AWD unbalanced wheels jittery shifting


#1

Can one or more unbalanced wheels give the impression of jittery transmission shifting or outright affect the shifting on an automatic, awd vehicle?

I have a 1999 Audi A6 Avant with a set of four new Bridgestone Potenza, all season tires and the car shudders between 3rd and 4th and 4th and 5th, or if you take your foot of the pedal and put it back on again.

I understand this could also be a sign of troubles with the locking torque convertor.


#2

If the tires are new and you suspect a balance problem, take it back and have them re-balance the tires. A reputable dealer will do it at no additional cost. Once in a while, even a good shop can make a mistake.

With that out of the way, if the problem still exists, I highly recommend that you have the transmission flushed, conditioned and re-filled. You will need to shop around for a place that is intimate with the process for Audi and VW. There is a special process for flush & fill and not everyone has the equipment or the mentality to do it. You can go to a dealer but many times they will tell you that the transmissions are sealed for life and must not be touched. I just had mine done at a local import shop for around $200. The synthetic fluid is not cheap. It shifts like brand new again. If you have never had it done, you are probably due.


#3

Tires will not cause the symptoms you describe.

Sorry, but it’s the tranny!


#4

Thanks for the response. I did some looking around. The dealership said just what you thought they would, that the transmissions are sealed, it was the torque converter, and that I’d need a new/remanufactured transmission, for the low-low price of $5300.00.
I got some recommendations for reputable transmission shops in the area, and took the car to a place called Park Auto. The technician took the car out with all his diagnostic equipment on it and told me the transmission and the locking torque converter in particular were working just fine; that the shuddering was in all likelihood because the so-called life-time transmission fluid was all gummed up and hardened. For $500.00, he drained, flushed, and refilled the transmission; drove the car; then drain, flushed, changed the filter, and refilled the transmission a second time. After a few days of driving, the shuddering was barely noticeable. After a week, it only occurs once and awhile. The technician suggests that as the new fluid displaces the old stuff that had impregnated the disk surfaces, any shuddering will probably go away altogether. In any case, he said that there is definitely no need to replace the transmission.