2006 A8L Brake knock/squeak when NOT on pedal
 

New to forum and Audi. 2006 A8L w/103,000. Pads and rotors were done 12 months/6,000 miles ago. About 9 months ago I noticed some squeaking from the front-left wheel at low speed (0-30), which went away as soon as brakes were applied. A few months later I noticed a rattle when going over potholes/rough spots also from the front left as well as an occasional knocking sound. If I applied the brakes in mid-rattle or while knocking, sound immediately disappeared.

My mechanic (Audi/VW guy) explained there is some sort of goop used to keep the pads on calipers when the brake is released and they pull away and it was likely this had come loose. Yesterday they re-did the goop and inspected the pads, which were still okay. Squeak, knock and rattle were gone but returned after 30 miles or so. Now the noises are constant UNLESS I press on the brakes at which point they disappear.

We're stumped...any ideas?

Has he checked for any foreign objects in the dust shield?

Were the brakes properly put back together? No loose parts and nothing missing?

I need a Audi mechanic in NYC or westchester county

Took it to another mechanic who sorted out the problem. Turns out only the pads had been done last year and they used some unidentifiable generic brand that didn't fit well. They also bypassed the pad sensors on the front and did not include anti-rattle clips. The front rotors were also slightly warped causing some mild pulsing.

They turned the front rotors and replaced all the pads with OEM. Having never driven the car without crappy pads and warped rotors, I'm amazed at how much better the brakes feel. Problem solved!