formerly dennisA4

So it's the calm before the storm. For the past few days I've had an A4 loaner from my dealer until my A3 gets here next week. The A4 is a base 2007 2.0T CVT. I noticed that it has a subtle choppy/jerky feeling when taking off from a stop. It's hard to take off slow and smooth and acceleration feels a little rough. It's not major but I can feel it. Anyway, it got me thinking... what the heck is the difference between the two transmissions? Once moving, both shift very smooth. And is the jerkiness i'm feeling inherent to the cvt only, both or maybe something wrong with just this one sample?

Can someone explain the difference to me in "dumbass" terms? I have no idea how either one works. All i know is dsg has 2 clutches and there are paddle shifters.

MikeSS

<a href="http://cars.about.com/od/thingsyouneedtoknow/a/CVT.htm">How CVT works #1</a>

<a href="http://auto.howstuffworks.com/cvt.htm">How CVT works #2</a>

absoluTT A3

IMHO, it's a great transmission for people who drive cars merely for going from point A to point B, as they are more efficient than your standard automatic.

<u>Here is what Wikipedia says:</u>
The continuously variable transmission (CVT) is a transmission in which the ratio of the rotational speeds of two shafts, as the input shaft and output shaft of a vehicle or other machine, can be varied continuously within a given range, providing an infinite number of possible ratios.

The continuously variable transmission should not be confused with the power split transmission (PST), as used in the Toyota Prius and other hybrid vehicles that use two or more inputs with one output, despite some similarities in their function.

A CVT need not be automatic, nor include zero or reverse output. Such features may be adapted to CVTs in certain specific applications.

Other mechanical transmissions only allow a few different discrete gear ratios to be selected, but the continuously variable transmission essentially has an infinite number of ratios available within a finite range, so it enables the relationship between the speed of a vehicle, engine, and the driven speed of the wheels to be selected within a continuous range. This can provide better fuel economy than other transmissions by enabling the engine to run at its most efficient speeds within a narrow range.<ul><li><a href="http://en.wikipedia.org/wiki/Continuously_variable_transmission">Wikipedia - CVT</a></li></ul>

April

you stop, start, or go into reverse.

People have often commented about the clutch either having a slight delay or being jerky in a creep, as it does not allow for much slip. So treat it a bit like an E-Gear/R-Tronic/F1 style unit, and not an auto. There seem to be ongoing software updates that are looking for the ideal level of slip while keeping wear down.

Acceleration should be smooth other than if the engine has vibrations at certain revs.

SpeedTriple

It has chains connecting two adjustable gears that can change their diameters by widening or narrowing. The continuously variable gear ratios helps the engine run at optimum efficiency. Engines are most efficient at full throttle and low RPMs, and the CVT can keep it that way much better than conventional automatics. The drawback is that too much torque can make the chain slip.