Gentlemen.

Did a 4 point pad/rotor swap on a B6 Quattro this weekend. Was my first time doing a brake job on my Audi. Everything was swell and stress-free, save the 107*F temp outside.

My problem is this:
Now that I've got the new shiny bits, the passenger side rear wheel gives off an intermittent metallic rattling-rubbing-grinding-floppy-rotor-or-loose-caliper sound. When I discovered the problem, I took the point back down to the hub and reinstalled everything again, making sure everything was in line and straight. The issue still persists. I've done some reading on the subject and my only thought could be the bearing. However, the noise was definitely not there before the brake job. I did have to "convince" the rotor off, even after PB blasting it pretty extensively. That's the only thing I can think that could have impacted the bearings in the least.
However, at one point while trying to fight the 8MM hex, the caliper slipped and put a slight tug on the brake line... the line looked fine on a visual inspection, and no brake fluid has escaped from the area since. Brake fluid levels are good, but the pedal gives more than it should on new pads and rotors.

The noise is prominent at low speeds, when the brakes are NOT engaged. The emergency brake works, although... to a lesser extent than before, which is a secondary worry. The noise does not persist through use of the e-brake.

I've read everything google has to offer on the subject (and several forums). No one's issue seems linear to mine. Most issues are when the brake is applied. (Although, my noise persists through normal braking, and diminishes on harder braking.)

I've bedded the brakes from 40-10mph about 10 times. I'm in the middle of Houston on Westheimer, so I don't have an area (atm) to do a real solid 60-15mph bed.

I'd really like to get this hammered out soon, as I need to get my car inspected. The noise is driving me nuts. Any suggestions?

 

hmm you know mine and my friends car both experience this issue. both our cars rattle in the front going over bumps. if i move forward and apply brake theres clunk sound and doesn't happen again until i put it in reverse.

the rear pads were changed on mine after the fronts, and on my friend's car we did all 4. the rear on mine are almost all worn down in just under a year. my friend's car locks up the right rear.

so i have been looking around and some people say the e-brake cable needs to be adjusted. <- this would probably fix your ebrake problem.

 

Sounds like you could have seized a caliper when you pushed the piston back in to get the new pad on. After driving it around, is that rotor hot as hell? (Obviously in comparison to the other 3 rotors)

 

Had a chance to get out and do some investigation today. I have a 5 month old, so time under the car is limited. I bled the lines, again, since the pedal was a little squishy. That tightened everything up so I could really get to the bottom of it.

It does, in fact seem that the passenger rear rotor is a higher temp than the others; although, it's 99F today, so a little hard to tell. But, when I pulled the rear wheels to bleed the lines, I noticed that the point in question's rotor is less worn than the other rear (the driver's side rear's rotor has almost worn the coating off). With the concept of a seized caliper in mind, I did some tests with someone pumping and holding the brake, and releasing. I was able to run Teflon tape between the driver's side pad and rotor with the brakes disengaged without effecting the tape. However, the passenger's side rubbed the tape and left markings and tore a part of the tape. Therefore, I'm thinking that caliper is somewhat seized.

After bleeding the lines again and topping off a little more fluid - (It was 107F last weekend when I did the brake job so... I was a little out of it by the time I bled the brakes) the sound no longer occurs when the brakes are engaged, it only occurs now for a short period after the brakes are released, and then it seems the piston works its way free after about 10 rotations of the wheel.

I really don't think it's a bearing, since the wheel has no movement and the hub seems solid.

Autozone doesn't have the caliper in stock, but they're getting it from a nearby store. I'll change the caliper tomorrow and go from there.

I really appreciate the help, fellas. I'll shoot an update tomorrow.

Now to get the damn EGR to stop rattling on a cold start. =)

 

After arseing about Houston all day, I found an OEM Lucas caliper and replaced mine (thought to be seized). The noise persisted after installation of the new caliper, although braking power was increased.

There is no wheel rock, so I really don't think it's the hub. However, upon close inspection while bleeding the lines, I noticed the entire caliper and assembly rocks horizontally when the brakes are applied (about 3/4in). I ensured that the 8MM hex bolts were tightened on the caliper assembly and made sure the splash guard was tightened firmly. I'm really at a loss for what the cause of this problem is. 6 hours mucking with it today... I'm spent.

Any ideas where to start next?

 

Completely bled the brake lines today with a vacuum. Perfect pedal action.

The noise has stopped consistently through a straight course, but squeals very loudly on a RIGHT turn. LEFT turns are silent. The noise is still originating from the passenger rear point.

I took it to a brake shop today and they had no clue what it was. They suggested it was probably not bed yet. However, I've done several bedding sessions, and it's ONLY the passenger rear point. O.o I'm spent.

Could it be bearings? If the bearings were worn, wouldn't I get vibration at higher speeds? The car drives smoothly, no vibration, no pulling. I can brake without my hands on the wheel in a straight line.

Any ideas gentlemen? I'm stumped.