Thump in right front wheel when applying brakes

10

Asked by Jul 28, 2009 at 11:02 AM

Question type: Maintenance & Repair

Brake pad and rotors are good, almost new.  When I apply the brakes I hear and feel a thump in the right front wheel.  Could it be a bad caliper or something else?  Thanks in advance for you advice.

10 Answers

1,945

It can be a number of things. If it is a single thump, it can be one of the following. Brake pads shifting within the caliper caused by poor fitting or missing of the retaining clips (circular thingy behind each brake pad). The caliper may also shift within its holder - check slider pins(2) (quite often cross threaded) and their bushings (maybe worn out or missing). However, even more likely is worn suspension bushings, these can go as early as 40-60k miles (or after hitting potholes) but tends to be very subtle initially but progressively worse over time. If the thumps are cyclical, then it is either brake rotor defects (happened to 2 sets of oem Balo rotors on my e38, but never Brembo or Zimmerman) or uneven bedding of brake pads (google "brake pad bedding instructions" to find solution). Good luck fixing it, is worth it (I keep telling myself

2 out of 2 people think this is helpful.
10

Thanks for the response Vince. It's my daughter's car and I'm lucky enough to get to fix what I can for her. I like all your ideas and will check them all out. It's only an initial thump when applying the brake. It's not a warped rotor problem. I'll check your ideas on the calibers and I like the thought about suspension bearing. How's the best way to check those bearings? Thanks again, Ray

1,945

To check front suspension bushings, raise front end (both corners so sway bar is relaxed) up onto jack stands. Wiggle wheel (should provide enough leverage) side/side, up/down to test for plays in the thrust and traction (if so equipped) arm bushings, respectively. The thrust arm bushing is huge and you should be able to see tears in the rubber. This test should also make any tie rod ends wear noticeable.

1 out of 1 people think this is helpful.
10

Thanks Vince, That was very informative. I get the car next week to play with and will check all then. I see you have no Fans on your profile. If I could figure out how to become a fan of yours I'd sigh up. Well anyway Thanks again and I'll let you know what I find next week.

10

Hi Vince, I found the problem. Just as you said, Front control arm bushings. Replaced both sides. $ 189.00 from BMW. Oh well, It's done and I feel better about my daughter driving it. Thanks again for your help, Ray

1 out of 1 people think this is helpful.
5

I just replaced the upper and lower control arms on my 735i and it got rid of most of the bumping while braking. I still get a little bit...but not anywhere as bad...I am looking into replacing the sway bar.

10

Hi Chris, Let me know how you make out with that sway bar. My daughter says she still has a slight thump when she initially applies the brake. I replaced the large bushings that have a casting around them. Are there any other bushings that need to be replaced on the lower control arm? Thanks, Ray

25

What model do you have? It very well could be lower control arm bushings. When they wear out you mat hear a thumping noise on brakeing.

10

Thanks Colin, The car is a 2005 325i. I replaced the lower control arm bushing but stil get a slight click when I initially step on brake. It sounds like it could be brake pads. Vince 324 also mentioned shims on brake pads. I don't remember shims being included in the new pad I put on. I wonder if the shims are sold separately?

5

did you replace the lower and upper control arms?

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