squeaky brakes w202

[merclover79]

i have a w202 estate 250td that needed rear pads changed, i changed them with genuine merc parts and after about ten miles there was a really bad squeak when braking. i have re fitted them with loads of anti squeel grease and even tried another make of brake pads but the noise is still there.

i heard a very similar noise the other day when out walking and turned round to see another w202 braking with the same noise.

i have been a mechanic for about 15 years and have never had this problem before on any car is this a common problem?

any help will be greatfully recieved.:-?

 

[television]

Its often just the glaze on the disc, and it will go away after a few miles once the have bedded in all over

 

[merclover79]

noisy brakes

ive prob done about 400 miles and the noise is no better.

 

[television]

This is in this months trade press

 

[merclover79]

think i'll try discs then. thank you for your help.

 

[philharve]

Squealing brakes is abnormal

Hi merclover79

I had new discs & pads fitted about 3 weeks ago on my 202 and they have never squealed. Squealing is abnormal and, as Malcolm points out, the cause is often elsewhere.

REGARDS

Phil

 

[television]

Perhaps I can explain what squeaking is caused by.

Squeaking is caused by resonance, that is when one surface is skidding on the other, in this case the pads are skidding on the disc surface in the same way as a bowed musical instrument. The pad is resonating to the surface of the disc, normally owing to the glazing or the lip on the disc. One can sand and rough up the glazed surface, the outside face is easy but often very hard to do the inside. the grease absorbs some of the play in the pad, and this has a damping effect reducing or nulling the resonance. Once the pad has bedded in, then the noise goes away. Often the face of the pad is not parallel to the disc, and this can be seen if you mist coat the disc with a spray paint. I fitted new disc to my car using pads that were 2k miles old, and it took 800 miles for the pads to clean up the whole braking surface on the disc, once bedded in you have full braking and not before, and they squeaked for the first 100 miles.