540 brake thumping - BMW Forum

540bemerdude · 05-21-2006, 10:42 AM

I just replace the struts, rotors and pads on the front. Had to use C clamp type vise grip to push caliper piston back in for new pads, like normal. Now when I apply the brakes I get a rotational thumping noise from both front wheels, like there is something on the rotor. I check and everything seems fine. Could the noise be caused by the ABS system?

540bemerdude · 05-22-2006, 06:04 PM

After driving the car today it sure sounds like the thumping is coming from under the hood, so it does appear to be coming from the ABS system. It does get louder the harder you press on the brake pedal.
Anybody out there ever hear of something like this. Any help would be appreciated. BTW the car is a 1995 model.

16valex · 05-23-2006, 06:50 AM

Unless your rotors are already warped, did you take it real easy after you replace them, depends who are the manufactures of the rotors the quality is not the same, Some people went out of their ways to bedding the new rotor and pads, I usually just take it real easy.

One other thing that you can do is to go back and make sure there's no debris caught in between the rotor and pad, make sure the pad clips are installed correctly, the calibur bolts are properly torque.

Good luck
Alex

540bemerdude · 05-23-2006, 07:53 AM

Yes, everything is clean and tight. I used new Brembo rotors and degreased with lots of brake clean. The noise happened when I backed it out of the garage to test drive it. I was easy on the brake in too.....go figure...

LOS · 05-23-2006, 09:59 AM

I think your problem is the struts. Make sure every bolt & nut is tight to it's proper torque. I'm sure something is loose down there.

For example, I had my upper arm bushings replaced two years ago and the mechanic left a couple of nuts loose and created a thump noise that you described. It only happened when braking or going over bumps. Anyway, we found the problem the following day.

LOS