Brakes squeling and clonking noises (Dave_Lewis pls read)

[mightymouse]

hi Dave Lewis,

just wanted to know how you fixed the squealing brakes? in another thread someone said something about adding copper grease which i remember Ian did. the squealing only happens when i brake hard once and then it will continue to squeal everytime i touch the brakes until it cools down? by driving without using the brakes for a while.

Also i am not sure if its the calipers but i often hear clonking noise coming from the brakes when i brake hard at slow speeds (not really hard) when parking. not sure what are the causes.

i just had all 4 shocks replaced, front and rear brake pads and front discs cuz they were quite worn.

sorry for the hijack

 

[Dieselman]

You probably nee to fit anti squeal shims as well as greasing the pads.

Squeal is caused by the pad material having harmonic resonance with the brake disk when in use. The grease dampens the vibration.
Another method is to chamfer the lead edge of the pad, but they probably are already.

How long have the pads been on, because they can bed in and stop squealing sometimes?

 

[Number_Cruncher]

The causes and cures for brake squeal are extremely complex. There have been many PhD theses written on the subject, dating back over at least the last 40 years!

In some cases, stripping and re-assembling the brake with *no* modifications will cure the squeal. Sometimes, the use of copper grease as described can cure the squeal. Sometimes the chamfering of the leading edge of the pad can cure the squeal. There are a long list of further cures and remedies which reputedly can cure the squeal.

If there were a silver bullet solution to brake squeal (and for that matter, clutch judder), all car manufacturers would implement it tomorrow, and pay you a healthy consultancy fee!

One thing to be happy about is that, providing a simple commonsense check shows that the brake pads are OK, the pistons aren't sticking, and the discs are OK, a squealing brake tends to be an efficient brake, squeal does not indicate a poor brake, squeal's just an annoyance!

 

[mightymouse]

actually they've just been put for less than a month. virtually brand new

 

[BlackC55]

Cheapie discs and pads don't help either.

 

[mightymouse]

any idea of the clonking noise? it only happens when i press the brakes. it was sunny yesterday here so i had the windows down. couple of times when i stepped on the brakes i heard the clonking too. but at higher speeds its softer or maybe its the noise from the traffic and dampens it.

 

[Dieselman]

If it's just one clonk it's possibly the pads rocking in the caliper on initial application, otherwise ball joint, loose caliper, etc.

 

[BlackC55]

One clonk in D and then another in R, it will be the pads rocking.

Edit~ I should read all posts first

 

[Dave Lewis]

Mightymouse, to de-squeal and de-clonk my front brakes (200 miles on new discs and pads), I stripped out the pads, separated the (floating) calipers, lubricated the two pins that the caliper halves slide on with copperslip (there's a tiny rubber boot to prevent grease getting out), thoroughly cleaned all the brake dust away, and stuck it all back together, with copperslip on the backs of the pads. The clonking was the play in the caliper guide pins caused by dryness and corrosion. This is on a "96 w124 E280.

 

[bolide]

Replacing aftermarket pads with MB pads cures some brake squeaks

Nick Froome
www.w124.co.uk

 

[c240yaz]

I agree with all of the above. It is an acoustics problem. You would need a laboratory of occiliscopes to find out the actual cause of the sound. The squeel has no effect in braking power.

Copper grease is the most common cure, but not on al cases.

 

[mightymouse]

i guessed the calipers because it only happens when i step on the brakes. yes it happens in D and in R. Before it was just from one clonk but now (after i had all front and rear brakes changed) if I listened carefully its on more than one. of course the front ones are more audible than the rears. at least i am hearing a lot more clonking than i did before.

would this affect the car in any way? the brakes are fine. i tried it out a lot after reading here. just when its hot it would squeal like a pig getting slaughtered. can i wait it out or shall i change them?

by the way thank you very much for all who have contributed very much appreciated