CVT's

[hotrodalex]

The concept is cool, so I voted yes. The application of them is sort of lacking, however. But I still approve of further tinkering to see if they can end up being a great technology.

[Colin]

What a load of drivel there is in this thread.

The theory of a CVT is that by being able to adjust the gearing constantly, you are always in the right ratio for the speed and engine loading, as opposed to having to be in one of a series of fixed ratios. Early CVTs - and I recall with some horror the Selecta system that Ford used in the 1990s Fiesta and Fiat in the Panda and Uno - were not very good as there was always a lag between what the throttle or brakes did and the transmission catching up, making it very difficult to drive smoothly. They were generally worse when you braked hard than they were when you accelerated hard.

Since those dark days, the technology has improved massively, so most CVTs in my experience are now fairly smooth. As mfrs have moved from standard 4 speed traditional boxes to ones with more ratios, typically with the top 3 or 4 gears quite close together, you can indeed get the scenario where the box does hunt between the gears a bit, but unless you get a particularly torque-less car, since most of them are quite smooth so you should not really be aware that this is going on. If you are driving hard, there is unlikely to be constant ratio shifting.

[cawimmer430]

I've only driven the Mercedes Autotronic CVTs. on the W169 and W245 A/B-Classes.

On the powerful gasoline models they're ok.

On the weaker gasoline models they're a pain in the ass.

On all diesels they're ok.

[giant_mtb]

I drove a Subaru Legacy with a "Lineartronic" CVT twice over the summer (repeat customer!).  I didn't mind it, but the thing was so damn powerless to begin with that the CVT made the acceleration feel like a turtle's.  I opted to use the paddle shifters/artificial gears instead.

[2o6]

What a load of drivel there is in this thread.

The theory of a CVT is that by being able to adjust the gearing constantly, you are always in the right ratio for the speed and engine loading, as opposed to having to be in one of a series of fixed ratios. Early CVTs - and I recall with some horror the Selecta system that Ford used in the 1990s Fiesta and Fiat in the Panda and Uno - were not very good as there was always a lag between what the throttle or brakes did and the transmission catching up, making it very difficult to drive smoothly. They were generally worse when you braked hard than they were when you accelerated hard.

Since those dark days, the technology has improved massively, so most CVTs in my experience are now fairly smooth. As mfrs have moved from standard 4 speed traditional boxes to ones with more ratios, typically with the top 3 or 4 gears quite close together, you can indeed get the scenario where the box does hunt between the gears a bit, but unless you get a particularly torque-less car, since most of them are quite smooth so you should not really be aware that this is going on. If you are driving hard, there is unlikely to be constant ratio shifting.

Ah HA! Thank you....someone who feels the same way I do.


Granted, not all CVT's are equal; some aren't adept at particularly great throttle response. But the CVT will always pick the most efficient ratio for the load and power demand at the time. That (plus the smoothness) really gets me going. I really don't understand the "drone" issue; when you stop accelerating, it backs off and finds a better ratio for economy (and sound). Heck, with big engines, like the Nissan V6es, I can't get it to redline "shift".


Besides, artificial gears usually make the car slower.

[sportyaccordy]

My car has six gears and I always know what gear to put it in. Most 6 speed autos are fine.

[Raza]

At understanding what gear to use.  I mean, if I can always know what to do with my 6 speed, surely the almighty computer can know what's best for me without fail, right?

[2o6]

At understanding what gear to use.  I mean, if I can always know what to do with my 6 speed, surely the almighty computer can know what's best for me without fail, right?

[Raza]

If a 6 speed is hunting gears, then it's a bad program.  It's not that 6 gears is too many, since loads of people drive 6 speed manuals and never don't know what gear to use. 

[2o6]

If a 6 speed is hunting gears, then it's a bad program.  It's not that 6 gears is too many, since loads of people drive 6 speed manuals and never don't know what gear to use. 

And the thread's topic is about AUTOMATIC transmissions. Who cares if the human knows what gear to pick, it's not what this thread is about. There are a lot of indecisive transmissions (especially with little engines) that never know what ratio to select.

[Raza]

And the thread's topic is about AUTOMATIC transmissions. Who cares if the human knows what gear to pick, it's not what this thread is about. There are a lot of indecisive transmissions (especially with little engines) that never know what ratio to select.

You were speaking as if the problem were inherent to the number of gears.  It's a programming issue, not a number of gears issue.  If the Sonic had shitty AT programming, that's software, not hardware.

[2o6]

You were speaking as if the problem were inherent to the number of gears.  It's a programming issue, not a number of gears issue.  If the Sonic had shitty AT programming, that's software, not hardware.

Cruze.

It tends to go hand in hand to a certain extent.

[Raza]

Cruze.

It tends to go hand in hand to a certain extent.

Bad software is bad software, it's not bad hardware.  It's like blaming computer's processor for your OS being bad.

[CJ]

Our Sonata transmission seems to know what it's doing. Always ready for a downshift and knows what gear it should be in.


The Honda hunts.

[Raza]

Our Sonata transmission seems to know what it's doing. Always ready for a downshift and knows what gear it should be in.


The Honda hunts.

My dad's 8 speed hunts, my mom's 7 speed doesn't, my brother's 6 speed (DSG) doesn't. 

[SVT666]

If a 6 speed is hunting gears, then it's a bad program.  It's not that 6 gears is too many, since loads of people drive 6 speed manuals and never don't know what gear to use.  

If a 6 speed is hunting then the ratios are too tight, it's bad programming, or the engine isn't powerful enough to hold gears.

[Laconian]

Bad software is bad software, it's not bad hardware.  It's like blaming computer's processor for your OS being bad.

+5000

[cawimmer430]

I've got no complaints about the 6-speed A/T in the BMW 118i. Works rather well with the "little" motor and it's "underpowered" 143-horsepower. 

[sportyaccordy]

I forget where I saw it but there's a vid of the 528i with the 8AT operating beautifully

The problem is really them trying to game the trannys to beat the EPA fuel economy test... w/o that programming would be simple

[sportyaccordy]

I've got no complaints about the 6-speed A/T in the BMW 118i. Works rather well with the "little" motor and it's "underpowered" 143-horsepower. 

Why do you continue to say these things, when many if not most folks here drive cars w/less horsepower

I just did a positive review on a 75HP Fiat Panda

How long are you going to drag these stupid jokes on

[cawimmer430]

How long are you going to drag these stupid jokes on

1/4 mile... 


Lighten up! 

[nickdrinkwater]

I would have a CVT.  I think they're better on fuel than a "normal" CVT and sometimes better than the manual.  It depends on the car though as always

[hotrodalex]

I want a manual CVT.

[Northlands]

Bad software is bad software, it's not bad hardware.  It's like blaming computer's processor for your OS being bad.

[Northlands]

I don't mind the existence of CVT transmissions, but they just aren't for me.

I don't enjoy the audio experience mainly. I'm not a fan of the electric train sounds that I associate with CVT geared vehicles. I know there's a lot of poorly programmed auto transmissions out there, but there's a certain satisfaction of hearing the revs drop and rise.

[AutobahnSHO]

With the costs of everything computer-related coming down, WHY OH WHY do they not put "inclinometers" in the cars? Then the auto transmission knows as you are going up a hill it will need to shift- and as you are still on the shift, don't shift up/down/up/down/up/down until the hill is done.

Some with coasting DOWN a hill- if you're hard on the brakes over and over it could keep it in a lower gear..

[Laconian]

??? They certainly do have that. Toyota ATs have been pitching in with engine braking since at least 2004 (when I noticed it in a Scion xB).

[MexicoCityM3]

With the costs of everything computer-related coming down, WHY OH WHY do they not put "inclinometers" in the cars? Then the auto transmission knows as you are going up a hill it will need to shift- and as you are still on the shift, don't shift up/down/up/down/up/down until the hill is done.

Some with coasting DOWN a hill- if you're hard on the brakes over and over it could keep it in a lower gear..

They put those in. Since a long time ago. My E46 323i (automatic) held gears beautifully in D.

[Laconian]

My car blip-downshifts and engine brakes when I go down hills in Sport.

[AutobahnSHO]

When will the rest of them get inclinez????