Hello, INTRO: I'm making this post to offer my observations, assumptions and conclusions on CVTs-Constantly Variable Transmissions. I want comment, correction, questions and experiences from everyone. My interest in these transmissions peaked recently when my sister was shopping for a new car. HISTORY: In the 1970's magazines ran stories on the "stepless transmission". I believe CVTs were put on the back burner because they weren't needed. Any benefit related to the 70's energy crisis diminished as the gas lines vanished. More recent history made it clear that energy was going to be a volatile commodity, with rising prices, forever. WHAT I THINK HAPPENED: The designs for CVTs were revised, I'm guessing, for use with much smaller engines as well as electric motor hybrid applications. They're predisposed to smaller engines. Fitting an early CVT to the Ford FIVE HUNDRED was a huge failure. Ford couldn't keep up with the volume of transmission swaps, I was told. Still today, car companies are coupling CVTs to their off-the-shelf engines. Heck, Honda's conventional transmissions suffered for a long time due to the weakness of their units. The engines got bigger, the cars got heavier and their transmissions were caught in the middle-literally. That is what the legacy of early CVTs will be, I think. OBSERVATIONS AND HEARSAY: 1) One car company refers to their CVT as a 6 speed. While a CVT might be programmed to use, say, 6 predominating ratios; it doesn't sound like the namesake feature of these units is all that important in the first place. Perhaps they're already pushing the feature into obscurity. One has to ask why. 2) When I've accelerated in a CVT equipped vehicle it dropped into its lowest ratio abruptly causing the engine to wind up fast and loudly. With time will the adjustable cones slam to a limit and will the belt follow as it should? 3) An acquaintance with a garage has reported that that his customers feel occasional shuddering caused by the belt not maintaining full or even contact on its pulleys. He has to allay fears involving products he didn't sell. Tell me, when does chattering improve over time? 4) Another mechanic made a great conversational point by saying, "Hey, they only just perfected regular automatics. Now they're fooling around with these things." CONCLUSIONS: 1) I feel CVTs are at the toddler stage. What's so bad about the car industry is that each feature needs development and the several auto companies will access varying outside firms, have access to only some of the better patents and amass different reliability data. Thus, sub-assemblies of the CVT will develop in a herky jerky manner. Remember, even today's improved Hondas have weak torque converters. This is a case where companies have to collude to shorten the consumer's "guinea pig" stage. 2) Gas is still cheap and Americans love to step on the pedal. We love oomph and auto makers are loathe to downsize their products. The bottom line is cheap, spottily engineered CVTs will be overpowered. They'll loosen and/or burn up. CONCLUSIONS: 1) A CVT has fewer parts, is cheaper to build and the industry wants to use it. This industry has a track record of marketing some really bad products so you can't trust them. They appeal to one's feelings not one's needs. And you can fully discount any "business class" claim that advertising educates a consumer. 2) A Subaru salesman said to us, "We've been making a CVT for over 25 years." I'd love to know the details. He didn't have them at the ready. 3) For my money, a car company can install CVTs on fleet vehicles and report what they learn. DISCLAIMER: I'm not a member of the Stepped Transmission Lovers Association or anything like that. Thanks for reading. Kira
Opinions requested on CVTs so far (long)
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The trade off is the complex nature of the new 8 speeds vs the reported troubles of the CVT. You see torque converters everywhere in the construction industry but no CVT dozers that I am aware of.
So what exactly was the point of this thread? Your observations on a constant velocity transmission. What's a constant variable transmission?
My mother has one in a dodge caliber. Personally I think the engine is underpowered,fuel economy is barely 30mpg. My mustangs mileage is only a few mpg less for way more power so it already has a fail. However she has 100000kms on it thus far and no tranny problems yet. Engine ticks and taps however that's Chrysler for ya since it's sounded like that since new.
I like the idea of a constant velocity tranny. I like how it delivers power in this particular application. Especially since it's underpowered to begin with.
Is the tech mastered yet. Heck no. Gm and dodge are still refining the ancient pushrod motor so I assume there is always room for improvement.
Ultimately car makers are in business to make money. If the cvt trannies cost them enough in warantee work then I believe they will phase them out,until then I expect auto makers to kee using them.
My mother has one in a dodge caliber. Personally I think the engine is underpowered,fuel economy is barely 30mpg. My mustangs mileage is only a few mpg less for way more power so it already has a fail. However she has 100000kms on it thus far and no tranny problems yet. Engine ticks and taps however that's Chrysler for ya since it's sounded like that since new.
I like the idea of a constant velocity tranny. I like how it delivers power in this particular application. Especially since it's underpowered to begin with.
Is the tech mastered yet. Heck no. Gm and dodge are still refining the ancient pushrod motor so I assume there is always room for improvement.
Ultimately car makers are in business to make money. If the cvt trannies cost them enough in warantee work then I believe they will phase them out,until then I expect auto makers to kee using them.
Subaru has been using the CVT since the tiny Justy was built in the late '80s or so-the CVT seems like a good idea, but I agree on waiting a couple years to see if the reliability is there.
doesnt cvt mean continuously variable transmission..
the other 2 dont make sense.
also kira I gave up after about 3 sentences that brick of text is very hard to read.
while it may have looked ok on your screen here is how it looks with my screen width.
the other 2 dont make sense.
also kira I gave up after about 3 sentences that brick of text is very hard to read.
while it may have looked ok on your screen here is how it looks with my screen width.
Last edited:
Here, I fixed it for you:
Hello,
INTRO:
I'm making this post to offer my observations, assumptions and conclusions on CVTs-Constantly Variable Transmissions. I want comment, correction, questions and experiences from everyone. My interest in these transmissions peaked recently when my sister was shopping for a new car.
HISTORY:
In the 1970's magazines ran stories on the "stepless transmission". I believe CVTs were put on the back burner because they weren't needed. Any benefit related to the 70's energy crisis diminished as the gas lines vanished. More recent history made it clear that energy was going to be a volatile commodity, with rising prices, forever.
WHAT I THINK HAPPENED:
The designs for CVTs were revised, I'm guessing, for use with much smaller engines as well as electric motor hybrid applications. They're predisposed to smaller engines. Fitting an early CVT to the Ford FIVE HUNDRED was a huge failure. Ford couldn't keep up with the volume of transmission swaps, I was told. Still today, car companies are coupling CVTs to their off-the-shelf engines. Heck, Honda's conventional transmissions suffered for a long time due to the weakness of their units. The engines got bigger, the cars got heavier and their transmissions were caught in the middle-literally. That is what the legacy of early CVTs will be, I think.
OBSERVATIONS AND HEARSAY:
1) One car company refers to their CVT as a 6 speed. While a CVT might be programmed to use, say, 6 predominating ratios; it doesn't sound like the namesake feature of these units is all that important in the first place. Perhaps they're already pushing the feature into obscurity. One has to ask why.
2) When I've accelerated in a CVT equipped vehicle it dropped into its lowest ratio abruptly causing the engine to wind up fast and loudly. With time will the adjustable cones slam to a limit and will the belt follow as it should?
3) An acquaintance with a garage has reported that that his customers feel occasional shuddering caused by the belt not maintaining full or even contact on its pulleys. He has to allay fears involving products he didn't sell. Tell me, when does chattering improve over time?
4) Another mechanic made a great conversational point by saying, "Hey, they only just perfected regular automatics. Now they're fooling around with these things."
CONCLUSIONS:
1) I feel CVTs are at the toddler stage. What's so bad about the car industry is that each feature needs development and the several auto companies will access varying outside firms, have access to only some of the better patents and amass different reliability data. Thus, sub-assemblies of the CVT will develop in a herky jerky manner. Remember, even today's improved Hondas have weak torque converters. This is a case where companies have to collude to shorten the consumer's "guinea pig" stage.
2) Gas is still cheap and Americans love to step on the pedal. We love oomph and auto makers are loathe to downsize their products. The bottom line is cheap, spottily engineered CVTs will be overpowered. They'll loosen and/or burn up.
CONCLUSIONS:
1) A CVT has fewer parts, is cheaper to build and the industry wants to use it. This industry has a track record of marketing some really bad products so you can't trust them. They appeal to one's feelings not one's needs. And you can fully discount any "business class" claim that advertising educates a consumer. 2) A Subaru salesman said to us, "We've been making a CVT for over 25 years." I'd love to know the details. He didn't have them at the ready.
3) For my money, a car company can install CVTs on fleet vehicles and report what they learn. DISCLAIMER: I'm not a member of the Stepped Transmission Lovers Association or anything like that. Thanks for reading. Kira
Hello,
INTRO:
I'm making this post to offer my observations, assumptions and conclusions on CVTs-Constantly Variable Transmissions. I want comment, correction, questions and experiences from everyone. My interest in these transmissions peaked recently when my sister was shopping for a new car.
HISTORY:
In the 1970's magazines ran stories on the "stepless transmission". I believe CVTs were put on the back burner because they weren't needed. Any benefit related to the 70's energy crisis diminished as the gas lines vanished. More recent history made it clear that energy was going to be a volatile commodity, with rising prices, forever.
WHAT I THINK HAPPENED:
The designs for CVTs were revised, I'm guessing, for use with much smaller engines as well as electric motor hybrid applications. They're predisposed to smaller engines. Fitting an early CVT to the Ford FIVE HUNDRED was a huge failure. Ford couldn't keep up with the volume of transmission swaps, I was told. Still today, car companies are coupling CVTs to their off-the-shelf engines. Heck, Honda's conventional transmissions suffered for a long time due to the weakness of their units. The engines got bigger, the cars got heavier and their transmissions were caught in the middle-literally. That is what the legacy of early CVTs will be, I think.
OBSERVATIONS AND HEARSAY:
1) One car company refers to their CVT as a 6 speed. While a CVT might be programmed to use, say, 6 predominating ratios; it doesn't sound like the namesake feature of these units is all that important in the first place. Perhaps they're already pushing the feature into obscurity. One has to ask why.
2) When I've accelerated in a CVT equipped vehicle it dropped into its lowest ratio abruptly causing the engine to wind up fast and loudly. With time will the adjustable cones slam to a limit and will the belt follow as it should?
3) An acquaintance with a garage has reported that that his customers feel occasional shuddering caused by the belt not maintaining full or even contact on its pulleys. He has to allay fears involving products he didn't sell. Tell me, when does chattering improve over time?
4) Another mechanic made a great conversational point by saying, "Hey, they only just perfected regular automatics. Now they're fooling around with these things."
CONCLUSIONS:
1) I feel CVTs are at the toddler stage. What's so bad about the car industry is that each feature needs development and the several auto companies will access varying outside firms, have access to only some of the better patents and amass different reliability data. Thus, sub-assemblies of the CVT will develop in a herky jerky manner. Remember, even today's improved Hondas have weak torque converters. This is a case where companies have to collude to shorten the consumer's "guinea pig" stage.
2) Gas is still cheap and Americans love to step on the pedal. We love oomph and auto makers are loathe to downsize their products. The bottom line is cheap, spottily engineered CVTs will be overpowered. They'll loosen and/or burn up.
CONCLUSIONS:
1) A CVT has fewer parts, is cheaper to build and the industry wants to use it. This industry has a track record of marketing some really bad products so you can't trust them. They appeal to one's feelings not one's needs. And you can fully discount any "business class" claim that advertising educates a consumer. 2) A Subaru salesman said to us, "We've been making a CVT for over 25 years." I'd love to know the details. He didn't have them at the ready.
3) For my money, a car company can install CVTs on fleet vehicles and report what they learn. DISCLAIMER: I'm not a member of the Stepped Transmission Lovers Association or anything like that. Thanks for reading. Kira
I read an article--blurb, really--about how automakers are going to be offering 7, 8, 9 and 10 speed transmissions in the future. 7 and 8 speeds are around today, not sure if anyone is using 10 speed out of tractor-trailers. I'd think somewhere around there CVT's would come into vogue, due to gears simply getting too thin or otherwise unable to cope with the power. [Or if you reduce torque of the engine, well, then you are fixing what used to break CVT's in the first place.]
I think the manufacturers are going to do a much better job this time in making transmissions last 100kmiles and beyond. Might even make it to 150k. Problem is, a number of persons on BITOG etc tend to drive even further. How much it will cost to rebuild/repair a CVT will be interesting--albeit I don't think it's free to rebuild/repair a manual transmission nor conventional automatic.
Ditto on the need for paragraphs... Or at least hit "enter" after your numbered points.
I think the manufacturers are going to do a much better job this time in making transmissions last 100kmiles and beyond. Might even make it to 150k. Problem is, a number of persons on BITOG etc tend to drive even further. How much it will cost to rebuild/repair a CVT will be interesting--albeit I don't think it's free to rebuild/repair a manual transmission nor conventional automatic.
Ditto on the need for paragraphs... Or at least hit "enter" after your numbered points.
Hello, Continuously - constantly....sorry. I realized it was long. The point was to share my thoughts and those of my car contacts. I hope more people will offer real life experiences as Clevy did. And thanks Nate, for editing. I tried to do that. Kira
tl;dr
I think regular autos have not really been "perfected" but rather are regressing as companies make them more complex, weaken them in the name of efficiency, and spectacularly fail at making them "smart" to learn the drivers behavior.
The old 4 speeds churn along while new new autos brains die, flutter shift, and grind to a halt as one of the seventeen gear control solenoids go bad.
Maybe someday they will get it right. K.I.S.S.
The old 4 speeds churn along while new new autos brains die, flutter shift, and grind to a halt as one of the seventeen gear control solenoids go bad.
Maybe someday they will get it right. K.I.S.S.
My old AW-4 will keep going. It's the slushbox of sludhboxes, but it's reliable.
With some of these new cars, only see manual as an option. I don't want a 9 speed automatic (especially if it's from chrysler), I don't ant a $7k CVT.
I'm going to have to stick with my 5 / 6 speed manual.
With some of these new cars, only see manual as an option. I don't want a 9 speed automatic (especially if it's from chrysler), I don't ant a $7k CVT.
I'm going to have to stick with my 5 / 6 speed manual.
Originally Posted By: SOHCman
I think regular autos have not really been "perfected" but rather are regressing as companies make them more complex, weaken them in the name of efficiency, and spectacularly fail at making them "smart" to learn the drivers behavior.
The old 4 speeds churn along while new new autos brains die, flutter shift, and grind to a halt as one of the seventeen gear control solenoids go bad. The old GM turbohydramatic was a great transmission, at keast until GM "downsized" applications. Of course having plenty of torque available from the engine made for nice operation. That transmission was good enough that Rolls used it.
Maybe someday they will get it right. K.I.S.S.
I think regular autos have not really been "perfected" but rather are regressing as companies make them more complex, weaken them in the name of efficiency, and spectacularly fail at making them "smart" to learn the drivers behavior.
The old 4 speeds churn along while new new autos brains die, flutter shift, and grind to a halt as one of the seventeen gear control solenoids go bad. The old GM turbohydramatic was a great transmission, at keast until GM "downsized" applications. Of course having plenty of torque available from the engine made for nice operation. That transmission was good enough that Rolls used it.
Maybe someday they will get it right. K.I.S.S.
7 and 8 speed transmissions do not necessarily have more parts than 4 or 5 speed transmissions. You can get many different gear ratios out a single planetary gearset.
A conventional auto with a lot of gears would be good for a PCCI/HCCI engine as it runs in a relatively limited RPM and load range.
I think you're wrong on the Ford/ZF transmission as being a "failure". It's a failure in that Ford gave up on it, but you're greatly overstating the problems with it. Maybe bdcardinal can throw in his $.02 as to how many they see in for repair that weren't improperly serviced, i.e. wrong fluid.
There were a small number of failures due to the input shaft failing, but those were the overwhelming minority. The dealer from whom I buy parts told me they've seen a few over 200K miles, and they've had very few transmission repairs on them. I'm at 135K and it drives like new. My guess is that cost was really the reason they went away from the CVT. Most of the independent data out there reflect that they've been reliable (Identifix, True Delta).
My preference is a manual transmission, but in lieu of that I'll take a CVT over a stepped automatic any day. 1,400 rpm @ 60mph, good passing power when the torque convert locks down and no jerky shifting. Jatco has been making chain-drive CVT's for a good chunk of time now, so I'd trust the Jatco-derived Subaru transmissions.
There were a small number of failures due to the input shaft failing, but those were the overwhelming minority. The dealer from whom I buy parts told me they've seen a few over 200K miles, and they've had very few transmission repairs on them. I'm at 135K and it drives like new. My guess is that cost was really the reason they went away from the CVT. Most of the independent data out there reflect that they've been reliable (Identifix, True Delta).
My preference is a manual transmission, but in lieu of that I'll take a CVT over a stepped automatic any day. 1,400 rpm @ 60mph, good passing power when the torque convert locks down and no jerky shifting. Jatco has been making chain-drive CVT's for a good chunk of time now, so I'd trust the Jatco-derived Subaru transmissions.
Originally Posted By: Miller88
My old AW-4 will keep going. It's the slushbox of sludhboxes, but it's reliable.
With some of these new cars, only see manual as an option. I don't want a 9 speed automatic (especially if it's from chrysler), I don't ant a $7k CVT.
I'm going to have to stick with my 5 / 6 speed manual.
Aren't Chrysler sourcing their many-speed AT's from ZF?
My old AW-4 will keep going. It's the slushbox of sludhboxes, but it's reliable.
With some of these new cars, only see manual as an option. I don't want a 9 speed automatic (especially if it's from chrysler), I don't ant a $7k CVT.
I'm going to have to stick with my 5 / 6 speed manual.
Aren't Chrysler sourcing their many-speed AT's from ZF?
Originally Posted By: Kira
Fitting an early CVT to the Ford FIVE HUNDRED was a huge failure. Ford couldn't keep up with the volume of transmission swaps, I was told.
Proof? One of my good friends is a Ford double Senior Master Tech and the only trans tech at his dealership. He's replaced 2 CVTs and 1 or 2 mechatronic assemblies since the Freestyle/Five Hundred CVT came out in 2005 due to actual trans problems. IIRC, he's replaced a couple more due to them being serviced with regular ATF, which is no fault of the CVT. CFT30 failure rates are actually quite low statistically.
Fitting an early CVT to the Ford FIVE HUNDRED was a huge failure. Ford couldn't keep up with the volume of transmission swaps, I was told.
Proof? One of my good friends is a Ford double Senior Master Tech and the only trans tech at his dealership. He's replaced 2 CVTs and 1 or 2 mechatronic assemblies since the Freestyle/Five Hundred CVT came out in 2005 due to actual trans problems. IIRC, he's replaced a couple more due to them being serviced with regular ATF, which is no fault of the CVT. CFT30 failure rates are actually quite low statistically.
Nissan upped the warranty coverage on their CVT option. I think up to 120K miles (I don't recall the number of years, 5???)
I suspect many of the failures are due to using the wrong fluid if they are serviced. The concept seems sound. The question is are the materials used up to the task. I.E. the fluids, the friction materials in the units.
Then there is getting accustomed to the driving experience. I can say that I don't like driving the CVT in my wife's 2.5L Altima. Not that it's bad, it's just different. But then I come from a daily driver of a manual transmission Protege5, so that's my bias.
I suspect many of the failures are due to using the wrong fluid if they are serviced. The concept seems sound. The question is are the materials used up to the task. I.E. the fluids, the friction materials in the units.
Then there is getting accustomed to the driving experience. I can say that I don't like driving the CVT in my wife's 2.5L Altima. Not that it's bad, it's just different. But then I come from a daily driver of a manual transmission Protege5, so that's my bias.
Originally Posted By: SOHCman
I think regular autos have not really been "perfected" but rather are regressing as companies make them more complex, weaken them in the name of efficiency, and spectacularly fail at making them "smart" to learn the drivers behavior.
+1
I think regular autos have not really been "perfected" but rather are regressing as companies make them more complex, weaken them in the name of efficiency, and spectacularly fail at making them "smart" to learn the drivers behavior.
+1
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