fignewton

<center><img src="http://pictureposter.audiworld.com/31296/front_brake.jpg"></center><p>remember, the constant clunking going over small bumps, driving me crazy over the washboard county roads I play/commute on?
Culprit = brake calipers
Last fall, I was starting to get really bugged by this, and I got energetic and did a lot of maintenance things at about 75K miles. I changed the front bushings/bearings, did ECS slotted plated rotors front and rear, and Hawk HPS pads, ECS stainless lines, and after reading about them on the brake forum, decided to go with the Tyrolsport bushing set. These bushings replace the rubber bushings that press into the calipers, that the pins (7 on pic) go through that the caliper floats on. You press out the old rubber ones, put the new ones in, and they're secured with circlips. Grease the pins and put it back together. (and re=grease every oil change for good measure).
Anyhow, clunking didn't go away. Several times, got out, rechecked everythg, tightened everything I could find, changed the front sway bar bushings to Powerflex, replaced the sway bar end links, etc. nothing made a difference. Suspected brakes sometimes, since it sounded like it was coming from the wheel wells, but just couldn't find the source of the noise.
fast forward to 2 weeks ago, when I installed the StopTech kit. Noted IMMEDIATELY that no clunking on front end. Drove for 2 weeks, sure that it would come back again, but nope, still excellent!
Yesterday, had the stock calipers on the workbench waiting to be put away, and thought I'd pull the Tyrolsport bushings back out and the lines off, and reconfigure to stock. With the pins still in and torqued, I noted that i could easily move the calipers on the pins, barely perceptible to the eye, and they made a big "clunk" noise. What's this??? Got checking, and yes, the bushings fit in the caliper carriers loosely enough that the whole thing would move and make the noise, literally rattling around on top of the rotor. I think it would move enough to make the noise even if the pads and rotors were in place.
So, I won't say that the Tyrolsport "caused" the noise, but I could tell that it all fit back together much more tightly with the rubber bushings back in the calipers. Ideally, the TS bushings are supposed to eliminate any flex in the bushings, giving a firmer pedal and reducing the offset wear on inside/outside pads. Since I was hearing the noise some before, but not as bad, I wonder if the rubber bushings had worn over time to where the caliper could bounce over the small bumps and make the clunking. Given the wear and heat cycles they go through, it's entirely possible.
If you're having this problem, you may want to try replacing these caliper bushings, which is not hard and you can do without disconnecting the brake line and having to bleed.
hope this info helps someone else.
Fig

blackfnTTruck

Glad you got it all fixed up, that's one to remember.

TTGram

Nice trouble shooting, Thanks.

RoberTT-WWCD

for over a year and many miles in the twisties with no problems. Could have been a bad set?

Anyways, glad you found the problem.

fignewton

will see what they say. I would not have suspected this to be a problem.
fig

SereniTTy

a stoptech kit. Whoa was that a nice pedal feel...

fignewton

But there was an improvement in firmness of pedal. The StopTechs are about "perfect" and rank up there with the brakes on the 2004 996 twin turbo and new M5 I drove. Soooo easy to modulate, so much stopping power without much pedal travel, and perfectly linear.
fig

beatitt

That if you grab the old sway bar end links you replaced, you would find some play in one of the joints. I had the exact same type of low speed clunking. It took a while to figure out, but there should be ZERO play in those joints. When I put my Konis on I had everything apart, and it was only then did I discover the problem. I lived with the clunking for about a year, everything was tight and I had pretty much gave up trying to find it. I would suspect that's where the noise was coming from.

RoberTT-WWCD

Hawk HP Plus pads up front. Much better feel than stock but no where as good as BBK. The little single piston caliper can't dissipate the heat and equal the load as a 4 piston. The stocks do get a little spungy after several repeat stops in the twisties.

Hope this helps.

fignewton

Nothing I did helped until after removing the stock calipers.
fig