I have a 2001 A4 quattro with 168,000 miles. Over the summer, I had both rear bearing replaced. I live in the northeast and now when the roads are icy and snow-covered, the rear of the car fish tails like I was driving a rear wheel drive sports car. I had to do barely 25mph on the highway coming home from work in order to keep the car from fishtailing too much. It was like their was a delay in the system kicking in to keep the car in a straight line. I was being passed by old honda civics like the road was dry. What is going on? the AWD worked perfectly last winter. Did something not get replaced properly when the bearings were replaced? If anyone has any insight, I'd greatly appreciate it!
Thanks!

 

Wheel bearings should have nothing to do w/ the awd system.

What kind of tires do you have? Tread depth?

 

All tires were replaced in march-may of last year, though due to financial reasons, and tire availability, the front tires are different tread then the rear, though all tires are the exact same size, width, etc. Could that be the problem?

 

Yes - the worn tires have a slightly different diameter and that will confuse the AWD system since the wheels are rotating at different rates. I don't know if it's what is causing your problem, but if you have AWD you are always supposed to replace all four tires at once.

 

are any of the tires summer tires? like maybe the rears?

 

If there was a problem with your traction control system or stability control it would throw a light. Perhaps your hitting the gas to hard and making the tires spin. Try taking your for off the gas in the ice!

 

If the front and rear tires are different it most definitely will affect the awd system. Even If the tire size is the same tread pattern could make the different enough that they are spinning at slightly different speeds.

 

yah, the tires are the same size but the tread pattern is vastly different and the rear tires are more aggressive then the front two. I will replace the front tires with the same as the rear and see what happens. Thanks!