Thumping sound when applying brakes W124

[Mark Wheeler]

I have a 1991 estate that is making a curious thump when braking. It started a couple of weeks ago and that day it happened every time I pressed the brake pedal, it was worse when feathering rather than firm pressure. It was as if one of the pins had come out of the pad, so put it in my local garage a couple of days later for repair as it was booked in for full service anyway. By then the problem had disappeared. The garage could find nothing, surprise surprise, now it's back.
The noise is coming from the nearside, oh and a couple of times it has happened not whilst applying but when releasing pressure on the pedal.

Has anyone had this problem and able to help pinpoint the cause.
Any help would be appreciated, yours in anticipation.

Mark Wheeler

 

[television]

You either have a warped disc on the front, or one of the rear disc is cracking or splitting. If it is worse after a hard stop it will be the front.
It is easy to change them, and they are not expensive.
Malcolm


You are in the wrong section, it should have been placed in the brakes section

 

[mike65]

Never heard a 'thumping' from a dodgy disc, its more a hollow scrape in my expeirence. Still you might be right but it sounds more like something to do with steering/suspension, under braking stress may be acting on a worn ball joint for example.

Mike.

 

[television]

Never heard a 'thumping' from a dodgy disc, its more a hollow scrape in my expeirence. Still you might be right but it sounds more like something to do with steering/suspension, under braking stress may be acting on a worn ball joint for example.

Mike.

You can feel the faulty disc through the brake pedal, the definite clue is that you can feel it with a light tough of the brake pedal, it is a very common problem. You cant feel a worn ball joint through the pedal.

Malcolm

 

[turnipsock]

I get a rumbling vibration when I apply the brakes. I noticed it after replacing the pads (all round). I'm sure it's because the discs are near their life end and the pads need to be bedded in.

 

[davidsl500]

is it one thump or a series of thumps? if its a series of thumps do they match the wheel rotation speed?

 

[Mark Wheeler]

Thanks for the interest shown guys, I'll reply to all your comments rather than individually if you don't mind.
The front discs were renewed 3 years ago (40k miles) so I wouldn't have suspected them, but I'll quiz my garage as to how thoroughly they looked. Ball joint should have been picked up at the service, but no mention by the mechanic, but as often happens, the fault didn't occur during their test drive.

There is no rumble or judder. In fact the thump (singular) isn't felt under the pedal it seems remote, to the nearside of the vehicle. It doesn't affect the braking and whilst annoying for the driver, is unnerving for the passenger.

Fingers crossed the problem occurs whilst with the mechanic tomorrow but in the meantime, would welcome any other clues.
Mark

 

[Blobcat]

Brake pad or caliper moving?
Some Volvo's and Vauxhalls can do this with the handbrake shoes inside the rear discs if the handbrake is applied whilst car still moving. Makes one hell of a noise.

 

[malcolm E53 AMG]

Sounds very much like a suspension problem under load whilst braking.

Probably anti roll bar bushes but could be something more sinister llke a broken spring. A good inspection should reveal all.

 

[Mark Wheeler]

Problem solved.
It turns out that the brake pad lining had come away from the backing plate and every now and then the lining would reseat into it's original position causing the thumping noise, and sit happily for a period of time before moving again.

A change of pads and all appears okay.

Many thanks to Malcolm,Mike,Television,David,Turnipsock and Blobcat
for your help, hope to do the same for you guys one day.

Mark Wheeler

 

[Bolide]

Brake pads

Were they Mercedes pads or pattern parts?

Nick Froome
www.w124.co.uk