Don's S6

Hello and thanks for helping. I just had my pads and discs on my S6 changed by my reliable audi mechanic. When doing a left side turn, the left side front brakes make a horrible grinding noise. He's at a loss and does not understand what seems to be the problem. He changed the pads a second time and made sure everything was installed properly but the problem persists, but now intermittently. Please send in your suggestions. Thanks, Don

jcman

Is your mechanic absolutely positive that the replacement rotors are the right one's?
321mm rotors cover PR codes 1LG,1LA, 1LX and T7Z unless you have 1LT or 1LF which would be a 312mm rotor and this I'd doubt on a S6 Avant.

Don's S6

Yes he double checked on my second visit to make sure he had the right parts. They are the 321mm.

SloopJohnB@mac.com

I thought I had posted this earlier.
How about a rotor that was put on with a piece of crap between the rotor and the hub, making the rotor hit the backing plate. Check for rotor run out…most people don't check runout with a dial indicator when they change rotors.

Is there shiny metal on the rotor so you can see where the grinding noise is coming from? If it's a new rotor you may have to color it with a blue magic marker or preferably dye-chem (a blue machinist's marking dye) on the outer edges…don't put it on the friction surfaces.

Correct accordingly.

MP4.2+6.0

Make sure one of front wheel bearing bolts aren't backing out. Had this suddenly on my prior 2000 A6 4.2. Dealer had replaced bearing under 4/50 warranty previously, but obviously not such a great job with the bolts or LockTite. If you jack up wheel, spin it and hear a grinding noise and it isn't the pads, think about those bolts and look for metal shavings on the inside of the hub area right at the slight gap with the outer CV joint.

Watch out on the 4.2/S6 rotors too--there are two rotor hat offsets. One found with 4.2's of various flavors and another with the 2.7T. I would think you couldn't even fit the caliper though if you have the wrong rotor offset.

Don's S6

Thanks for your tips everyone. Rotors were double checked, backing plates also, pads, suspension, joints and bearings were checked. We just decided to change the pads and put better quality ones on. At the beginning of the test drive the noise had stopped. After driving about 10 mins on the highway, the first left turn after I took the exit the grinding noise appeared again!!! But it then stopped again...So now it looks like when I make an easy left turn all is quiet, but when I make a sharp left, the grinding noise starts and then stops after I have finished my turn. Even more frustrating, it is now an intermittent problem...Maybe I should just stop turning left?

Just Me

sounds like your wheel bearing has play and allows htings to move under load. Either that or the dust/rock shield bends slightly and touches something. Neither is the end of the world.

Grant

jcman

The only part that keeps the axle and what follows true "in line" is the wheel bearing, something is moving off plane.