Continuously Variable Transmissions (CVT)

[Judge]

Anyone out there with a new car with this new technology? Just wondering about it. I've always been partial to manual transmissions, but I suppose there's a possibility my next car may have a CVT instead.

Seems a bit scary to discover auto manufacturers so aggressively reinventing much more than just the wheel!

 

[Keigan]

Honda and Nissan have used them for 10+ years. Makes a great solution for improving fuel mileage, in that you can set the motor at it most efficient RPM and allow the CVT to alter the power between torque and HP.

 

[clg114]

When I was a young man, I had several vehicles with this kind of drive train. But they were all snowmobiles. The best thing about this system is how simple it is. There is a driving clutch and a driven clutch, with some kind of belt. The ramp on the driving clutch, starts with a small diameter and gets bigger the faster it turns. The driven clutch starts with a large diameter ramp and gets smaller the faster it turns. Both clutch's ramp diameter change at the same rate, so the belts tension stays adjusted. It is a ever changing gear ratio, very smooth with no shifts. I am thinking that it might feel strange in a car. Anybody got one?

 

[FreeDiver]

I am thinking that it might feel strange in a car. Anybody got one?

Not in a car. But out on the vineyard where I work on telemetry systems. We have these golf cart like ATV's that use the same belt drive CVT like they have on snowmobiles. As you accelerate, you feel the torque go down as your speed increases, all while your engine RPMs remain constant.

 

[Nitro]

My Polaris 4x4 has a belt style CVT like a snowmobile.

 

[Judge]

It is a ever changing gear ratio, very smooth with no shifts. I am thinking that it might feel strange in a car. Anybody got one?

Very interesting! I guess I'll probably take a test ride to see how they feel in accelerating. But I still am leaning towards another stick shift.

I've heard of the "rubber band" effect...that seems disconcerting to so many people. But then so many have been weaned on a conventional automatic tranny. Though I do get a bit skittish about anything mechanical using a "belt" as opposed to a chain.

 

[clg114]

People get used to a certain "feel" in the car that they drive. My wife's car is 14 Focus with a automatic transmission, but it does not have the same feel as a regular automatic. Because of that, most people hate them. It has a standard transmission that shifts it's self. If you close your eyes while riding in it, you get the sensation that you riding in a car with a regular standard trans. It is very complicated, with two clutch's and a driven shaft inside of another. But it works good and is trouble free. The only reason people do not like them is because they feel different. Go figure.

 

[FreeDiver]

People get used to a certain "feel" in the car that they drive. My wife's car is 14 Focus with a automatic transmission, but it does not have the same feel as a regular automatic. Because of that, most people hate them. It has a standard transmission that shifts it's self. If you close your eyes while riding in it, you get the sensation that you riding in a car with a regular standard trans. It is very complicated, with two clutch's and a driven shaft inside of another. But it works good and is trouble free. The only reason people do not like them is because they feel different. Go figure.

That type of transmission that you're talking about is called a "Dual Clutch Transmission". Here is a video explaining how it works.

There are a couple of downsides to these. 1). The ECT unit has to anticipate whether to downshift or upshift and if it gets it wrong. There is a substantial delay in the reengagement of the gear as it had to reverse the shift cycle. 2). There is a minimum coast speed you can drive at and if you try to go slower. You'll burn out the clutch from riding it. This is why first gear engages a little rough.

 

[clg114]

That type of transmission that you're talking about is called a "Dual Clutch Transmission". Here is a video explaining how it works.

There are a couple of downsides to these. 1). The ECT unit has to anticipate whether to downshift or upshift and if it gets it wrong. There is a substantial delay in the reengagement of the gear as it had to reverse the shift cycle. 2). There is a minimum coast speed you can drive at and if you try to go slower. You'll burn out the clutch from riding it. This is why first gear engages a little rough.

Thank you for the video. I had never seen that one before and it was very interesting. When we first got the car I heard a little about it. That made the Aspie in me come out and I researched how the trans works. I hope that I never have to work on it.

 

[Judge]

Anyone here know what the significance of a defective "input shaft bearing" is relative to the transmission?

That's what's prompting me to post questions about the latest new car technology.

 

[Keigan]

Input shaft bearing, depends on the transmission. On a manual, you have a pilot bearing inside of the crankshaft tail that the transmission input shaft rides within and the manual clutch rides on the input shaft. On the transmission side the input shaft transfers power from the motor into the transmission, the input shaft rides on a bearing inside of the transmission.

Pilot bearings do wear and can cause a lot of noise when the clutch engages. Input shaft bearings can produce more of a whine as they wear.

 

[Judge]

Input shaft bearings can produce more of a whine as they wear.

Oh yeah. Tell me about it! Makes the noise accelerating or decelerating in 2nd thru 5th gear and is becoming a little noticeable in 6th. And disappears when the clutch is engaged.

In my case it turned out to be one of those "dirty little secrets" Toyota didn't want to talk about. The cost of a tranny rebuild that goes with replacing that particular bearing would well exceed the remaining value of the car. Damn shame for having few other issues over seventeen years.

Thus why I have immersed myself into learning of the most recent car technologies. Which in the past was usually fun with zero apprehension.

CVT, stop/start technology, and how keyless entry systems can be completely hacked. Not good. With so much emphasis on fuel consumption and so little on raw performance. WTF ?

 

[Keigan]

2008 Ford F450 CrewCab Longbed 4x4 Auto 6.4L twin sequential turbos, lariat with a sunroof. Currently +700ft pounds of torque and 420hp.

Big smile.

Did I mention the sunroof?!

At 50mph I get 22mpg.
At 60mph I get 18mpg.
At 70mph I get 14mpg.
At 80mph I get 12mpg.

Aero-dynamics of a barn door.

 

[Keigan]

And, I could drive over the top of a Toyota Prias and not even recognize it as a speed bump.

 

[clg114]

Oh yeah. Tell me about it! Makes the noise accelerating or decelerating in 2nd thru 5th gear and is becoming a little noticeable in 6th. And disappears when the clutch is engaged.

In my case it turned out to be one of those "dirty little secrets" Toyota didn't want to talk about. The cost of a tranny rebuild that goes with replacing that particular bearing would well exceed the remaining value of the car. Damn shame for having few other issues over seventeen years.

Thus why I have immersed myself into learning of the most recent car technologies. Which in the past was usually fun with zero apprehension.

CVT, stop/start technology, and how keyless entry systems can be completely hacked. Not good. With so much emphasis on fuel consumption and so little on raw performance. WTF ?

That is not the only the only "dirty little secret" that Toyota has about their transmissions. Toyota is not only the worlds largest seller of cars, but of forklifts too. One of the most popular models has dual electric drive motors, one for each front wheel. Since forklifts do not go very fast, they have a reduction transmission between the drive motor and the drive wheel. Sometime shortly after the hour meter turns over for the first time, these transmissions start failing at a alarming rate. The cost for parts for a rebuild is in the $2000 area and that's not counting labor! I have a customer that bought eight of them in 2010. Now they are all in the boneyard with one problem, the transmissions.

 

[Judge]

That is not the only the only "dirty little secret" that Toyota has about their transmissions. Toyota is not only the worlds largest seller of cars, but of forklifts too. One of the most popular models has dual electric drive motors, one for each front wheel. Since forklifts do not go very fast, they have a reduction transmission between the drive motor and the drive wheel. Sometime shortly after the hour meter turns over for the first time, these transmissions start failing at a alarming rate. The cost for parts for a rebuild is in the $2000 area and that's not counting labor! I have a customer that bought eight of them in 2010. Now they are all in the boneyard with one problem, the transmissions.

Uh huh. That's why I've surmised that I must begin looking for a new car. Otherwise what it will take to restore my car would exceed half the cost of a brand new one. Actually I feel grateful that I went this far paying only for maintenance, insurance, tires, a water pump and a battery.

But then I've never even come close to owning any car this long. It was a good run, but things are only going to get worse with time. And the cost...well...$2000 + labor for a forklift. You know where this is going. That cost to replace my input shaft bearing in my transmission cost a few times beyond the bluebook value of the car. Making it a bad investment, especially considering all the other components needing replacement now or in the near future.

 

[clg114]

Uh huh. That's why I've surmised that I must begin looking for a new car. Otherwise what it will take to restore my car would exceed half the cost of a brand new one. Actually I feel grateful that I went this far paying only for maintenance, insurance, tires, a water pump and a battery.

But then I've never even come close to owning any car this long. It was a good run, but things are only going to get worse with time. And the cost...well...$2000 + labor for a forklift. You know where this is going. That cost to replace my input shaft bearing in my transmission cost a few times beyond the bluebook value of the car. Making it a bad investment, especially considering all the other components needing replacement now or in the near future.

I think that you have the right idea. Seventeen years is a long time to drive a car. It sounds like you more than got your moneys worth out of the car. It has served you well. But with a expensive repair on the horizon, it is time to sell it while it is still drivable and get something else. Who knows? The whole experience might be fun. Good luck.

 

[Judge]

I think that you have the right idea. Seventeen years is a long time to drive a car. It sounds like you more than got your moneys worth out of the car. It has served you well. But with a expensive repair on the horizon, it is time to sell it while it is still drivable and get something else. Who knows? The whole experience might be fun. Good luck.

Yeah, it hurt to come to this decision. But number-crunching is my stock and trade. I can't lie to myself under such circumstances. Though the tragedy of it all is twofold. I loved the car, and that no-kidding- it has only about 62K in original mileage. Sustaining a long commute for less than one year tops.

The dealer always chuckles to see me come in. From their POV most Celica GTS models went to junk pile. Not on reliability issues, but because the kids trashed them. Same reason you don't see a lot of sports cars on the road over time.

 

[Judge]

That type of transmission that you're talking about is called a "Dual Clutch Transmission". Here is a video explaining how it works.

There are a couple of downsides to these. 1). The ECT unit has to anticipate whether to downshift or upshift and if it gets it wrong. There is a substantial delay in the reengagement of the gear as it had to reverse the shift cycle. 2). There is a minimum coast speed you can drive at and if you try to go slower. You'll burn out the clutch from riding it. This is why first gear engages a little rough.

Looks like those "downsides" are on the rise, with that particular technology losing favor. Another thing to note in contemplating looking for a new car. <sigh>

Then again maybe I'll just stick with a manual transmission.

Ford's Dual-Clutch Transmission Could Spell Danger For Its Future

 

[clg114]

Looks like those "downsides" are on the rise, with that particular technology losing favor. Another thing to note in contemplating looking for a new car. <sigh>

Then again maybe I'll just stick with a manual transmission.

Ford's Dual-Clutch Transmission Could Spell Danger For Its Future

Wow! I did not realize that they were that big of a problem. That video makes me feel lucky that we have not had any trouble with ours. It still is not something that I like hearing about. Now I have permanently crossed fingers.