CVTs drivability problems


Many Audi owners complain about drivability problems with the CVT transmission specially after a repair work was performed. The transmission still not drives perfect. there are very few garages or transmission shops that are experienced with the CVTs. To many shops and people work on the CVT transmissions and don't understand the concept of it or not even have the proper tools to work on it. Servicing and rebuilding this units requires special tools.

The Maine difference between the Audi CVT-transmission and many other CVTs is, the Audi cvt have NO torque converter. CVTs without a torque converter are typically driven through a dual mass flywheel or a torsional damper plate that connects the crankshaft to the input shaft. The BMW Mini Cooper VTlF, the Audi A6/8 01J and Honda Civic CVTs are examples of this design. To prevent a stalling condition when the transmission is placed in gear or when it comes to a stop in gear, a clutch inside the transmission must release. The VTlF and 01J CVTs release the forward or reverse clutch, while the Honda Civic CVT releases a start clutch in both Drive and Reverse. These clutches are pulsed on and off very frequently and are susceptible to failure. This can cause a variety of complaints, such as chatter on takeoff, sudden slipping or neutralizing conditions, unusual idle fluctuations or a loss of hill-hold function.

Audi offers an update package that increases the forward clutch from six frictions to a seven-friction stack-up, but it must be accompanied by a computer reflash that changes pressure and apply strategies. If the reflash is not performed, the updated clutch pack will be damaged in fairly short order.

Relearn procedures are very important on CVTs that substitute a clutch inside the transmission for a torque converter. If relearn procedures are not performed after any repairs, drivability problems and transmission failures will absolutely occur. Be aware that these procedures exist and that they must be performed.

Audi not only has a clutch relearn procedure, but also a special procedure for changing the fluid. All four wheels must be off the ground a minimum of 8 in., and each wheel must be able to be rotated freely by hand. While observing the Tiptronic indicator, step-shift the CVT from its lowest ratio to its highest (six or seven speeds), accelerating moderately after each shift but never exceeding 35 mph. Shift the transmission back down to 1st gear and gently apply the brake until the wheels come to a stop. Once the wheels are stopped, place the transmission in Reverse, release the brake and moderately depress the accelerator to a Reverse gear speed of 12 mph. Once again, gently apply the brakes until the wheels come to a stop. Return the selector lever to Drive and repeat these steps five more times. When completed, place the selector lever in Park and turn the engine off. Now you can change the transmission fluid. When you're done, repeat these procedures before placing the vehicle on the ground and doing a road test.


Herbert Gruber, eurotrans