S8_Serge

Just wanted to share my experience with the annoying squeaky brakes on my '01 S8. It's been posted by many: faint whining squeal after miles of driving at speeds over 50 mph coming from the front. Slightly turning the wheel can stop it, or worsen it. When applying the brakes it increases in intensity and then drops off. The local Audi dealer told me that it's probably the pads riding on the ridges at the in and outside perimeter of the rotors. He wasn't willing to do anything about it because Audi_USA's warranty doesn't cover brake noises. He could turn the rotors down for $280. A local shop came up with the same diagnosis and turned the rotors for $80. For the last 400 miles the sound has been gone. No guarantee that it will last (those ridges will built up again as the rotor wears), but at least the diagnosis seems to be correct.

BTW I noticed that the rotors have flat notches on the outside diameter (where the cooling vents are). The brake-guy said that it is for balancing. Is that correct or is there another explanation?

JimR

Had this ridge built up on this set of pads (i.e. pads new, rotors new or newly turned), or had you changed pads without turning the rotors?

ryoung

The Brembos use a radial mount, where the mounting bolts are parallel to the wheel's spokes. To totally eliminate the possibility of ridges ever building up on the perimeter of the rotor, install a spacer washer(s) on the big M14 socket head cap screw between the caliper and upright.

I can't tell you how much you need to move the caliper. With my Alcon's, I moved the caliper pads very very slightly past the OD of the rotor, just enough so that the pad can barely catch a fingernail. If you move the caliper too far out, you'll build up ridges on the pads instead of the rotor (though these would probably break off when the rotor heats up and expands radially).

S8: #7 are the M14x1.5x38 socket head cap screws

<img src="http://www.audipages.com/Tech_Articles/susp_whls_brake_steer/S8brake4.gif">

The A8's caliper uses an axial mount, with mounting bolts parallel to the axle ... no adjustment possible.

<img src="http://www.audipages.com/Tech_Articles/susp_whls_brake_steer/frbrakes2.GIF">

S8_Serge

I've only had this car for one year and don't know it's full prior 40k-miles history. I'd assume no matter what the combination of pads and rotors, eventually that ridge builds up again and only Randy Young's proposed solution will really give the definitive solution.

Serge

garibaldi

Next time another way to stop that noise, is to pull the pads, and chamfer the inner and outer edges of the pads near the ridge so that there is no material dragging on the ridge. I had the exact same noise on my car and did that and it cured it, I eventually just put on a new set of rotors and pads.