Changing my opinion on CVTs - I kind of like them!

[emg]

Originally Posted By: SteveSRT8
But they do extrapolate reliability ratings out of thin air for cars that are brand new!


Not really that hard, if the new cars use existing engines and transmissions. It's not as though manufacturers toss millions of new cars out on the road to see how reliable they are, they're doing similar calculations internally.

Yes, they might have new faults, but that's why it's predicted reliability, not measured.

Quote:
Of course they will never be used in any real high torque apps without some sort of breakthrough, but they work well in most cars biased towards fuel economy...


I can't find a number for torque, but the Williams/Renault CVT car that was banned from racing for being too good had nearly 800bhp. At one point, Lotus were going to put a CVT in their first V8 road car in the 80s, though that probably wasn't particularly powerful by modern standards.

 

[Pops1050]

Application is key with these transmissions. Drove a Murano 4 - 5 yrs ago and it was a little wierd the way the engine revved, kinda out of sync with desired acceleration. I drove my daughters '14 Accord this week and was really pleased overall. Noise wasn't an issue at all and because of the ratio range at 75mph engine rpm was ~2000 rpm. That's about 500 or so less than the wifes '07 Accord at the same speed. Also didn't have that disconnected feel driving around town. If CVT's prove reliable looks to me to be the way to go in these people movers. Performance cars, maybe not so much.

 

[Kira]

Hello, FINALLY two dozen responders on the subject!
I posted a piece here (OK, a little long) with my observations on CVT's and requested feedback.
All I got was whining and "whadayamean"s. Perhaps CVT's were too new at that time.

The gist of my post was that the darn things were designed decades ago either for Subarus "legendary" forest service vehicles (anybody ever seen a picture of one?) or snowmobiles.

I theorize that the designs were dusted off during the last "gas shortage". Everyone expected cars to get smaller.

They didn't. The tooling was cast and the industry had to go ahead and make good on their investment.
"Hey, why not?", the execs must've said to themselves. "They have fewer moving parts and we can't look like we don't know how to manage a car company".

Ford couldn't keep CVT's for their fivehundred (Taurus replacement) in stock.
Now we're talking about 3.5L engines feeling good with them. Sure, but for how long?

1) A kid in a transmission shop mentioned that it "...took 'em 60 years to get regular automatics perfected. You want to go with a CVT NOW?"
100% air-tight logic, NO. 100% 'sounds good', YES.

2) FROM THIS THREAD: "...some type of sensor that is used to evaluate it. I believe the only way to get actual physical access to the fluid is to drop the pan.
Subaru early on had some problems with the fluid change not being done properly and failure happening soon after, I think that's one reason its not a scheduled maintenance any longer."

Would you want to patronize a company that employed that kind of foolishness? I wouldn't.
At least they kept the pan.

3)Please keep in mind that CVT's weren't "featured equipment" on cars.
It seemed to me that car dealers went out of their way to bury the fact that a car was CVT equipped.
If they're so groovy, why did/do car companies say their cars are 7, 8 or 9 speed when they have a CVT?
They know the units are weak garbage. OK, weak evolving garbage

4) In the name of equal time, my friends like their CVT equipped Mitsubishi Outlanders (a 2013 and a 2011 sold to a friend). Both have the 2.4L 4 cyl.

5) On a personal note: I firmly believe that the last thing you want to do with any CVT is floor it! A metal belt which doesn't contact its drums shouldn't be slammed around.
WHACKA-whacka bang-bang! Kira

 

[Pops1050]

Kira,
You said "evolving" and I think that is key here too. If the CVT becomes more commonplace it'll have to be reliable/servicable. I mean in reality most folks have NO idea what kind of tranny their ride has and as I said in people toters (example,daughters Accord) they seem to work. For the fella who cares about such things they may never be acceptable. 2 cents

 

[dlayman]

Originally Posted By: Kira
Hello, FINALLY two dozen responders on the subject!
I posted a piece here (OK, a little long) with my observations on CVT's and requested feedback.
All I got was whining and "whadayamean"s. Perhaps CVT's were too new at that time.

The gist of my post was that the darn things were designed decades ago either for Subarus "legendary" forest service vehicles (anybody ever seen a picture of one?) or snowmobiles.

I theorize that the designs were dusted off during the last "gas shortage". Everyone expected cars to get smaller.

They didn't. The tooling was cast and the industry had to go ahead and make good on their investment.
"Hey, why not?", the execs must've said to themselves. "They have fewer moving parts and we can't look like we don't know how to manage a car company".

Ford couldn't keep CVT's for their fivehundred (Taurus replacement) in stock.
Now we're talking about 3.5L engines feeling good with them. Sure, but for how long?

1) A kid in a transmission shop mentioned that it "...took 'em 60 years to get regular automatics perfected. You want to go with a CVT NOW?"
100% air-tight logic, NO. 100% 'sounds good', YES.

2) FROM THIS THREAD: "...some type of sensor that is used to evaluate it. I believe the only way to get actual physical access to the fluid is to drop the pan.
Subaru early on had some problems with the fluid change not being done properly and failure happening soon after, I think that's one reason its not a scheduled maintenance any longer."

Would you want to patronize a company that employed that kind of foolishness? I wouldn't.
At least they kept the pan.

3)Please keep in mind that CVT's weren't "featured equipment" on cars.
It seemed to me that car dealers went out of their way to bury the fact that a car was CVT equipped.
If they're so groovy, why did/do car companies say their cars are 7, 8 or 9 speed when they have a CVT?
They know the units are weak garbage. OK, weak evolving garbage

4) In the name of equal time, my friends like their CVT equipped Mitsubishi Outlanders (a 2013 and a 2011 sold to a friend). Both have the 2.4L 4 cyl.

5) On a personal note: I firmly believe that the last thing you want to do with any CVT is floor it! A metal belt which doesn't contact its drums shouldn't be slammed around.
WHACKA-whacka bang-bang! Kira




I remember the Subaru Justy, a small three cylinder hatch that used cvt in late 80's. I'm no expert in these things, but my understanding is that they have been used in other countries for quite some time. My limited understanding is that they have fewer moving parts and are simpler in operation than conventional automatics. My only real problem is that most are sealed and unable or very difficult to service. At this point,a rebuild isn't possible as I understand and a complete replacement is necessary if it fails. The "lifetime fluid" bothers me a bit. What does that even mean? Anything can be a lifetime fluid, in that it functions until it fails, thus the end of its lifetime.
I would suspect that gentle driving practices go a long way to prolong longevity, and that the fluid is a pretty robust synthetic lubricant. It's possible the fluid could last 200k miles, but who knows. I still have the original power steering fluid and manual gear oil in my 05 civic (shame on me) after nearly 300k miles and had no problems. A tranny is another matter of course.

 

[Anthony]

Originally Posted By: SteveSRT8
Originally Posted By: Anthony
Miller88

Nissan extended the Warranties for consumer confidence because CVT's were not being fully accepted at the time. The idea of the transmission not shifting turned some people away.

They haven't been perfect, but they are pretty darn good IMO. The Altima continues to be on Consumer Reports recommended list.

They don't recommend vehicles that get bad reliability ratings.


But they do extrapolate reliability ratings out of thin air for cars that are brand new! CR is worthless IMO, you still get to trust them any way you want.

You did make a valid point about Nissan and their Jatco units. They have a ton of them out there, got to give them credit for commitment.

But the overwhelming complaint against them is all about PROGRAMMING, not design. Of course they will never be used in any real high torque apps without some sort of breakthrough, but they work well in most cars biased towards fuel economy...


I'm actually not a big fan of CR, but I thought they gathered date from consumer who purchased these vehicles??

The programming has gotten better.
My friends mom has an 07 Maxima with 160k that runs great. No CVT problems at all.
They get decent fuel economy, but that car wasn't one of the cars geared towards just fuel economy. Like I said there will always be some bad apples, but the ratio of bad ones out there vs numbers sold is not nearly as high as you believe.

You will find those complaints though. This is the internet.

 

[emg]

Originally Posted By: Kira
I firmly believe that the last thing you want to do with any CVT is floor it! A metal belt which doesn't contact its drums shouldn't be slammed around.
WHACKA-whacka bang-bang!


It's all computer controlled, with no direct link between gas pedal and engine. It won't go 'bang-bang' unless the programmers are idiots.

 

[SwampSurvivor]

CVTs are relatively common in the 3rd world on vehicles that don't have manual transmission. Most of the Fiji Kei trucks have CVTs. They make deliveries all day in China and Japan.

Tension is all that holds the belt to the drums. I could see flooring it causing some issues.

I bet they work well on the Nissan NV200 dustbuster taxi. I believe its the same one in the Versa. Seems like it would hold up decent in a Versa Note.

Lifetime means until it does! Haha.


Originally Posted By: emg
Originally Posted By: Kira
I firmly believe that the last thing you want to do with any CVT is floor it! A metal belt which doesn't contact its drums shouldn't be slammed around.
WHACKA-whacka bang-bang!


It's all computer controlled, with no direct link between gas pedal and engine. It won't go 'bang-bang' unless the programmers are idiots.


They do go bang bang ... at 50K miles or so according to reliability ratings

 

[lovcom]

The most dependable car in the world is the Toyota Prius. The Prius has a CVT and for years. It has no reputation for CVT problems. And driving a late model Prius shows the CVT is greatly refined. A far cry from nissans horrible implementation for CVT.

 

[SteveSRT8]

Originally Posted By: Anthony
Like I said there will always be some bad apples, but the ratio of bad ones out there vs numbers sold is not nearly as high as you believe.


Please be cautious saying what I believe, as in my post it doesn't even come close to saying anything about that at all.

And others should note that a Formula One CVT, a Prius CVT, and a Jatco CVT are wildly different designs and are simply called the same name for convenience. No blanket statements are valid unless first specifying the TYPE of CVT you are commenting on...

 

[emg]

Originally Posted By: Miller88
Tension is all that holds the belt to the drums. I could see flooring it causing some issues.


The CVT is designed for a specific torque level. So long as you don't exceed that torque, the belt shouldn't slip any more than it's designed to.

And, as I said, the gas pedal is just a sensor connected to the computers; it has no direct link to the engine any more. If the transmission is going to explode when you floor the gas, the programmers did their job wrong, because they have all the tools they need to coordinate engine and transmission response to the pedal to ensure nothing bad happens.

Quote:
They do go bang bang ... at 50K miles or so according to reliability ratings


Only a few brands have had major problems, and the ones that have failed were nothing to do with flooring the gas.

 

[emg]

Originally Posted By: SteveSRT8
And others should note that a Formula One CVT, a Prius CVT, and a Jatco CVT are wildly different designs and are simply called the same name for convenience. No blanket statements are valid unless first specifying the TYPE of CVT you are commenting on...


As far as I can determine from the limited info on the Internet, the Williams CVT was a belt/chain and pulley design similar to most current car CVTs.

This is the only diagram I could find:

Apparently the car idled at 12,500rpm and revved up to 15,000rpm once it got moving!

 

[Mr Nice]

I would avoid a car with CVT, unfortunately many manufacturers are headed that way of building their cars.

 

[grumpyoldman]

I still drive manuals because I like to pick my gear & shift point, which I find useful in just about every driving situation: icy roads, easy cruising, controlling downhill engine braking, long uphills, hard acceleration, etc. I even don't mind them in stop & go, for usually I just drop it into neutral.

I've never driven a CVT (as far as I know; some rental cars may have had them). How do they handle some of the more challenging situations, like icy roads? I often feather the clutch and/or use 2nd gear to control my traction. And downshifting for long downhills?

I did rent a car with paddle shifters once and hated it. For some reason my brain couldn't keep track of what gear I was in. I suppose in my home vehicles I'm much more used to the noise/feel/tach to tell me what's going on.

 

[IndyIan]

Originally Posted By: emg
Originally Posted By: SteveSRT8
And others should note that a Formula One CVT, a Prius CVT, and a Jatco CVT are wildly different designs and are simply called the same name for convenience. No blanket statements are valid unless first specifying the TYPE of CVT you are commenting on...


As far as I can determine from the limited info on the Internet, the Williams CVT was a belt/chain and pulley design similar to most current car CVTs.

This is the only diagram I could find:

Apparently the car idled at 12,500rpm and revved up to 15,000rpm once it got moving!

Also F1 motors(until recently) have very little torque, maybe 250ftlbs, as they make hp with revs.
The one common CVT system that could transfer a lot of torque is the one in the Prius, but its complicated by needing another motor that's either electrical or hydrostatic in the case of large Ag tractors.

 

[buster]

Drive the new WRX with the CVT. It's awesome.