I have three questions about automakers and CVTs.

hexadtom

THOMAS

Apr 4, 22:31 EDT

1. Do any car manufacturers make CVT transmissions that do not mimic automatics or that allow you to turn off the mimic function?
2. Does not the mimic function of a CVT defeat the purpose of a CVT (selecting from a continuous range of gear ratios) by limiting the selection to those few ratios it is mimicking?
3. If #2 is true would it not be more efficient to utilize the infinite range available to a truly continuously variable system (not to mention a much smoother and, to my thinking, much more pleasant, ride)?

kyfdx

Those are really good questions. I hope someone has answers for you.

PF_Flyer

We'd been driving nothing but manual transmissions since 1979 when we got a vehicle with a CVT 4 years ago because a manual wasn't available in the model. While it doesn't make me a CVT expert, at least it gives me a decent amount of experience with them to have some opinions that you might find interesting.

The reason they have them mimic automatic transmission, as far as I can tell, is that if it were just a continuously variable range, with no "shift points" happening, the vast majority of us wouldn't like the "feel". Heck, I'm not overly comfortable with the feel as is after 4 years.

I don't think those "shift points" are limiting things to a fixed set of "gears", at least not that I've noticed. It seems more like the "shift" occurs at those points where you'd expect to feel something happen. Perfect example... if I'm starting up slowly, like starting up at a red light where I'm not accelerating hard, the "shift" happens fairly early and I'm in "top gear" pretty quickly. If I'm in a spot where I need to go hard, like accelerating to get onto the highway, the load will keep me in the lower range longer before the "shift" occurs.

As far as I can tell, the range IS continuously variable, there's just that one spot, depending on conditions where you transition from the lower variable range to the higher one. There's also a button on the shift lever to turn off overdrive and keep you in a lower range. Let's you "downshift" going down a long grade instead of riding the brakes.

The CVT is disconcerting enough the first time you try to stomp on it to merge onto a high speed road. It definitely took time to get used to the feel. If it didn't feel like a shift happened. it would drive me crazy.

Another reference point, I had a'73 Chevy Vega at one point that had a 2 speed automatic. One shift point, and THAT was annoying.

I don't want to say that the "programmed shift points" are purely cosmetic, but how the vehicle feels when you drive is important. And from a mechanical point of view, you DO need a lower gear/lower CVT range to get a vehicle moving, and that IS going to feel different than going along steady at 60MPH. Even at 60, if I stomp on it to make a pass or get out of a spot, having the feel of a "shift" lets my brain know I'm in the lower range and have the power available at the wheels to do what I need to do. If it didn't feel different and smoothly slid through the range to get there, I'm not sure I'd like that at all.

One more point on cruise control. Cruise with a CVT behave like cruise in my manual transmission vehicles. You set the speed and you stay there. In my manual, in top gear, the cruise will hold the speed steady, adding/subtracting gas pedal as it needs. With the CVT, the speed is rock steady, but the gas pedal changes are much smaller as the continously variable range is able to smooth over needed changes as the road grade changes.

In an automatic, the tranny WILL shift as you start to go up a grade and the car will slow slightly and accelerate back up to speed. I'll notice this a LOT on the highway as we're on cruise in traffic and my speed is unchanging and cars next to me are sliding forward and back as the road grade changes.

Overall, I still prefer a manual transmission. I'm still not completely sold on CVT, in large part because the feel/sounds are so different.