Need some help guys.

For the past month I've been hearing a grinding noise coming from the rear of the car. It sounds like metal rubbing/slight grinding, only audible when the car is coasting forward or in reverse. I assumed it was my rotors or pads shot, so two weeks ago I replaced both of them. The noise didnt go away. Since then, I've replaced both the rear wheel bearings. Noise didnt go away.

My calipers look pretty rusted back there, is it possible that the pistons are stuck and its causing the grinding?

Or is it possible that my rear differential sprung a leak and now I'm grinding it down possible causing permanent damage? How can I check the fluid level of it, or check for leaks. So far I've only found this thread on Audiworld: http://www.audiworld.com/tech/misc33.shtml.

Any advice you guys can give me would be greatly appreciated. It sounds likemetal grinding when I'm moving forward but NOT pressing the gas. It's not audible when the gas is pressed. Also, at low speeds under throttle it sounds like a circular noise, woosh woosh woosh as the wheel spins.

Oh, and its a 2001 1.8 with the tiptronic, 87,000 miles.

 

hello? no help because im a noob or what?

 

Have the rear diff fluid changed. Thanks for being so descriptive and sorry your post got missed.

 

How much will Audi charge me to do this? Its a bit past my level mechanically and I cant find ANY damn independant shops in the Kansas City area who know Audis...

 

Dont have Audi do it. Any shop is capable. They will check for leaks of course which could be part of the problem. Audi will charge you wayyyyyyyyyyyyyyyyyyyyyyy too much for such a simple job. Make sure they use the correct type of fluid too, i dont know what it is though.

 

According to the Bentley service manual, it takes 2.01 quarts of SAE 75W90 synthetic gear oil (the Audi part number is G052145S2).
Heavy gear oil like that gets pretty sticky when it's spilling down metal parts, so if you had a leak you'd see wet areas on your differential - the most likely spots being either inner half-shaft seal or the seal around the driveshaft flange on the front of the differential.
I doubt if the pistons in the calipers are stuck - to be stuck hard enough to make the brakes grind, you'd notice wear or bluing on your new rotors and probably feel the brakes dragging.

 

Incredible 1st post man... Welcome!

 

Ok thanks guys Ill have the fluid changed on Saturday.

Sure hope this stops the slight grinding noise. It's nothing drastic and you cant hear it unless you are in the car, coasting slowly, with the air and radio off.

 

Don't feel bad that you didn't get much replies. Its probably cause most members don't know the answer or not sure what directions to give you since that typeof problem don'treoccur as often for the members here.