I have a 2001 a4 2.8 and there is an odd noise coming from the driver side rear wheel area. It starts making the noise around 20 mph and makes the noise until around 40 mph. I'm 90% sure that it doesn't have anything to do with the brakes and I think it may have to do with the rear differential. Any Ideas?

 

What does the noise sound like?

 

Kind of a lower pitch squeal. Not like a higher squeal like the brakes make. Its seriously hard to describe.

 

Could be... while its making noise, do a couple of left/right turns. If it goes away turning left, but louder turning right, it could be the left wheel bearing. Same when turning right - right bearing.

If its the diff, you should be able to make it slip (clunking) while turning under power.