Warm weather windows down, I hear horrible brake squeal at say 5mph!

[Submariner1]

never heard this with the window up. But with the windows down.
I get intrusive brake squeal at about 5mph.

Going fast, breaking hard or softly there is no noise.

Just before stopping say at 5mph ( hard or soft braking) it starts, and just before you stop it goes away.

With The wheel raised, it rotates easily so not binding, callipers are cool so not overheating. And I get good mpg.

I suspect due to a (now fixed) leaking strut, and in preperation for painting the brake callipers I have been cleaning the callipers up with fairy liquid and a powerwasher and brake cleaner, so I guess may have cleaned off any coppa slip.

Note mercedes dont advocate using any paste on these pads if my understanding is correct.

Here is the old nearly worn out pad

The bottom pin is how they were and the top pin is how they clean up with brake cleaner
Note the pads have been cleaned up a little, but I tried to lesve the coppa slip as it was.

Is there supposed to be a half circle indentation?

This part no is ending 421 06 10
Whereas , Oddly the new part no A 0044208020
Did they put in the wrong part? ( the original owner did use a scruffy garage for a few things)
Or are these old ones, not real Mb brake pads.

Any tips what might be causing break squeal most appreciated .
The pins came out easily, and the bearing surface on the caliper looked ok.

Or will it go away with a good clean up and some coppa slip on piston heads and back of pads and some pagid break gease on pins and sliding surfaces.
Oh the pads pushed back by hand so not stuck.

 

[LostKiwi]

Just dust on the pads.
A smear of copper grease on the back of the pad where the piston touches and on the sliders will stop the noise.

 

[Submariner1]

Just dust on the pads.
A smear of copper grease on the back of the pad where the piston touches and on the sliders will stop the noise.

thanks so much

 

[Submariner1]

Got caught out with no 20mm socket so had to put back the old pads. I cleaned and coppa slipped everything.
You were totally right ... silence ... definitely is GOLDEN

 

[LostKiwi]

Don't overdo the copper grease - it can contaminate braking surfaces if you aren't careful. It just needs a smear on metal to metal contact points.

 

[Submariner1]

Don't overdo the copper grease - it can contaminate braking surfaces if you aren't careful. It just needs a smear on metal to metal contact points.

Thanks I just put some ( thin smear) on:-
- the circle where the pistons left a mark.
- the pins as they go through the pad backing holes and spring clip, not near the ends of the pins that go throuh the calliper.
- all the touch points on the spring clip.
- top and bottoms of the metsl pads backing ... where they touch/slide on the caliper

I think I know what you mean. My friend had her pads changed, and she said the brakes were now crap.
It looked like an awful lot of copper slip was put on the top and bottom of the metal pad backing, ... so much that it had dripped down onto the disc and was beautifully smeared right round the disc.
In the wet ... it was as though they didnt have any bite. Personally I would prefer them squealing like mad.
Only good thing was her disc didnt go rusty over night lol!

I spent ages washing those pads in Brake Cleaner and then even meths. Yes better ..l but not good. In the end I told her to go and get a new set of pads and cleaned the calliper out and washed the disc 4 or five times... and then they were good again.
I could only imagine that grease got "injected" into the grippimg face of the pad.
Whats worse is the hotter ( and therefore generally that meant the car was going faster ) they got, the worse they were

 

[dedicatedtoMB]

Glad to hear you fixed an annoying squeak. Got me thinking. I had the same issue and was told it was rear discs worn (the air not being able to escape past the lip) I changed the discs but not the pads (they were quite new) and the squeal stopped. Ironically now starting to get a squeal from the front so will do similar. Maybe there is more than one way to skin a cat...

 

[Botus]

in this day and age wash the dust off and then stand on the brakes a few times,
getting spanners out and using copper slip is very much old school and almost always completely unnecessary

 

[dedicatedtoMB]

in this day and age wash the dust off and then stand on the brakes a few times,
getting spanners out and using copper slip is very much old school and almost always completely unnecessary

Would love to agree but sometimes the discs are too far gone and the old ways just don't work. Trust me I tried it but slamming on the breaks at 80 mph only got me an ear bending from she who must be obeyed!!!!

 

[Rappey69]

I ordered a caliper rebuild kit for my suzuki 4x4.. In it was written "do not use copper grease as it will attack the rubber seals" Now that confirmed what i had discovered..
Was going off roading for the day and a front caliper was seized.. We quickly took it off, unseized it temporarily and put some copper grease around moving parts to just get through the day.
2 weeks later when i came to rebuild the caliper the rubber boot had completely shriveled up and tore like paper !
Brake (not break???) pads more often than not come with backing shims (so the internet says) and these should never be greased as that defeats the purpose of the shims..
Using copper grease is apparently old school and no longer a good idea.
Copper grease is an anti seize and copper being a good conductor evaporates what it is suspended in when very hot, leaving the copper, but when in contact with aluminium wheels can create electrolysis , leaving a white powdery residue.
A anti corrosive jointing compound designed to inhibit electrolytic decomposition between dissimilar metals should be far more effective as that would stop metals from sticking in the first place..

 

[JohnArnoldBrown]

Just close the windows and turn the AC on.