos,
>>>>>>> in conjunction with electronic throttle, yes, the engine revs /are/
>>>>>>> meshed to the gear on shift.
>>>>>> That is what I mean. I figured they had fixed that aspect which is
>>>>>> the worst part of the older ATs.
>>>>>>
>>>>>>>>>> Also, I
>>>>>>>>>> don't particularly care for the slippage of the torque converter.
>>>>>>>>> eh? what "slippage" is that? how does its mechanical function differ
>>>>>>>> >from a clutch [other than it has a much better efficiency range and is
>>>>>>>>> much smoother of course]?
>>>>>>>> Well, as you point out, I don't have any experience with modern high
>>>>>>>> end luxury cars, but I note that at least more modest cars generally
>>>>>>>> have a significantly greater 0-60 speed and a lower mpg rating. Since
>>>>>>>> they now mostly have five gears, I would assume that means they are
>>>>>>>> slipping.
>>>>>>> there's no slipping unless the lock-up clutch is released. see below.
>>>>>>>
>>>>>>>> Actually, the slipping is partly by design, the so-called
>>>>>>>> torque multiplier effect.
>>>>>>> yes, that's what a torque converter does.
>>>>>>>
>>>>>>>> Basically, if you are cruising along and
>>>>>>>> you give it a little gas, but not enough to force a downshift, you
>>>>>>>> will see the rpms jump up immediately.
>>>>>>> that's because the lockup clutch is released to allow more torque. more
>>>>>>> flexibility than a stick where you'd have to shift.
>>>>>> But that is the slippage. The engine speeds up races up ahead of any
>>>>>> change in vehicle speed.
>>>>> but i don't understand the problem - what's wrong with it? engines are
>>>>> not perfect across all rev ranges - why not let a computer manage the
>>>>> efficiency curves - for that's what's happening.
>>>> It is just a personal preference. I like the engine to be positively
>>>> coupled to the wheels.
>>> that's what the lockup clutch in the torque converter is for.
>>
>> But it isn't engaged all the time. When it disengages, that is when
>> it "slips" and I do not find that satisfying as a driver.
>
>you'd hate cvt. as i said before, there's zero relation between engine
>speed and vehicle speed - if you drive on engine revs, and it sounds
>like you do, you'll be suffering total loss of feedback.
>
>> Like I said
>> a the outside, it is a preference for MT. I like to drive cars and
>> the MT is more enjoyable than the ATs I have driven. I don't like it
>> shifting when I don't want it to and I don't like the slippy feel of
>> the torque converter. The fact that the MT is usually faster and more
>> fuel efficient is a bonus.
>
>check the modern civics in that department.
The AT Civic gets slightly better highway mileage than the MT - I am
guessing it may have a higher final ratio. The Accord 4 and V6 and
the Fit all get better mileage with the MT. I don't have any test
results, but I bet the MTs are universally faster (see below.)
>>>>>> It is like a slipping clutch. As for more
>>>>>> torque (horsepower really) a lot of that is eaten up by the
>>>>>> inefficiency of the torque converter.
>>>>> how is a slipping clutch more efficient? [it's not.]
>>>> No, I understand that (unlike a slipping clutch) there is a benefit to
>>>> the slip designed into the AT. I just don't like the feel of it and
>>>> the benefit is more than eaten up by the inefficiencies that come with
>>>> it.
>>> you'd hate cvt. there's no "relationship" between revs and engine speed
>>> at all.
>>
>> I think you are probably right. That is why I mentioned the fact that
>> the CVT isn't very popular in the US (if anywhere) and I think it is
>> because lots of people hate it. Why else would Honda sell a 7-speed
>> CVT?
>
>because they rely on dealer feedback, and dealers are morons? cvt was
>pretty popular in europe iirc. volvo sold them as well as daf, and they
>did quite well.
Why is that in the past tense? We agree they are more efficient than
conventional ATs and if they were popular, why didn't they drive
conventional ATs off the market? Reliability could have been an issue
but shouldn't be now (as long as you stay away form GM.)
>>
>> OTOH, it probably appeals to - or at least doesn't repulse - the
>> hybrid buyer because it befits the unconventional nature of the car. I
>> realize there are technical benefits to the combination of hybrid and
>> CVT, but I am saying that the unconventional nature of the CVT is less
>> of a negative when you are already committed to buying an
>> unconventional vehicle. If you are attracted to the hybrid because it
>> is unconventional, the CVT is a plus.
>
>nah, it's a pure engineering logic decision. cvt allows extremely good
>engine efficiency. if you don't want that, you don't want a hybrid.
Exactly right. The converse of that statement is that, if you want
increased efficiency, you will tolerate or even embrace the CVT. And
if you like the hybrid because it is odd or technologically advanced,
then you will love the CVT.
>>>>>> On cars where you can get a MT
>>>>>> or AT with the same engine, the MT is almost always faster and gets
>>>>>> better mileage.
>>>>> not so with the modern autos. and that's one of the big things about
>>>>> honda autos - it's basically a standard transmission with clutch packs
>>>>> instead of synchros. inherently more efficient than planetary gears.
>>>> Looking at the differences between the ATs in the econo cars tested by
>>>> CR, Honda looks about as good as the other ATs (except for the CVT.)
>>> you're looking at fuel economy, right?
>>
>> Fuel economy was significantly better for the MTs but the biggest
>> difference was acceleration. The MTs blew the doors off the ATs. In
>> terms of 0 - 60 time differences, the Yaris AT was the best - "only"
>> 2.1 seconds slower than the MT version. Even the slowest MT car, the
>> Kia Rio was faster than the Versa CVT. The fastest AT car, the Yaris,
>> was 1.4 seconds slower than the Versa CVT.
>
>dude, compare like with like - not different car to different car if
>you're trying to compare trnasmissions, i.e. yaris with cvt, yaris with
>stick, etc. yaris stick to versa cvt doesn't work.
It doesn't matter whether you compare like to like or unlike to like.
All of the MTs are faster than all of the ATs and the CVT. Let me
tabulate it for you:
0-60 45-65 1/4 mi
Fit AT 12.4 8.4 19.0
Fit MT 9.9 6.5 17.4
Versa CVT 10.1 6.4 17.8
Versa MT 9.5 5.9 17.2
Rio AT 12.8 8.1 19.3
Rio MT 10.0 7.1 17.5
Accent AT 12.5 7.7 19.1
Accent MT 9.5 6.5 17.2
Yaris AT 11.4 6.9 18.6
Yaris MT 9.3 6.0 17.3
As I said, "The MTs blew the doors off the ATs."
>
>>
>>>>>>>> The ultimate "torque multiplier" is a CVT.
>>>>>>> that's different - it's not a torque multiplier.
>>>>>> Neither is the conventional AT, it just has a clever design to let the
>>>>>> engine speed up ahead of the vehicle speed without shifting. It is
>>>>>> basically like a limited range CVT.
>>>>> no dude, they're totally different. "torque multiplier" is something a
>>>>> torque converter can do - hence its name. everything else is ratio
>>>>> control, be it continuously variable or discrete.
>>>> OK, explain it to me. My understanding is that it is just a trick to
>>>> get the engine running at a slightly higher rpm to produce more power.
>>>> Kind of like a mini downshift. All car transmissions are torque
>>>> multipliers.
>>> ok, yes, but we're talking about different things. torque converters
>>> can increase torque output from a little to a lot in a very limited rev
>>> range. ratio change is something different and that's what the gears
>>> are for.
>>
>> You understand that the ATs torque output at a certain rpm (i.e. power
>> transmitted) is higher when the torque multiplication is active. There
>> are only two way this can happen. The first is to increase the
>> efficiency of the transmission. I think we can dismiss that. The
>> other way is to increase the power input.
>
>no, it depends on input/output speed differential. within certain rev
>ranges, torque transmission is very high, even with a rev differential.
> if it gets outside of that band, it drops right off.
http://en.wikipedia.org/wiki/Torque_...Multiplication
--quotes-- [my comments in brackets]
Unlike a fluid coupling, however, a torque converter is able to
multiply torque when there is a substantial difference between input
and output rotational speed, thus providing the equivalent of a
reduction gear. [IOW, a mini-downshift, a slightly lower gear that
allows the engine to run faster and produce more power.]
The principal difference is that whereas a fluid coupling is a two
element drive that is incapable of multiplying torque [IOW, it has a
1:1 ratio of input to output] , a torque converter has at least one
extra element - the stator - which alters the drive's characteristics
during periods of high slippage, producing an increase in output
torque. [IOW, it allows the engine to run faster and produce more
power, just like a lower gear.]
The Buick Dynaflow automatic transmission was a non-shifting design
and, under normal conditions, relied solely upon the converter to
multiply torque. [IOW, there was no gear transmission, all ratio
change was due to slippage of the TC - an early CVT!] The Dynaflow
used a five element converter to produce the wide range of torque
multiplication [i.e. wide range of drive ratios] needed to propel a
heavy vehicle.
* Acceleration. The load is accelerating but there still is a
relatively large difference between pump and turbine speed. [i.e. low
gear] ...The amount of multiplication will depend upon the actual
difference between pump and turbine speed, [i.e. the effective drive
ratio] as well as various other design factors. [efficiency]
* Coupling. The turbine has reached approximately 90 percent of
the speed of the pump. Torque multiplication has ceased [i.e. gear
ratio is slightly less than 1:1 but the slight power increase from
higher engine rpm is lost to inefficiency] and the torque converter is
behaving in a manner similar to a fluid coupling. In modern automotive
applications, it is usually at this stage of operation where the
lock-up clutch is applied, a procedure that tends to improve fuel
efficiency.
--end quotes--
When they say "torque multiplication" what they really mean is a drive
ratio less than 1:1. IOW, every transmission is a torque multiplier,
at least in the lower gears.
>
>> The only way to do that is
>> to increase the throttle opening or increase the rpm. The throttle
>> opening is determined by your foot (and it wouldn't be much of a trick
>> for the torque multiplier to be just an extra jerk on the throttle and
>> it wouldn't do much good if the throttle were already wide open.)
>> However, rpm is largely controlled by the transmission. The
>> transmission allows the engine to run a little faster and therefore
>> produce more power which is transmitted to the wheels. This is what I
>> meant by a mini downshift.
>
>that's the lockup clutch releasing.
Right, there is no torque multiplication in the TC unless it is
slipping.
>
>>
>>>> They take high rpm/low torque and turn it into low rpm
>>>> high torque. If it were perfectly efficient, the power output would
>>>> be equal to input but of course it is always less. No way to get more
>>>> power out unless you put more power in, i.e. run the engine at higher
>>>> rpm.
>>> see above.
>>>
>>>>>>> if is however a great
>>>>>>> way of achieving absolute optimum gear for all conditions.
>>>>>> I agree that it has a big theoretical advantage, especially compared
>>>>>> to a conventional AT.
>>>>> compared to /any/ transmission. there are mechanical efficiency issues
>>>>> with the friction interface, but that is more than outweighed by ratio
>>>>> flexibility and ability to keep the engine at its most efficient.
>>>> The why doesn't the Versa with a CVT get better mileage or accelerate
>>>> faster than the Versa with an MT? Unfortunately, there are few cars
>>>> which allow you to directly compare CVT vs. MT.
>>> civic hx was significantly more fuel efficient than the stick.
>>
>> I gather that was the CVT-equipped model. They don't sell it anymore.
>> I guess people hated it more than high fuel costs.
>
>my money's on dealer prejudice, not consumer. by the same token, the
>hatchback has been all but dropped in the u.s. afaikt, that's more to
>do with vehicles with the same utility selling for $30k rather than $15k
>for a hatch, not consumer demand. try buying a used hatchback civic
>here in the bay area - good luck! people just keep them - they never
>sell.
I personally like hatchbacks and I know they have a following. I too
am surprised and disappointed that they have all but disappeared. I
don't know I am ready to sign on to the conspiracy theory though. If
there were a strong market, Someone like Mazda or Nissan would jump to
serve it to increase their sales. apparently there isn't enough
demand to justify the high expense of two body styles and the sedan is
more popular.
I suppose I could blame the shortage of MTs on greedy dealers and
manufacturers who want to force me to buy a more expensive AT.
However, I am more inclined to blame Starbucks.
>>>>>>>> A lot of people don't like
>>>>>>>> them at all, but others say they get used to it. (The perception
>>>>>>>> problem is so bad that some manufacturers program virtual gears into
>>>>>>>> them thereby defeating the chief advantage of the CVT.)
>>>>>>> absolutely! i drove a "real" cvt one when i was in europe years ago,
>>>>>>> and yes it is /real/ weird at first. but it's amazing how much you can
>>>>>>> get out of a small 2-cylinder engine when it's got perfect gearing.
>>>>>>> quite fun! this particular model had 2 independent drives too, so not
>>>>>>> only did you have optimum gearing, you had limited slip diff benefits in
>>>>>>> snow & ice too.
>>>>>>> http://www.ritzsite.demon.nl/DAF/DAF_cars_p2.htm
>>>>>> That was the original CVT. Do you remember who offered the first CVT
>>>>>> in the US. (I don't think they ever sold the Daffodil here.)
>>>>> subaru?
>>>> That is what I recall. The car was called the Justy.
>>>>
>>>>>>>> I only rode
>>>>>>>> in one CVT car, a Nissan luxury sedan in Japan and it wasn't bad in
>>>>>>>> that application. He drove it fairly aggressively too - we hit almost
>>>>>>>> 180 kph on the expressway. I would like to try one of these. I don't
>>>>>>>> know if I would like it or not.
>>>>>>> if you're not used to traditional automatics, the transition is easy.
>>>>>>> if you're used to traditional autos, its weird for a few minutes because
>>>>>>> it doesn't "shift", but beyond that, they're actually very impressive.
>>>>>> Again though, I am not sure they are any faster or more efficient than
>>>>>> a good MT.
>>>>> well, the daf was only 650cc iirc, and 0-30, that wasn't much to touch it.
>>>> I think the Honda 600 would have blown its petals off. ;-)
>>>>
>>>>>> Consumer Reports tested the Versa with MT and with CVT.
>>>>>> The MT version was 0.6 seconds faster to 60 and got one more mpg. (And
>>>>>> CR panned that MT.) They also tested MT and (conventional) AT
>>>>>> versions of Fit, Rio, Accent and Yaris. In each case the MT was 2 - 3
>>>>>> seconds faster and got 2 more mpg, so the CVT was clearly better than
>>>>>> an AT but not as good as even a mediocre MT, at last on raw numbers.
>>>>> that depends on the management system. the modern cvt's "simulate" gear
>>>>> shifts which is the dumbest damned thing since it's not utilizing the
>>>>> inherent benefit of the system! on that basis, i'm not surprised.
>>>> Does the Versa do that? CR didn't mention it.
>>> don't know. given "consumer demand", i expect so.
>>
>> Like I said, they hate it just like you think I would. (Actually I
>> would love to try one, I do think it is a neat idea and it would be
>> fun for a while at least. Only after the novelty wore off could I
>> tell you if I like it or hate it. I actually suspect that I would
>> like it more than a conventional AT.)
>>
>> Here is an interesting review I found. (It indicates that the Versa
>> CVT does not have "gears," so the fact that it was slower and less
>> fuel efficient than the "clunky" MT is significant.) I made one
>> editorial comment in brackets.
>>
>> --quote--
>> But the CVT is the one that shines. Its proprietary design, benefiting
>> from Nissan's global cooperation with French carmaker Renault, is
>> uncanny in the way it maintains optimal engine rpm within the most
>> fuel-efficient torque range. It senses, for example, when the Versa is
>> proceeding downhill and glides effortlessly into a lower gear range to
>> slow the car with engine braking. [What if you don't want engine
>> braking? It is wasting kinetic energy = fuel.
>
>not correct. when engine braking, fuel delivery is completely stopped.
But kinetic energy is being lost. Doesn't matter if the car has to be
brought to a stop anyway, but if the driving situation requires little
or no compression braking and the computer orders a lot, the car will
slow unnecessarily and fuel will be consumed bringing it back up to
speed.
I use compression braking a lot. Sometimes I use a little, sometimes
I use a lot. Sometimes I coast with the clutch disengaged for maximum
distance. A transmission that always applies medium compression
braking is not as going to achieve the same thing.
>> What it needs in a
>> powerful computer with optical sensors to look ahead, evaluate the
>> situation and decide whether engine braking is advantageous
>
>why? i don't want my car making /that/ kind of decision. seriously,
But you are satisfied with it making the decision mindlessly. I agree
I do not want the car making that decision. I want to make it myself
and shift the transmission accordingly. My brain is the powerful
computer and my eyes are the optical sensors.
>auto engine braking only happens when you're foot braking - just like on
>a stick.
Not true. I use compression braking all the time with my foot off the
brake. Descending grades would be a prime example except that I live
in Chicago and there are no hills. Instead, I am the only guy in
crawling rush hour traffic not flashing his brake lights every 20
feet. It is way more fun than an AT if you play the game.
>you can't criticize what you've not used dude.
I am only pointing out that this feature has a down side. It might
not bother 95% of drivers, but it would bother me.
>
>>.]
>> Conversely, under pedal-to-the-floor acceleration, the CVT instantly
>> launches the engine to its max-torque rpm, then keeps it there
>> unchanged until a desired highway speed is reached.
>>
>> This goes against every traditional sensation of driving, wherein gear
>> changes trigger a momentary drop in rpm as the higher gear ratio is
>> engaged. There's a lot of mechanical inefficiency in that traditional
>> gear-change syncopation; and Versa's CVT eliminates it. When first
>> experiencing the CVT's behavior, it feels wrong, sounds noisy. In
>> truth, however, it's mostly the lack of noticeable gear changes that's
>> merely thwarting a driver's subconscious expectation of rising-falling
>> rpms as gears change.
>> --end quote--
>>
>> http://www.carlist.com/newcars/2007/ncr1116.html
>>
>>
>>>>>> And yet, there is hardly a proliferation of CVTs on the market. Most
>>>>>> of them seem to be on hybrids in fact.
>>>>> that's consumer and mechanic inertia - nothing to do with benefits or
>>>>> reliability. trust me on that one - i've driven the daf for an extended
>>>>> period and it's a great system.
>>>> Maybe. I would gladly trade the AT in my Ody for one if it was proven
>>>> reliable. Not all are. The on in the Saturn Vue was a disaster, but
>>>> I guess you have to expect that from GM. The Japanese units don't
>>>> seem to have any problems.
>>> i've never heard of problems with the civic hx.
>>
>> Neither have I, but then there aren't a lot out there.
>
>/all/ the 96-2000 hx autos are cvt.
Yes, but how many is that? If they had sold that many, it would still
be on the market. Don't get me wrong, I don't think they are any less
reliable than a conventional Civic AT, but I don't think there are
enough out there to really know for sure. They certainly aren't
terrible like the GM CVT.
01-13-2007 | 12:34 PM
#98
Guest
Posts: n/a
Re: Transmission Activity
Gordon McGrew wrote:
<snip>
>
> I use compression braking a lot. Sometimes I use a little, sometimes
> I use a lot. Sometimes I coast with the clutch disengaged for maximum
> distance.
that's unsafe btw.
> A transmission that always applies medium compression
> braking is not as going to achieve the same thing.
>
>>> What it needs in a
>>> powerful computer with optical sensors to look ahead, evaluate the
>>> situation and decide whether engine braking is advantageous
>> why? i don't want my car making /that/ kind of decision. seriously,
>
> But you are satisfied with it making the decision mindlessly.
no i'm not. i am satisfied from extensive experience over many years in
all conditions and many many miles, clearly based on extensive research
on driver usage and testing of driveability, that programmed engine
braking algorithms used in electronically controlled automatics are
highly proficient and effective. as you would know if you'd driven one.
> I agree
> I do not want the car making that decision.
i don't want it making an independent decision. they're programed to
make *dependent* decisions based on how the driver is asking the vehicle
to behave. which is what you want.
> I want to make it myself
> and shift the transmission accordingly.
you can - use the shift lever.
> My brain is the powerful
> computer and my eyes are the optical sensors.
but the two are apparently unable to work together to get the *** on
into a dealer to test out the new fangled machine the mouth is criticizing.
>
>> auto engine braking only happens when you're foot braking - just like on
>> a stick.
>
> Not true. I use compression braking all the time with my foot off the
> brake.
no, it's true. autos engine brake, just like a stick. and you can
engine brake without the foot brake too. we've discussed that repeatedly.
> Descending grades would be a prime example except that I live
> in Chicago and there are no hills. Instead, I am the only guy in
> crawling rush hour traffic not flashing his brake lights every 20
> feet. It is way more fun than an AT if you play the game.
see above.
>
>> you can't criticize what you've not used dude.
>
> I am only pointing out that this feature has a down side. It might
> not bother 95% of drivers, but it would bother me.
but your assessment of the whole situation is flawed - it's assumption
and speculation /not/ based on either experience or sufficient
knowledge. modern autos shift to engine brake. they do it flawlessly
and just as a normal driver would shift a stick. and the degree of
braking depends on how hard the driver's braking - /that/ is /more/
sophisticated than the average stick driver.
<snip>
>
> I use compression braking a lot. Sometimes I use a little, sometimes
> I use a lot. Sometimes I coast with the clutch disengaged for maximum
> distance.
that's unsafe btw.
> A transmission that always applies medium compression
> braking is not as going to achieve the same thing.
>
>>> What it needs in a
>>> powerful computer with optical sensors to look ahead, evaluate the
>>> situation and decide whether engine braking is advantageous
>> why? i don't want my car making /that/ kind of decision. seriously,
>
> But you are satisfied with it making the decision mindlessly.
no i'm not. i am satisfied from extensive experience over many years in
all conditions and many many miles, clearly based on extensive research
on driver usage and testing of driveability, that programmed engine
braking algorithms used in electronically controlled automatics are
highly proficient and effective. as you would know if you'd driven one.
> I agree
> I do not want the car making that decision.
i don't want it making an independent decision. they're programed to
make *dependent* decisions based on how the driver is asking the vehicle
to behave. which is what you want.
> I want to make it myself
> and shift the transmission accordingly.
you can - use the shift lever.
> My brain is the powerful
> computer and my eyes are the optical sensors.
but the two are apparently unable to work together to get the *** on
into a dealer to test out the new fangled machine the mouth is criticizing.
>
>> auto engine braking only happens when you're foot braking - just like on
>> a stick.
>
> Not true. I use compression braking all the time with my foot off the
> brake.
no, it's true. autos engine brake, just like a stick. and you can
engine brake without the foot brake too. we've discussed that repeatedly.
> Descending grades would be a prime example except that I live
> in Chicago and there are no hills. Instead, I am the only guy in
> crawling rush hour traffic not flashing his brake lights every 20
> feet. It is way more fun than an AT if you play the game.
see above.
>
>> you can't criticize what you've not used dude.
>
> I am only pointing out that this feature has a down side. It might
> not bother 95% of drivers, but it would bother me.
but your assessment of the whole situation is flawed - it's assumption
and speculation /not/ based on either experience or sufficient
knowledge. modern autos shift to engine brake. they do it flawlessly
and just as a normal driver would shift a stick. and the degree of
braking depends on how hard the driver's braking - /that/ is /more/
sophisticated than the average stick driver.
01-13-2007 | 12:34 PM
#99
Guest
Posts: n/a
Re: Transmission Activity
Gordon McGrew wrote:
<snip>
>
> I use compression braking a lot. Sometimes I use a little, sometimes
> I use a lot. Sometimes I coast with the clutch disengaged for maximum
> distance.
that's unsafe btw.
> A transmission that always applies medium compression
> braking is not as going to achieve the same thing.
>
>>> What it needs in a
>>> powerful computer with optical sensors to look ahead, evaluate the
>>> situation and decide whether engine braking is advantageous
>> why? i don't want my car making /that/ kind of decision. seriously,
>
> But you are satisfied with it making the decision mindlessly.
no i'm not. i am satisfied from extensive experience over many years in
all conditions and many many miles, clearly based on extensive research
on driver usage and testing of driveability, that programmed engine
braking algorithms used in electronically controlled automatics are
highly proficient and effective. as you would know if you'd driven one.
> I agree
> I do not want the car making that decision.
i don't want it making an independent decision. they're programed to
make *dependent* decisions based on how the driver is asking the vehicle
to behave. which is what you want.
> I want to make it myself
> and shift the transmission accordingly.
you can - use the shift lever.
> My brain is the powerful
> computer and my eyes are the optical sensors.
but the two are apparently unable to work together to get the *** on
into a dealer to test out the new fangled machine the mouth is criticizing.
>
>> auto engine braking only happens when you're foot braking - just like on
>> a stick.
>
> Not true. I use compression braking all the time with my foot off the
> brake.
no, it's true. autos engine brake, just like a stick. and you can
engine brake without the foot brake too. we've discussed that repeatedly.
> Descending grades would be a prime example except that I live
> in Chicago and there are no hills. Instead, I am the only guy in
> crawling rush hour traffic not flashing his brake lights every 20
> feet. It is way more fun than an AT if you play the game.
see above.
>
>> you can't criticize what you've not used dude.
>
> I am only pointing out that this feature has a down side. It might
> not bother 95% of drivers, but it would bother me.
but your assessment of the whole situation is flawed - it's assumption
and speculation /not/ based on either experience or sufficient
knowledge. modern autos shift to engine brake. they do it flawlessly
and just as a normal driver would shift a stick. and the degree of
braking depends on how hard the driver's braking - /that/ is /more/
sophisticated than the average stick driver.
<snip>
>
> I use compression braking a lot. Sometimes I use a little, sometimes
> I use a lot. Sometimes I coast with the clutch disengaged for maximum
> distance.
that's unsafe btw.
> A transmission that always applies medium compression
> braking is not as going to achieve the same thing.
>
>>> What it needs in a
>>> powerful computer with optical sensors to look ahead, evaluate the
>>> situation and decide whether engine braking is advantageous
>> why? i don't want my car making /that/ kind of decision. seriously,
>
> But you are satisfied with it making the decision mindlessly.
no i'm not. i am satisfied from extensive experience over many years in
all conditions and many many miles, clearly based on extensive research
on driver usage and testing of driveability, that programmed engine
braking algorithms used in electronically controlled automatics are
highly proficient and effective. as you would know if you'd driven one.
> I agree
> I do not want the car making that decision.
i don't want it making an independent decision. they're programed to
make *dependent* decisions based on how the driver is asking the vehicle
to behave. which is what you want.
> I want to make it myself
> and shift the transmission accordingly.
you can - use the shift lever.
> My brain is the powerful
> computer and my eyes are the optical sensors.
but the two are apparently unable to work together to get the *** on
into a dealer to test out the new fangled machine the mouth is criticizing.
>
>> auto engine braking only happens when you're foot braking - just like on
>> a stick.
>
> Not true. I use compression braking all the time with my foot off the
> brake.
no, it's true. autos engine brake, just like a stick. and you can
engine brake without the foot brake too. we've discussed that repeatedly.
> Descending grades would be a prime example except that I live
> in Chicago and there are no hills. Instead, I am the only guy in
> crawling rush hour traffic not flashing his brake lights every 20
> feet. It is way more fun than an AT if you play the game.
see above.
>
>> you can't criticize what you've not used dude.
>
> I am only pointing out that this feature has a down side. It might
> not bother 95% of drivers, but it would bother me.
but your assessment of the whole situation is flawed - it's assumption
and speculation /not/ based on either experience or sufficient
knowledge. modern autos shift to engine brake. they do it flawlessly
and just as a normal driver would shift a stick. and the degree of
braking depends on how hard the driver's braking - /that/ is /more/
sophisticated than the average stick driver.
01-13-2007 | 12:34 PM
#100
Guest
Posts: n/a
Re: Transmission Activity
Gordon McGrew wrote:
<snip>
>
> I use compression braking a lot. Sometimes I use a little, sometimes
> I use a lot. Sometimes I coast with the clutch disengaged for maximum
> distance.
that's unsafe btw.
> A transmission that always applies medium compression
> braking is not as going to achieve the same thing.
>
>>> What it needs in a
>>> powerful computer with optical sensors to look ahead, evaluate the
>>> situation and decide whether engine braking is advantageous
>> why? i don't want my car making /that/ kind of decision. seriously,
>
> But you are satisfied with it making the decision mindlessly.
no i'm not. i am satisfied from extensive experience over many years in
all conditions and many many miles, clearly based on extensive research
on driver usage and testing of driveability, that programmed engine
braking algorithms used in electronically controlled automatics are
highly proficient and effective. as you would know if you'd driven one.
> I agree
> I do not want the car making that decision.
i don't want it making an independent decision. they're programed to
make *dependent* decisions based on how the driver is asking the vehicle
to behave. which is what you want.
> I want to make it myself
> and shift the transmission accordingly.
you can - use the shift lever.
> My brain is the powerful
> computer and my eyes are the optical sensors.
but the two are apparently unable to work together to get the *** on
into a dealer to test out the new fangled machine the mouth is criticizing.
>
>> auto engine braking only happens when you're foot braking - just like on
>> a stick.
>
> Not true. I use compression braking all the time with my foot off the
> brake.
no, it's true. autos engine brake, just like a stick. and you can
engine brake without the foot brake too. we've discussed that repeatedly.
> Descending grades would be a prime example except that I live
> in Chicago and there are no hills. Instead, I am the only guy in
> crawling rush hour traffic not flashing his brake lights every 20
> feet. It is way more fun than an AT if you play the game.
see above.
>
>> you can't criticize what you've not used dude.
>
> I am only pointing out that this feature has a down side. It might
> not bother 95% of drivers, but it would bother me.
but your assessment of the whole situation is flawed - it's assumption
and speculation /not/ based on either experience or sufficient
knowledge. modern autos shift to engine brake. they do it flawlessly
and just as a normal driver would shift a stick. and the degree of
braking depends on how hard the driver's braking - /that/ is /more/
sophisticated than the average stick driver.
<snip>
>
> I use compression braking a lot. Sometimes I use a little, sometimes
> I use a lot. Sometimes I coast with the clutch disengaged for maximum
> distance.
that's unsafe btw.
> A transmission that always applies medium compression
> braking is not as going to achieve the same thing.
>
>>> What it needs in a
>>> powerful computer with optical sensors to look ahead, evaluate the
>>> situation and decide whether engine braking is advantageous
>> why? i don't want my car making /that/ kind of decision. seriously,
>
> But you are satisfied with it making the decision mindlessly.
no i'm not. i am satisfied from extensive experience over many years in
all conditions and many many miles, clearly based on extensive research
on driver usage and testing of driveability, that programmed engine
braking algorithms used in electronically controlled automatics are
highly proficient and effective. as you would know if you'd driven one.
> I agree
> I do not want the car making that decision.
i don't want it making an independent decision. they're programed to
make *dependent* decisions based on how the driver is asking the vehicle
to behave. which is what you want.
> I want to make it myself
> and shift the transmission accordingly.
you can - use the shift lever.
> My brain is the powerful
> computer and my eyes are the optical sensors.
but the two are apparently unable to work together to get the *** on
into a dealer to test out the new fangled machine the mouth is criticizing.
>
>> auto engine braking only happens when you're foot braking - just like on
>> a stick.
>
> Not true. I use compression braking all the time with my foot off the
> brake.
no, it's true. autos engine brake, just like a stick. and you can
engine brake without the foot brake too. we've discussed that repeatedly.
> Descending grades would be a prime example except that I live
> in Chicago and there are no hills. Instead, I am the only guy in
> crawling rush hour traffic not flashing his brake lights every 20
> feet. It is way more fun than an AT if you play the game.
see above.
>
>> you can't criticize what you've not used dude.
>
> I am only pointing out that this feature has a down side. It might
> not bother 95% of drivers, but it would bother me.
but your assessment of the whole situation is flawed - it's assumption
and speculation /not/ based on either experience or sufficient
knowledge. modern autos shift to engine brake. they do it flawlessly
and just as a normal driver would shift a stick. and the degree of
braking depends on how hard the driver's braking - /that/ is /more/
sophisticated than the average stick driver.
01-13-2007 | 12:34 PM
#101
Guest
Posts: n/a
Re: Transmission Activity
Gordon McGrew wrote:
<snip>
>
> I use compression braking a lot. Sometimes I use a little, sometimes
> I use a lot. Sometimes I coast with the clutch disengaged for maximum
> distance.
that's unsafe btw.
> A transmission that always applies medium compression
> braking is not as going to achieve the same thing.
>
>>> What it needs in a
>>> powerful computer with optical sensors to look ahead, evaluate the
>>> situation and decide whether engine braking is advantageous
>> why? i don't want my car making /that/ kind of decision. seriously,
>
> But you are satisfied with it making the decision mindlessly.
no i'm not. i am satisfied from extensive experience over many years in
all conditions and many many miles, clearly based on extensive research
on driver usage and testing of driveability, that programmed engine
braking algorithms used in electronically controlled automatics are
highly proficient and effective. as you would know if you'd driven one.
> I agree
> I do not want the car making that decision.
i don't want it making an independent decision. they're programed to
make *dependent* decisions based on how the driver is asking the vehicle
to behave. which is what you want.
> I want to make it myself
> and shift the transmission accordingly.
you can - use the shift lever.
> My brain is the powerful
> computer and my eyes are the optical sensors.
but the two are apparently unable to work together to get the *** on
into a dealer to test out the new fangled machine the mouth is criticizing.
>
>> auto engine braking only happens when you're foot braking - just like on
>> a stick.
>
> Not true. I use compression braking all the time with my foot off the
> brake.
no, it's true. autos engine brake, just like a stick. and you can
engine brake without the foot brake too. we've discussed that repeatedly.
> Descending grades would be a prime example except that I live
> in Chicago and there are no hills. Instead, I am the only guy in
> crawling rush hour traffic not flashing his brake lights every 20
> feet. It is way more fun than an AT if you play the game.
see above.
>
>> you can't criticize what you've not used dude.
>
> I am only pointing out that this feature has a down side. It might
> not bother 95% of drivers, but it would bother me.
but your assessment of the whole situation is flawed - it's assumption
and speculation /not/ based on either experience or sufficient
knowledge. modern autos shift to engine brake. they do it flawlessly
and just as a normal driver would shift a stick. and the degree of
braking depends on how hard the driver's braking - /that/ is /more/
sophisticated than the average stick driver.
<snip>
>
> I use compression braking a lot. Sometimes I use a little, sometimes
> I use a lot. Sometimes I coast with the clutch disengaged for maximum
> distance.
that's unsafe btw.
> A transmission that always applies medium compression
> braking is not as going to achieve the same thing.
>
>>> What it needs in a
>>> powerful computer with optical sensors to look ahead, evaluate the
>>> situation and decide whether engine braking is advantageous
>> why? i don't want my car making /that/ kind of decision. seriously,
>
> But you are satisfied with it making the decision mindlessly.
no i'm not. i am satisfied from extensive experience over many years in
all conditions and many many miles, clearly based on extensive research
on driver usage and testing of driveability, that programmed engine
braking algorithms used in electronically controlled automatics are
highly proficient and effective. as you would know if you'd driven one.
> I agree
> I do not want the car making that decision.
i don't want it making an independent decision. they're programed to
make *dependent* decisions based on how the driver is asking the vehicle
to behave. which is what you want.
> I want to make it myself
> and shift the transmission accordingly.
you can - use the shift lever.
> My brain is the powerful
> computer and my eyes are the optical sensors.
but the two are apparently unable to work together to get the *** on
into a dealer to test out the new fangled machine the mouth is criticizing.
>
>> auto engine braking only happens when you're foot braking - just like on
>> a stick.
>
> Not true. I use compression braking all the time with my foot off the
> brake.
no, it's true. autos engine brake, just like a stick. and you can
engine brake without the foot brake too. we've discussed that repeatedly.
> Descending grades would be a prime example except that I live
> in Chicago and there are no hills. Instead, I am the only guy in
> crawling rush hour traffic not flashing his brake lights every 20
> feet. It is way more fun than an AT if you play the game.
see above.
>
>> you can't criticize what you've not used dude.
>
> I am only pointing out that this feature has a down side. It might
> not bother 95% of drivers, but it would bother me.
but your assessment of the whole situation is flawed - it's assumption
and speculation /not/ based on either experience or sufficient
knowledge. modern autos shift to engine brake. they do it flawlessly
and just as a normal driver would shift a stick. and the degree of
braking depends on how hard the driver's braking - /that/ is /more/
sophisticated than the average stick driver.
01-14-2007 | 01:44 AM
#102
Guest
Posts: n/a
Re: Transmission Activity
On Sat, 13 Jan 2007 09:34:29 -0800, jim beam
<spamvortex@bad.example.net> wrote:
>Gordon McGrew wrote:
><snip>
>>
>> I use compression braking a lot. Sometimes I use a little, sometimes
>> I use a lot. Sometimes I coast with the clutch disengaged for maximum
>> distance.
>
>that's unsafe btw.
Why?
>> A transmission that always applies medium compression
>> braking is not as going to achieve the same thing.
>>
>>>> What it needs in a
>>>> powerful computer with optical sensors to look ahead, evaluate the
>>>> situation and decide whether engine braking is advantageous
>>> why? i don't want my car making /that/ kind of decision. seriously,
>>
>> But you are satisfied with it making the decision mindlessly.
>
>no i'm not. i am satisfied from extensive experience over many years in
>all conditions and many many miles, clearly based on extensive research
>on driver usage and testing of driveability, that programmed engine
>braking algorithms used in electronically controlled automatics are
>highly proficient and effective. as you would know if you'd driven one.
It can have all the algorithms it wants but it doesn't know whether
the hill is long or short. It doesn't know whether, at the bottom of
the hill, there will be the beginning of a steep ascent or a freight
train crossing. It just goes for some predetermined drive ratio,
oblivious to what is outside the window. I chose the level of
compression braking based on information the computer just doesn't
have.
>> I agree
>> I do not want the car making that decision.
>
>i don't want it making an independent decision. they're programed to
>make *dependent* decisions based on how the driver is asking the vehicle
>to behave. which is what you want.
No, I want to tell it what to do. I don't want it to infer what I
might want the transmission to do based on what I am doing with the
throttle and brake. At least a conventional AT gives you some direct
control over this. I would like to believe that the CVT does also,
but I don't really know. It should assume that I want minimal
compression braking unless I specifically signal otherwise. If it
wants to assume I want more compression braking if I am at least
moderately on the service brake, that is OK. But if I take my foot
off the brake, it should resume minimum compression.
>> I want to make it myself
>> and shift the transmission accordingly.
>
>you can - use the shift lever.
Not clear on how you control the CVT, but the article implied that it
automatically went to some medium level of compression braking. It
wasn't clear that you could over-ride this and force less or more
compression braking.
>> My brain is the powerful
>> computer and my eyes are the optical sensors.
>
>but the two are apparently unable to work together to get the *** on
>into a dealer to test out the new fangled machine the mouth is criticizing.
That's just it. I don't test drive cars unless I am considering
buying one. If I get the opportunity, I would gladly take it. But I
don't think I would ever consider buying one if an MT were an option.
>>> auto engine braking only happens when you're foot braking - just like on
>>> a stick.
>>
>> Not true. I use compression braking all the time with my foot off the
>> brake.
>
>no, it's true. autos engine brake, just like a stick. and you can
>engine brake without the foot brake too. we've discussed that repeatedly.
But you said it happens *only* when you are foot braking. I thought
you were referring to the CVT. I know how a conventional AT works.
>
>> Descending grades would be a prime example except that I live
>> in Chicago and there are no hills. Instead, I am the only guy in
>> crawling rush hour traffic not flashing his brake lights every 20
>> feet. It is way more fun than an AT if you play the game.
>
>see above.
>
>>
>>> you can't criticize what you've not used dude.
>>
>> I am only pointing out that this feature has a down side. It might
>> not bother 95% of drivers, but it would bother me.
>
>but your assessment of the whole situation is flawed - it's assumption
>and speculation /not/ based on either experience or sufficient
>knowledge. modern autos shift to engine brake. they do it flawlessly
>and just as a normal driver would shift a stick. and the degree of
>braking depends on how hard the driver's braking - /that/ is /more/
>sophisticated than the average stick driver.
It may or may not be more sophisticated than the *average* stick
driver but it is no way more sophisticated than what *I* do. I can't
decide what gear to be in without assessing the situation outside the
windshield. No matter how powerful the computer and elegant the
software, it is a blind driver. I use engine braking instead of the
service brake. To have it mindlessly aping what I do with the service
brake is hardly sophisticated.
<spamvortex@bad.example.net> wrote:
>Gordon McGrew wrote:
><snip>
>>
>> I use compression braking a lot. Sometimes I use a little, sometimes
>> I use a lot. Sometimes I coast with the clutch disengaged for maximum
>> distance.
>
>that's unsafe btw.
Why?
>> A transmission that always applies medium compression
>> braking is not as going to achieve the same thing.
>>
>>>> What it needs in a
>>>> powerful computer with optical sensors to look ahead, evaluate the
>>>> situation and decide whether engine braking is advantageous
>>> why? i don't want my car making /that/ kind of decision. seriously,
>>
>> But you are satisfied with it making the decision mindlessly.
>
>no i'm not. i am satisfied from extensive experience over many years in
>all conditions and many many miles, clearly based on extensive research
>on driver usage and testing of driveability, that programmed engine
>braking algorithms used in electronically controlled automatics are
>highly proficient and effective. as you would know if you'd driven one.
It can have all the algorithms it wants but it doesn't know whether
the hill is long or short. It doesn't know whether, at the bottom of
the hill, there will be the beginning of a steep ascent or a freight
train crossing. It just goes for some predetermined drive ratio,
oblivious to what is outside the window. I chose the level of
compression braking based on information the computer just doesn't
have.
>> I agree
>> I do not want the car making that decision.
>
>i don't want it making an independent decision. they're programed to
>make *dependent* decisions based on how the driver is asking the vehicle
>to behave. which is what you want.
No, I want to tell it what to do. I don't want it to infer what I
might want the transmission to do based on what I am doing with the
throttle and brake. At least a conventional AT gives you some direct
control over this. I would like to believe that the CVT does also,
but I don't really know. It should assume that I want minimal
compression braking unless I specifically signal otherwise. If it
wants to assume I want more compression braking if I am at least
moderately on the service brake, that is OK. But if I take my foot
off the brake, it should resume minimum compression.
>> I want to make it myself
>> and shift the transmission accordingly.
>
>you can - use the shift lever.
Not clear on how you control the CVT, but the article implied that it
automatically went to some medium level of compression braking. It
wasn't clear that you could over-ride this and force less or more
compression braking.
>> My brain is the powerful
>> computer and my eyes are the optical sensors.
>
>but the two are apparently unable to work together to get the *** on
>into a dealer to test out the new fangled machine the mouth is criticizing.
That's just it. I don't test drive cars unless I am considering
buying one. If I get the opportunity, I would gladly take it. But I
don't think I would ever consider buying one if an MT were an option.
>>> auto engine braking only happens when you're foot braking - just like on
>>> a stick.
>>
>> Not true. I use compression braking all the time with my foot off the
>> brake.
>
>no, it's true. autos engine brake, just like a stick. and you can
>engine brake without the foot brake too. we've discussed that repeatedly.
But you said it happens *only* when you are foot braking. I thought
you were referring to the CVT. I know how a conventional AT works.
>
>> Descending grades would be a prime example except that I live
>> in Chicago and there are no hills. Instead, I am the only guy in
>> crawling rush hour traffic not flashing his brake lights every 20
>> feet. It is way more fun than an AT if you play the game.
>
>see above.
>
>>
>>> you can't criticize what you've not used dude.
>>
>> I am only pointing out that this feature has a down side. It might
>> not bother 95% of drivers, but it would bother me.
>
>but your assessment of the whole situation is flawed - it's assumption
>and speculation /not/ based on either experience or sufficient
>knowledge. modern autos shift to engine brake. they do it flawlessly
>and just as a normal driver would shift a stick. and the degree of
>braking depends on how hard the driver's braking - /that/ is /more/
>sophisticated than the average stick driver.
It may or may not be more sophisticated than the *average* stick
driver but it is no way more sophisticated than what *I* do. I can't
decide what gear to be in without assessing the situation outside the
windshield. No matter how powerful the computer and elegant the
software, it is a blind driver. I use engine braking instead of the
service brake. To have it mindlessly aping what I do with the service
brake is hardly sophisticated.
01-14-2007 | 01:44 AM
#103
Guest
Posts: n/a
Re: Transmission Activity
On Sat, 13 Jan 2007 09:34:29 -0800, jim beam
<spamvortex@bad.example.net> wrote:
>Gordon McGrew wrote:
><snip>
>>
>> I use compression braking a lot. Sometimes I use a little, sometimes
>> I use a lot. Sometimes I coast with the clutch disengaged for maximum
>> distance.
>
>that's unsafe btw.
Why?
>> A transmission that always applies medium compression
>> braking is not as going to achieve the same thing.
>>
>>>> What it needs in a
>>>> powerful computer with optical sensors to look ahead, evaluate the
>>>> situation and decide whether engine braking is advantageous
>>> why? i don't want my car making /that/ kind of decision. seriously,
>>
>> But you are satisfied with it making the decision mindlessly.
>
>no i'm not. i am satisfied from extensive experience over many years in
>all conditions and many many miles, clearly based on extensive research
>on driver usage and testing of driveability, that programmed engine
>braking algorithms used in electronically controlled automatics are
>highly proficient and effective. as you would know if you'd driven one.
It can have all the algorithms it wants but it doesn't know whether
the hill is long or short. It doesn't know whether, at the bottom of
the hill, there will be the beginning of a steep ascent or a freight
train crossing. It just goes for some predetermined drive ratio,
oblivious to what is outside the window. I chose the level of
compression braking based on information the computer just doesn't
have.
>> I agree
>> I do not want the car making that decision.
>
>i don't want it making an independent decision. they're programed to
>make *dependent* decisions based on how the driver is asking the vehicle
>to behave. which is what you want.
No, I want to tell it what to do. I don't want it to infer what I
might want the transmission to do based on what I am doing with the
throttle and brake. At least a conventional AT gives you some direct
control over this. I would like to believe that the CVT does also,
but I don't really know. It should assume that I want minimal
compression braking unless I specifically signal otherwise. If it
wants to assume I want more compression braking if I am at least
moderately on the service brake, that is OK. But if I take my foot
off the brake, it should resume minimum compression.
>> I want to make it myself
>> and shift the transmission accordingly.
>
>you can - use the shift lever.
Not clear on how you control the CVT, but the article implied that it
automatically went to some medium level of compression braking. It
wasn't clear that you could over-ride this and force less or more
compression braking.
>> My brain is the powerful
>> computer and my eyes are the optical sensors.
>
>but the two are apparently unable to work together to get the *** on
>into a dealer to test out the new fangled machine the mouth is criticizing.
That's just it. I don't test drive cars unless I am considering
buying one. If I get the opportunity, I would gladly take it. But I
don't think I would ever consider buying one if an MT were an option.
>>> auto engine braking only happens when you're foot braking - just like on
>>> a stick.
>>
>> Not true. I use compression braking all the time with my foot off the
>> brake.
>
>no, it's true. autos engine brake, just like a stick. and you can
>engine brake without the foot brake too. we've discussed that repeatedly.
But you said it happens *only* when you are foot braking. I thought
you were referring to the CVT. I know how a conventional AT works.
>
>> Descending grades would be a prime example except that I live
>> in Chicago and there are no hills. Instead, I am the only guy in
>> crawling rush hour traffic not flashing his brake lights every 20
>> feet. It is way more fun than an AT if you play the game.
>
>see above.
>
>>
>>> you can't criticize what you've not used dude.
>>
>> I am only pointing out that this feature has a down side. It might
>> not bother 95% of drivers, but it would bother me.
>
>but your assessment of the whole situation is flawed - it's assumption
>and speculation /not/ based on either experience or sufficient
>knowledge. modern autos shift to engine brake. they do it flawlessly
>and just as a normal driver would shift a stick. and the degree of
>braking depends on how hard the driver's braking - /that/ is /more/
>sophisticated than the average stick driver.
It may or may not be more sophisticated than the *average* stick
driver but it is no way more sophisticated than what *I* do. I can't
decide what gear to be in without assessing the situation outside the
windshield. No matter how powerful the computer and elegant the
software, it is a blind driver. I use engine braking instead of the
service brake. To have it mindlessly aping what I do with the service
brake is hardly sophisticated.
<spamvortex@bad.example.net> wrote:
>Gordon McGrew wrote:
><snip>
>>
>> I use compression braking a lot. Sometimes I use a little, sometimes
>> I use a lot. Sometimes I coast with the clutch disengaged for maximum
>> distance.
>
>that's unsafe btw.
Why?
>> A transmission that always applies medium compression
>> braking is not as going to achieve the same thing.
>>
>>>> What it needs in a
>>>> powerful computer with optical sensors to look ahead, evaluate the
>>>> situation and decide whether engine braking is advantageous
>>> why? i don't want my car making /that/ kind of decision. seriously,
>>
>> But you are satisfied with it making the decision mindlessly.
>
>no i'm not. i am satisfied from extensive experience over many years in
>all conditions and many many miles, clearly based on extensive research
>on driver usage and testing of driveability, that programmed engine
>braking algorithms used in electronically controlled automatics are
>highly proficient and effective. as you would know if you'd driven one.
It can have all the algorithms it wants but it doesn't know whether
the hill is long or short. It doesn't know whether, at the bottom of
the hill, there will be the beginning of a steep ascent or a freight
train crossing. It just goes for some predetermined drive ratio,
oblivious to what is outside the window. I chose the level of
compression braking based on information the computer just doesn't
have.
>> I agree
>> I do not want the car making that decision.
>
>i don't want it making an independent decision. they're programed to
>make *dependent* decisions based on how the driver is asking the vehicle
>to behave. which is what you want.
No, I want to tell it what to do. I don't want it to infer what I
might want the transmission to do based on what I am doing with the
throttle and brake. At least a conventional AT gives you some direct
control over this. I would like to believe that the CVT does also,
but I don't really know. It should assume that I want minimal
compression braking unless I specifically signal otherwise. If it
wants to assume I want more compression braking if I am at least
moderately on the service brake, that is OK. But if I take my foot
off the brake, it should resume minimum compression.
>> I want to make it myself
>> and shift the transmission accordingly.
>
>you can - use the shift lever.
Not clear on how you control the CVT, but the article implied that it
automatically went to some medium level of compression braking. It
wasn't clear that you could over-ride this and force less or more
compression braking.
>> My brain is the powerful
>> computer and my eyes are the optical sensors.
>
>but the two are apparently unable to work together to get the *** on
>into a dealer to test out the new fangled machine the mouth is criticizing.
That's just it. I don't test drive cars unless I am considering
buying one. If I get the opportunity, I would gladly take it. But I
don't think I would ever consider buying one if an MT were an option.
>>> auto engine braking only happens when you're foot braking - just like on
>>> a stick.
>>
>> Not true. I use compression braking all the time with my foot off the
>> brake.
>
>no, it's true. autos engine brake, just like a stick. and you can
>engine brake without the foot brake too. we've discussed that repeatedly.
But you said it happens *only* when you are foot braking. I thought
you were referring to the CVT. I know how a conventional AT works.
>
>> Descending grades would be a prime example except that I live
>> in Chicago and there are no hills. Instead, I am the only guy in
>> crawling rush hour traffic not flashing his brake lights every 20
>> feet. It is way more fun than an AT if you play the game.
>
>see above.
>
>>
>>> you can't criticize what you've not used dude.
>>
>> I am only pointing out that this feature has a down side. It might
>> not bother 95% of drivers, but it would bother me.
>
>but your assessment of the whole situation is flawed - it's assumption
>and speculation /not/ based on either experience or sufficient
>knowledge. modern autos shift to engine brake. they do it flawlessly
>and just as a normal driver would shift a stick. and the degree of
>braking depends on how hard the driver's braking - /that/ is /more/
>sophisticated than the average stick driver.
It may or may not be more sophisticated than the *average* stick
driver but it is no way more sophisticated than what *I* do. I can't
decide what gear to be in without assessing the situation outside the
windshield. No matter how powerful the computer and elegant the
software, it is a blind driver. I use engine braking instead of the
service brake. To have it mindlessly aping what I do with the service
brake is hardly sophisticated.
01-14-2007 | 01:44 AM
#104
Guest
Posts: n/a
Re: Transmission Activity
On Sat, 13 Jan 2007 09:34:29 -0800, jim beam
<spamvortex@bad.example.net> wrote:
>Gordon McGrew wrote:
><snip>
>>
>> I use compression braking a lot. Sometimes I use a little, sometimes
>> I use a lot. Sometimes I coast with the clutch disengaged for maximum
>> distance.
>
>that's unsafe btw.
Why?
>> A transmission that always applies medium compression
>> braking is not as going to achieve the same thing.
>>
>>>> What it needs in a
>>>> powerful computer with optical sensors to look ahead, evaluate the
>>>> situation and decide whether engine braking is advantageous
>>> why? i don't want my car making /that/ kind of decision. seriously,
>>
>> But you are satisfied with it making the decision mindlessly.
>
>no i'm not. i am satisfied from extensive experience over many years in
>all conditions and many many miles, clearly based on extensive research
>on driver usage and testing of driveability, that programmed engine
>braking algorithms used in electronically controlled automatics are
>highly proficient and effective. as you would know if you'd driven one.
It can have all the algorithms it wants but it doesn't know whether
the hill is long or short. It doesn't know whether, at the bottom of
the hill, there will be the beginning of a steep ascent or a freight
train crossing. It just goes for some predetermined drive ratio,
oblivious to what is outside the window. I chose the level of
compression braking based on information the computer just doesn't
have.
>> I agree
>> I do not want the car making that decision.
>
>i don't want it making an independent decision. they're programed to
>make *dependent* decisions based on how the driver is asking the vehicle
>to behave. which is what you want.
No, I want to tell it what to do. I don't want it to infer what I
might want the transmission to do based on what I am doing with the
throttle and brake. At least a conventional AT gives you some direct
control over this. I would like to believe that the CVT does also,
but I don't really know. It should assume that I want minimal
compression braking unless I specifically signal otherwise. If it
wants to assume I want more compression braking if I am at least
moderately on the service brake, that is OK. But if I take my foot
off the brake, it should resume minimum compression.
>> I want to make it myself
>> and shift the transmission accordingly.
>
>you can - use the shift lever.
Not clear on how you control the CVT, but the article implied that it
automatically went to some medium level of compression braking. It
wasn't clear that you could over-ride this and force less or more
compression braking.
>> My brain is the powerful
>> computer and my eyes are the optical sensors.
>
>but the two are apparently unable to work together to get the *** on
>into a dealer to test out the new fangled machine the mouth is criticizing.
That's just it. I don't test drive cars unless I am considering
buying one. If I get the opportunity, I would gladly take it. But I
don't think I would ever consider buying one if an MT were an option.
>>> auto engine braking only happens when you're foot braking - just like on
>>> a stick.
>>
>> Not true. I use compression braking all the time with my foot off the
>> brake.
>
>no, it's true. autos engine brake, just like a stick. and you can
>engine brake without the foot brake too. we've discussed that repeatedly.
But you said it happens *only* when you are foot braking. I thought
you were referring to the CVT. I know how a conventional AT works.
>
>> Descending grades would be a prime example except that I live
>> in Chicago and there are no hills. Instead, I am the only guy in
>> crawling rush hour traffic not flashing his brake lights every 20
>> feet. It is way more fun than an AT if you play the game.
>
>see above.
>
>>
>>> you can't criticize what you've not used dude.
>>
>> I am only pointing out that this feature has a down side. It might
>> not bother 95% of drivers, but it would bother me.
>
>but your assessment of the whole situation is flawed - it's assumption
>and speculation /not/ based on either experience or sufficient
>knowledge. modern autos shift to engine brake. they do it flawlessly
>and just as a normal driver would shift a stick. and the degree of
>braking depends on how hard the driver's braking - /that/ is /more/
>sophisticated than the average stick driver.
It may or may not be more sophisticated than the *average* stick
driver but it is no way more sophisticated than what *I* do. I can't
decide what gear to be in without assessing the situation outside the
windshield. No matter how powerful the computer and elegant the
software, it is a blind driver. I use engine braking instead of the
service brake. To have it mindlessly aping what I do with the service
brake is hardly sophisticated.
<spamvortex@bad.example.net> wrote:
>Gordon McGrew wrote:
><snip>
>>
>> I use compression braking a lot. Sometimes I use a little, sometimes
>> I use a lot. Sometimes I coast with the clutch disengaged for maximum
>> distance.
>
>that's unsafe btw.
Why?
>> A transmission that always applies medium compression
>> braking is not as going to achieve the same thing.
>>
>>>> What it needs in a
>>>> powerful computer with optical sensors to look ahead, evaluate the
>>>> situation and decide whether engine braking is advantageous
>>> why? i don't want my car making /that/ kind of decision. seriously,
>>
>> But you are satisfied with it making the decision mindlessly.
>
>no i'm not. i am satisfied from extensive experience over many years in
>all conditions and many many miles, clearly based on extensive research
>on driver usage and testing of driveability, that programmed engine
>braking algorithms used in electronically controlled automatics are
>highly proficient and effective. as you would know if you'd driven one.
It can have all the algorithms it wants but it doesn't know whether
the hill is long or short. It doesn't know whether, at the bottom of
the hill, there will be the beginning of a steep ascent or a freight
train crossing. It just goes for some predetermined drive ratio,
oblivious to what is outside the window. I chose the level of
compression braking based on information the computer just doesn't
have.
>> I agree
>> I do not want the car making that decision.
>
>i don't want it making an independent decision. they're programed to
>make *dependent* decisions based on how the driver is asking the vehicle
>to behave. which is what you want.
No, I want to tell it what to do. I don't want it to infer what I
might want the transmission to do based on what I am doing with the
throttle and brake. At least a conventional AT gives you some direct
control over this. I would like to believe that the CVT does also,
but I don't really know. It should assume that I want minimal
compression braking unless I specifically signal otherwise. If it
wants to assume I want more compression braking if I am at least
moderately on the service brake, that is OK. But if I take my foot
off the brake, it should resume minimum compression.
>> I want to make it myself
>> and shift the transmission accordingly.
>
>you can - use the shift lever.
Not clear on how you control the CVT, but the article implied that it
automatically went to some medium level of compression braking. It
wasn't clear that you could over-ride this and force less or more
compression braking.
>> My brain is the powerful
>> computer and my eyes are the optical sensors.
>
>but the two are apparently unable to work together to get the *** on
>into a dealer to test out the new fangled machine the mouth is criticizing.
That's just it. I don't test drive cars unless I am considering
buying one. If I get the opportunity, I would gladly take it. But I
don't think I would ever consider buying one if an MT were an option.
>>> auto engine braking only happens when you're foot braking - just like on
>>> a stick.
>>
>> Not true. I use compression braking all the time with my foot off the
>> brake.
>
>no, it's true. autos engine brake, just like a stick. and you can
>engine brake without the foot brake too. we've discussed that repeatedly.
But you said it happens *only* when you are foot braking. I thought
you were referring to the CVT. I know how a conventional AT works.
>
>> Descending grades would be a prime example except that I live
>> in Chicago and there are no hills. Instead, I am the only guy in
>> crawling rush hour traffic not flashing his brake lights every 20
>> feet. It is way more fun than an AT if you play the game.
>
>see above.
>
>>
>>> you can't criticize what you've not used dude.
>>
>> I am only pointing out that this feature has a down side. It might
>> not bother 95% of drivers, but it would bother me.
>
>but your assessment of the whole situation is flawed - it's assumption
>and speculation /not/ based on either experience or sufficient
>knowledge. modern autos shift to engine brake. they do it flawlessly
>and just as a normal driver would shift a stick. and the degree of
>braking depends on how hard the driver's braking - /that/ is /more/
>sophisticated than the average stick driver.
It may or may not be more sophisticated than the *average* stick
driver but it is no way more sophisticated than what *I* do. I can't
decide what gear to be in without assessing the situation outside the
windshield. No matter how powerful the computer and elegant the
software, it is a blind driver. I use engine braking instead of the
service brake. To have it mindlessly aping what I do with the service
brake is hardly sophisticated.
01-14-2007 | 01:44 AM
#105
Guest
Posts: n/a
Re: Transmission Activity
On Sat, 13 Jan 2007 09:34:29 -0800, jim beam
<spamvortex@bad.example.net> wrote:
>Gordon McGrew wrote:
><snip>
>>
>> I use compression braking a lot. Sometimes I use a little, sometimes
>> I use a lot. Sometimes I coast with the clutch disengaged for maximum
>> distance.
>
>that's unsafe btw.
Why?
>> A transmission that always applies medium compression
>> braking is not as going to achieve the same thing.
>>
>>>> What it needs in a
>>>> powerful computer with optical sensors to look ahead, evaluate the
>>>> situation and decide whether engine braking is advantageous
>>> why? i don't want my car making /that/ kind of decision. seriously,
>>
>> But you are satisfied with it making the decision mindlessly.
>
>no i'm not. i am satisfied from extensive experience over many years in
>all conditions and many many miles, clearly based on extensive research
>on driver usage and testing of driveability, that programmed engine
>braking algorithms used in electronically controlled automatics are
>highly proficient and effective. as you would know if you'd driven one.
It can have all the algorithms it wants but it doesn't know whether
the hill is long or short. It doesn't know whether, at the bottom of
the hill, there will be the beginning of a steep ascent or a freight
train crossing. It just goes for some predetermined drive ratio,
oblivious to what is outside the window. I chose the level of
compression braking based on information the computer just doesn't
have.
>> I agree
>> I do not want the car making that decision.
>
>i don't want it making an independent decision. they're programed to
>make *dependent* decisions based on how the driver is asking the vehicle
>to behave. which is what you want.
No, I want to tell it what to do. I don't want it to infer what I
might want the transmission to do based on what I am doing with the
throttle and brake. At least a conventional AT gives you some direct
control over this. I would like to believe that the CVT does also,
but I don't really know. It should assume that I want minimal
compression braking unless I specifically signal otherwise. If it
wants to assume I want more compression braking if I am at least
moderately on the service brake, that is OK. But if I take my foot
off the brake, it should resume minimum compression.
>> I want to make it myself
>> and shift the transmission accordingly.
>
>you can - use the shift lever.
Not clear on how you control the CVT, but the article implied that it
automatically went to some medium level of compression braking. It
wasn't clear that you could over-ride this and force less or more
compression braking.
>> My brain is the powerful
>> computer and my eyes are the optical sensors.
>
>but the two are apparently unable to work together to get the *** on
>into a dealer to test out the new fangled machine the mouth is criticizing.
That's just it. I don't test drive cars unless I am considering
buying one. If I get the opportunity, I would gladly take it. But I
don't think I would ever consider buying one if an MT were an option.
>>> auto engine braking only happens when you're foot braking - just like on
>>> a stick.
>>
>> Not true. I use compression braking all the time with my foot off the
>> brake.
>
>no, it's true. autos engine brake, just like a stick. and you can
>engine brake without the foot brake too. we've discussed that repeatedly.
But you said it happens *only* when you are foot braking. I thought
you were referring to the CVT. I know how a conventional AT works.
>
>> Descending grades would be a prime example except that I live
>> in Chicago and there are no hills. Instead, I am the only guy in
>> crawling rush hour traffic not flashing his brake lights every 20
>> feet. It is way more fun than an AT if you play the game.
>
>see above.
>
>>
>>> you can't criticize what you've not used dude.
>>
>> I am only pointing out that this feature has a down side. It might
>> not bother 95% of drivers, but it would bother me.
>
>but your assessment of the whole situation is flawed - it's assumption
>and speculation /not/ based on either experience or sufficient
>knowledge. modern autos shift to engine brake. they do it flawlessly
>and just as a normal driver would shift a stick. and the degree of
>braking depends on how hard the driver's braking - /that/ is /more/
>sophisticated than the average stick driver.
It may or may not be more sophisticated than the *average* stick
driver but it is no way more sophisticated than what *I* do. I can't
decide what gear to be in without assessing the situation outside the
windshield. No matter how powerful the computer and elegant the
software, it is a blind driver. I use engine braking instead of the
service brake. To have it mindlessly aping what I do with the service
brake is hardly sophisticated.
<spamvortex@bad.example.net> wrote:
>Gordon McGrew wrote:
><snip>
>>
>> I use compression braking a lot. Sometimes I use a little, sometimes
>> I use a lot. Sometimes I coast with the clutch disengaged for maximum
>> distance.
>
>that's unsafe btw.
Why?
>> A transmission that always applies medium compression
>> braking is not as going to achieve the same thing.
>>
>>>> What it needs in a
>>>> powerful computer with optical sensors to look ahead, evaluate the
>>>> situation and decide whether engine braking is advantageous
>>> why? i don't want my car making /that/ kind of decision. seriously,
>>
>> But you are satisfied with it making the decision mindlessly.
>
>no i'm not. i am satisfied from extensive experience over many years in
>all conditions and many many miles, clearly based on extensive research
>on driver usage and testing of driveability, that programmed engine
>braking algorithms used in electronically controlled automatics are
>highly proficient and effective. as you would know if you'd driven one.
It can have all the algorithms it wants but it doesn't know whether
the hill is long or short. It doesn't know whether, at the bottom of
the hill, there will be the beginning of a steep ascent or a freight
train crossing. It just goes for some predetermined drive ratio,
oblivious to what is outside the window. I chose the level of
compression braking based on information the computer just doesn't
have.
>> I agree
>> I do not want the car making that decision.
>
>i don't want it making an independent decision. they're programed to
>make *dependent* decisions based on how the driver is asking the vehicle
>to behave. which is what you want.
No, I want to tell it what to do. I don't want it to infer what I
might want the transmission to do based on what I am doing with the
throttle and brake. At least a conventional AT gives you some direct
control over this. I would like to believe that the CVT does also,
but I don't really know. It should assume that I want minimal
compression braking unless I specifically signal otherwise. If it
wants to assume I want more compression braking if I am at least
moderately on the service brake, that is OK. But if I take my foot
off the brake, it should resume minimum compression.
>> I want to make it myself
>> and shift the transmission accordingly.
>
>you can - use the shift lever.
Not clear on how you control the CVT, but the article implied that it
automatically went to some medium level of compression braking. It
wasn't clear that you could over-ride this and force less or more
compression braking.
>> My brain is the powerful
>> computer and my eyes are the optical sensors.
>
>but the two are apparently unable to work together to get the *** on
>into a dealer to test out the new fangled machine the mouth is criticizing.
That's just it. I don't test drive cars unless I am considering
buying one. If I get the opportunity, I would gladly take it. But I
don't think I would ever consider buying one if an MT were an option.
>>> auto engine braking only happens when you're foot braking - just like on
>>> a stick.
>>
>> Not true. I use compression braking all the time with my foot off the
>> brake.
>
>no, it's true. autos engine brake, just like a stick. and you can
>engine brake without the foot brake too. we've discussed that repeatedly.
But you said it happens *only* when you are foot braking. I thought
you were referring to the CVT. I know how a conventional AT works.
>
>> Descending grades would be a prime example except that I live
>> in Chicago and there are no hills. Instead, I am the only guy in
>> crawling rush hour traffic not flashing his brake lights every 20
>> feet. It is way more fun than an AT if you play the game.
>
>see above.
>
>>
>>> you can't criticize what you've not used dude.
>>
>> I am only pointing out that this feature has a down side. It might
>> not bother 95% of drivers, but it would bother me.
>
>but your assessment of the whole situation is flawed - it's assumption
>and speculation /not/ based on either experience or sufficient
>knowledge. modern autos shift to engine brake. they do it flawlessly
>and just as a normal driver would shift a stick. and the degree of
>braking depends on how hard the driver's braking - /that/ is /more/
>sophisticated than the average stick driver.
It may or may not be more sophisticated than the *average* stick
driver but it is no way more sophisticated than what *I* do. I can't
decide what gear to be in without assessing the situation outside the
windshield. No matter how powerful the computer and elegant the
software, it is a blind driver. I use engine braking instead of the
service brake. To have it mindlessly aping what I do with the service
brake is hardly sophisticated.