sns8tn

I was wondering if anyone has any info on the possible cause of a wheel squeak on the A8/S8 line. I have a '01 S8, about 27K mi, relatively new rotors and pads (changed due to the more common wheel squeal with brake application), and I've noted a gradually increasing high pitched wheel squeak, like metal rubbing on metal, that occurs in direct proportion to wheel rotation speed, only when the wheels have warmed up from driving for awhile. The sound briefly disappears with heavy application of the brakes, and then reappears once the pressure is let up somewhat. It initially only seemed present at certain speeds, but can now be heard at all speeds. The Audi service folks assured me that this was brake "vibration" and that a little white grease would take care of the problem. Naturally, this "explanation" and the fact that they couldn't even hear the problem on a test drive, didn't leave me with a vast degree of confidence in their diagnostic skills. I understand the brake squeal problem is from harmonic vibration of the pads during application (a design flaw if ever there was one). The squeak seems more likely due to metal contacting metal in an unanticipated and unwanted fashion. I'd love some insight into the problem so that I can point my local diagnosticians in the proper direction the next time I go in for service (had to take them the Audi Tech. bulletin on the squeal problem before, on the fourth attempt, they managed to "isolate the problem" and fixed it with the rotor/pad change, plus pad prep).

[sorry for the wordy post, TIA for any insight you may have].

Maxster4.2

I had the same problem on my 4.2 and they never gave me a satisfactory answer.

I explained to the Svc Mgr that the car never had that problem when new but now that they worked on the breaks they can't reslove the issue.

PaulW

Over the past year or two that I've been around here, a lot of people report this problem specifically to S8's. I take it that you are reporting normal brake squeal at medium brake pressures.

<a href="https://forums.audiworld.com/a8/msgs/20690.phtml">I had similiar problems</a> before I did my brake upgrade. I went back to stock pads and rotors and found everything was great again.

I don't know what size the pads are on the S8 calipers, but there has to be a million pad suppliers out there. If you are driving on the street and don't want brake squeal (isn't that embarassing?).....I might suggest investigating if a stock Porsche compound pad would fit in your Brembo caliper.

I have stock Porsche 996tt pads for street use (front) and stock Audi pads for the rear. I'm using Porsch 993tt rotors.

My brakes DO NOT squeal a bit around town....oh it's wonderful.

Does anybody know what size the S8 front pad is and if it is compatible with another OEM Porsch pad?

<img src="http://www.audipages.com/upgrades/bira6.JPG">

Paul<ul><li><a href="https://forums.audiworld.com/a8/msgs/20690.phtml">My brake squeal problems</a></li></ul>

sns8tn

Actually, no, I'm not referring to brake squeal which I did have and has been fixed. This is truly a high pitched metal rubbing on metal squeaking sound, like the sound of the wheel scraping past something as it rotates (which likely accounts for the sound's changes with wheel rotation speed).

As I noted earlier, the Audi service folks explained this was a "vibration" problem, but vibrations shouldn't yield a scraping squeaky type sound.

Kris K

ryoung

Is the CV boot still intact? Does the pitch of the squeak change during cornering? I've never had the problem, but it sounds like it could be a dry bearing somewhere.

Did the dealer happen say where "a little white grease" is supposed to go or does he expect you to figure it out :-(

PaulW

I don't know if you have a metal shield on the back side of the rotor, but if you do, that's the first place I would be looking.

Here's a picture of the S8 brake system, see the shield on the back side of the rotor? Many times duirng a brake job these shields get pushed into the rotor and will cause exactly the noise you are describing.

Jack up the car, rotate the front wheels (you will need to put it on jack stands to do this) and you'll find which one is making the noise. Take the wheel off and pull the shield away. Hopefully this is your problem.

<img src="http://www.audipages.com/Tech_Articles/susp_whls_brake_steer/S8caliper.JPG">

ryoung

they've been gone for over two years. And this year I "lost" the dust shields for the rear rotors when I noticed that the inside pads ran MUCH hotter than the outside pads.

sns8tn

The service people didn't tell me where they were putting the white grease. Allegedly, though, they did apply it even though they couldn't hear the problem. I'd considered a bearing problem, but it wouldn't make sense that this would only be heard once the wheel heats up from driving would it? The brake shield, however, could cause the problem if there is no contact when cold and minimal contact once heat expansion occurs. I guess I'll get the jacks out this weekend and take a look.

Dave G

I had the identical problem (on a non-Audi vehicle), and it was the wheel bearing.