beebopbogo

1996 Audi A6 Quatro Wagon, automatic transmission. After replacing the half-shaft, I now have shifting and braking problems.



Basically, my right/front wheel was making a nasty, metallic grinding/clicking noise and the CV boot was torn. So I bought a replacement shaft on-line, but with no tools or space to change it out myself (plus my inherent laziness), I brought it to the shop.

He replaced the half-shaft per my request and also changed out the right/front wheel bearing. He said on the test drive it felt like that was shot, too. All told, $400 labor/parts plus the half-shaft I bought on-line.

Now my car is having troubles. Rough shifting, going into what I assume is limp mode, ABS warning light illuminated, and the Brake warning light illuminated. Could the shifting issues really be related to the repair?



Here are details if you're interested:
The cause and initial issues: I had a bit too much fun turning around in the dirt parking lot and hit a big pot-hole, "bah-BAM!" Heard some loud grinding, crunching, and clicking mechanical noise from the right front. Upon further investigation from the exterior: torn cv boot. Towed home. When I had time a week later, I drove under 5mph 2 blocks to the shop with new half-shaft in hand. I figured driving on the broken CV joint could only affect the already-broken CV joint and nothing else.

The "fix": At the shop, they said the pinch bolt had at some point been over-tightened (I assume before I bought the car 5 years ago). They also said the wheel bearing would have to be replaced, from the sounds of the test-drive.
After the work was completed, the noise was gone, driving felt good, so it felt like the problem was solved. Except upon the first touch of the brakes, something felt weird.

The brake issue: The ABS was stuttering my braking as if I were skidding, even though I was slowly gliding to a stop from 5mph in the parking lot. After a few second of pressure, the brake pedal would give a little bit and I could continue braking normally. When releasing the brake and reapplying pressure, the ABS would kick in for another 4 seconds or so before relinquishing control back to me again. A bit scary, since the braking wouldn't be as powerful as normal. After driving for about 1 minute, the ABS Warning and Brake Warning lights would illuminate and braking would feel normal again.
Also, after shutting down the car and restarting, this cycle would repeat. 1 minutes of weird braking, followed by the warning lights illuminating and the braking feeling normal again.

The shifting issue: While driving from the shop, I also noticed rough shifting. Not all shifts were smooth, but it seems the roughest were mostly shifting from 3rd to 2nd while braking. While accelerating, no real issues, but once in a while, maybe one in five up-shifts, I would feel a good jerk. That's just during normal driving.
I also noticed a change while gliding down my hill in neutral. I have a good 5 miles of downhill on my commute and tend to skip to neutral. It's the perfect grade for it. Then I would match the revs and slip back into Drive. Smooth. Now, however, it jerks hard enough to feel like I'm going to break something when I slip back into Drive.
And finally, one more weird shifting issue. This only happened twice, but while driving up the long hill the car would not shift from second into third. I released the gas pedal and it didn't shift down like normal. So I sped up to see how far it would go before shifting. I got up to almost red-line before I backed off. It was stuck in 2nd. So I stopped, it shifting into 1st, then I shut down and rebooted-- er, restarted the car. Back to normal shifting. The second time this happened, the car was stuck in 3rd. I tried moving the shift lever from Drive to 3rd, no change (as expected), then slowed down and moved the lever to 2nd. It shifted to 2nd, but even though the resulting rpms were only 3000, the shift was very rough with a large jerk.

Whew! Big post. Sorry, but thanks for the help.

upallnight

Sound more like a mess up abs sensor. Did they pull the ABS sensor before replacing the half shaft and wheel bearing? If not they could damaged the sensor. Get a scanner and scan the ECU for trouble code. A damaged ABS sensor should show up as a trouble code. When the ABS light is on the ABS system is disable so the light is there to inform you that the system is disable. Braking without ABS sounds normal.

As for the rough shifting, I would check to see if the ATF is low. There is a procedure for checking this. The car has to be level and the trans fluid temp has to be below 30C, so jack up the car the night before on four jack stands and start the engine up the next day (engine has to be running while the level is checked) and open up the fill plug to the trans. If ATF oil is oozing out you are fine, but if nothing ooze out you are low.

If you don't have a scanner for our cars, I have a Memoscan scanner for VAG cars for sale for $65.00 shipped.