read an article about new honda CVT and then thought about the cvt popping up on a bicycle recently, claimed to be back from davinci's time. then you have the altima? and dodge was promising a cvt for the caliber at one point. since half of you f00lz are engineers, yay or nay for CVTs to come and why have they not been refined earlier (i beleive inability to cope with high power applications kept them primarily in the scooter market and some industrial applications previously)?

http://world.honda.com/Tokyo2005/dn01/ - honda
http://www.youtube.com/watch?v=kVPjhmTThPo -b

1/22/2008 9:22:04 PM

its freaky, they dont shift.

1/22/2008 9:25:55 PM

Quote :

"i beleive inability to cope with high power applications"

basically even though they would be more efficient

1/22/2008 9:40:08 PM

Quite simply, all CVTs to date rely on some sort of frictive mechanics in order to function. The big deal is slippage or belt element failure under high horsepower applications.

1/22/2008 9:54:02 PM

Hasn't this been out a while on a6's? How have those older ones held up?

1/22/2008 10:16:09 PM

been on polaris atv's for years and while they did have some early slippage issues due to water and stuff, but those were cured and several other makers adopted it.

in an automotive application i dont see why it wouldnt work for what theyre using it for. it wont be behind your cummins anytime soon tho. im sure they went through similar friction issues with regular plate clutches when they first started out.

1/22/2008 10:31:14 PM

i had an altima rental with one a few weeks ago. it was pretty neat, the first one i'd driven. in manual mode, it shifted up/down MUCH smoother than a conventional auto and was actually useful for "spirited" driving. partial throttle you could sort of feel/hear it shifting, but at wot it just stayed in a constant rpm range. good for keeping a motor in the powerband. it actually reminded me a lot of a conventional auto with a high stall converter...

i think we'll start seeing more in smaller cars. technology has improved so much in conventional autos they're nearly the same as far as efficiency, etc. goes though. i don't see them taking over,

1/22/2008 11:59:09 PM

what does it "shift" for? just to mimic a regular auto and not weird out people who don't understand how it works?

shit, i want one for my Evo...even if it can't handle the power, it would prob last as long as an Evo clutch, and prob not cost much more to fix when it shit the bed!



if it doesn't have lots of internal frictional losses (and I don't see why it would), it should be a performance asset. no time spent shifting, and you could optimize the engine by taking advantage of the ability to operate in a narrow powerband--i.e., you could achieve very high specific output and not have to worry about making power over a useable rpm range.

1/23/2008 1:50:00 AM

and yet the Subaru Justy never took off

1/23/2008 2:43:52 AM

My dad's 03 Audi A4 has a CVT.
The whole purpose is to stay in the power band longer.
If you are used to shifting, a CVT will hate you. The reflex of lifting off at a shift point really fucks with them and make quite a jerking motion.

1/23/2008 8:21:37 AM

http://auto.howstuffworks.com/cvt5.htm

1/23/2008 8:21:57 AM

i have a CVT in my a4, its just one of those thigns you get used to, i like it a lot

1/23/2008 11:23:44 AM

^^^ again, what is this in the power band LONGER?

and lifting at shift points?


does this thing artificially simulate gearchanges? if so, that's fucking stupid--the whole point is that the engine is allowed to go to its happy place and stay there.

1/23/2008 1:11:43 PM

it doesn't simulate gear changes. people who are used to regular trans' usually lift off the accelerator to shift. which causes a jerking motion. if you keep your foot planted, nothing happens except smooth accel.

cvt's are pretty awesome.

i like my manumatic auto, you never have to lift off the accel.

[Edited on January 23, 2008 at 1:43 PM. Reason : e]

1/23/2008 1:43:01 PM

any body want to comment on how good the engine braking is

that is one of the reasons that i like a true manual or smg

1/23/2008 4:19:02 PM

most engines simply don't sound good enough for you to want them to operate at constant revs. I've driven several cvt cars:

-ford five hundred (before it was a taurus)
-nissan murano
-nissan altima
-toyota prius
-audi a4 multitronic

they all are amazingly smooth and often far punchier than each car's power:weight ratio suggests while getting better mileage than each would with a conventional gearbox. But the droning.... oy. I wanted to wear earplugs after driving the murano. If chevy licensed the tech from nissan, it would be interesting on a impala SS... or maybe a cadillac deville.

the one in the altima lets you select "gears" which gives some fixed-ratio satisfaction but it cheats a little. I'm not sold on it except for applications like the prius and other vehicles where the engine is so muted that you don't care if the sound is annoying...

1/23/2008 5:06:19 PM

as far as next generation automatics go, I have to say I prefer the DSG style. They are very smooth (not as much as a CVT obviously) because of how quick it shifts and therefore the minuscule lapse in power delivery.

Every CVT ATV out there has very little response when you lift and then reapply the throttle quickly, the transmission has to "catch back up." This leads me to beleive that this type of tranny in a sports car application would be undesirable.

1/23/2008 6:45:34 PM

i've driven the caliber with CVT. my biggest complaint is the response time to "downshift" was really slow. it actually made pulling out in traffic from a stop really scary because the stupid thing wouldn't go. i realize part of it was the little 2.4L didn't have any torque, but eventually i had to learn to predict the lag. once you got it going, it felt weird to keep your foot in it from 15-60 and it never shifts, just keeps whining. at highway speeds, again it suffered in that the response time was too slow to "downshift" for passing.

all in all, i would not recommend the caliber. (i won't even go into the absolutely absurd understeer issues)

1/23/2008 7:05:27 PM

i own a mini cooper and a new jeep patriot both with cvts, they take some getting used to but the fuel milage is great and personally I'd love to see them in a diesel application, thing of how great that would work.

1/23/2008 8:06:48 PM

Quote :

"it actually made pulling out in traffic from a stop really scary because the stupid thing wouldn't go. i realize part of it was the little 2.4L didn't have any torque, but eventually i had to learn to predict the lag."

couldn't have said it better myself. That was what i was referring to when I said it takes getting used to...

1/24/2008 12:05:57 PM