Squealing Brakes

[32272]

Hello everyone, my 16 year old 190E has recently had a 36k type service at the same MB dealership that has looked after it for several years. Until now I have been very happy with the work done, but with a few extra repairs included, the bill this time was over £1100! Included was a front brake disc and pad change, and ever since, the brakes squeal at low speed. I've taken it back, but been fobbed of with '' they need bedding in '' After 300 miles it's still the same. On the last visit the guy drove it with the brakes and accelerator on at the same time, then told me nothing was wrong. they still squeal. I get the impression that this dealership, recently moved to brand new premises outside Bath, do not like older vehicles spoiling their view! I have not had this problem befor with a pad/disc change, is this a common problem ? Any idea's on fixing it ? Many thanks, Andy.

 

[42864]

I do not know if they were fitted to the 190 series but check for shimms at the back of the pads (between caliper piston and pad) also check that the springs around the retaining springs are properly in place. one more thing that you can try is to put a spot of brake grease (copa slip) on the back of the pads this can sometimes stop a squeal.

Dave

 

[32272]

Thanks for the info Dave, no shims are fitted and non mentioned in my Haynes manual, so I assume this is correct, all else seems OK so I'll probably change the pads again to stop this annoying fault, regards Andy.

 

[Ian Brown]

It sounds like they have not degreased the discs properly before fitting them. You should remove the pads and give the discs a good clean with brake cleaner before fitting your new pads and smear the back of the new pads with copper grease.

 

[32272]

Thanks Ian, I'll try that, Andy.

 

[DAD190E1990]

My 1990 190E has squeeled it's brakes at slow speed since it was a few years old. It was MB serviced for the first 3 years and then Indie after that. No matter whether it was genuine or replacement brakes, it's almost always done it, especially in car parks. The squeel is caused by a vibration of the pads inside the calipers and has very little or nothing to do with disc surface or what's on the disc. The pad has shoulders and they are made of metal, steel usually. The caliper is alluminium and as some may know, Steel and Ally have a very strange relationship, so even though the shoulders of the pad's backing plate may be held in with pins and clips, it still has a small amount of play in two axis and this causes the vibration and ultimately wears. The older the caliper, the more wear and possibilty of squeel. It can't cause a 'Rattle' noise because the movement or the amount of play is so small, it makes a squeeking noise and sounds like one long tone but it's not. It is a large amount of very small squeeks made by steel rattling against ally and thier frequency makes it sound like one long squeel.

I have got used to it over the years and the only real sure fire cure is brand new calipers with new pads. This is overkill really as there may be nothing wrong with the existing calipers except that the area where the pad sits has worn and allowed room for play. Another, slightly more 'Old School' method is to apply copper grease to the pad's shoulders and the back of the pad where the piston sits against it. The copper grease attracts dirt and holds it so it's good for keeping brake dust at bay but it also stops the squeel as it pads-out the gap between pad and caliper and when it rattles and tries to squeel, it is 'Damped' by the grease and therefore quiet.
I will replace my calipers soon as i'm replacing all the suspension and brakes this year but i'm expecting the brakes to squeel again within a couple of years.

Hope that helps you.

 

[32272]

Thanks DAD for the information and help, Andy.

 

[Ian Brown]

My 1990 190E has squeeled it's brakes at slow speed since it was a few years old. It was MB serviced for the first 3 years and then Indie after that. No matter whether it was genuine or replacement brakes, it's almost always done it, especially in car parks. The squeel is caused by a vibration of the pads inside the calipers and has very little or nothing to do with disc surface or what's on the disc. The pad has shoulders and they are made of metal, steel usually. The caliper is alluminium and as some may know, Steel and Ally have a very strange relationship, so even though the shoulders of the pad's backing plate may be held in with pins and clips, it still has a small amount of play in two axis and this causes the vibration and ultimately wears. The older the caliper, the more wear and possibilty of squeel. It can't cause a 'Rattle' noise because the movement or the amount of play is so small, it makes a squeeking noise and sounds like one long tone but it's not. It is a large amount of very small squeeks made by steel rattling against ally and thier frequency makes it sound like one long squeel.

I have got used to it over the years and the only real sure fire cure is brand new calipers with new pads. This is overkill really as there may be nothing wrong with the existing calipers except that the area where the pad sits has worn and allowed room for play. Another, slightly more 'Old School' method is to apply copper grease to the pad's shoulders and the back of the pad where the piston sits against it. The copper grease attracts dirt and holds it so it's good for keeping brake dust at bay but it also stops the squeel as it pads-out the gap between pad and caliper and when it rattles and tries to squeel, it is 'Damped' by the grease and therefore quiet.
I will replace my calipers soon as i'm replacing all the suspension and brakes this year but i'm expecting the brakes to squeel again within a couple of years.

Hope that helps you.

Bad news my friend The caliper is not alluminium they are cast and it is not pad vibration that causes the squeal.

 

[tom7035]

Bad news my friend The caliper is not alluminium they are cast and it is not pad vibration that causes the squeal.

Hi Ian. Only 50% correct here I'm sorry, caliper is cast, but it IS pad vibration which causes the noise. Noise IS vibration, and it is very high frequency vibration which sounds like a squeal (as DAD correctly points out), hence 'anti-squeal' paste or 'Copa-slip' or whatever on the back of the pads, or in many cases 'anti-squeal' shims.
I have in the past actually cut a hacksaw slot in pads to eliminate a piercing squeal (when I was young and broke - wouldn't do it now of course even though I'm old and still broke), as this changed the frequency wavelength hence changed the noise, sometimes even eliminating it!

 

[Ian Brown]

Softer material on the pads will reduce squealing harder material will increase squealing

 

[rallen]

Isn't aluminium too soft to withstand the pressures? All the calipers I have held were heavy as anything, looked like iron and rusting too.

Some pads come with a shim attached to the back where the piston sits, to eliminate noise? And some other pads come with a vertical split identation down the middle at the back, about 2-3mm deep.

 

[DAD190E1990]

Bad news my friend The caliper is not alluminium they are cast and it is not pad vibration that causes the squeal.

I think you will find they are cast ally, just like lots of brake calipers since the late 70's have been. Cast ally wears out too, in fact the likelyhood of any production car having 'Billet' Ally calipers is slim and so it would stand to reason that the hundreds of calipers i have overhauled in the last 20 years would be cast ally too and they, 'My Friend' were worn.

 

[Ian Brown]

My 1990 190E has squeeled it's brakes at slow speed since it was a few years old. It was MB serviced for the first 3 years and then Indie after that. No matter whether it was genuine or replacement brakes, it's almost always done it, especially in car parks. The squeel is caused by a vibration of the pads inside the calipers and has very little or nothing to do with disc surface or what's on the disc. The pad has shoulders and they are made of metal, steel usually. The caliper is alluminium and as some may know, Steel and Ally have a very strange relationship, so even though the shoulders of the pad's backing plate may be held in with pins and clips, it still has a small amount of play in two axis and this causes the vibration and ultimately wears. The older the caliper, the more wear and possibilty of squeel. It can't cause a 'Rattle' noise because the movement or the amount of play is so small, it makes a squeeking noise and sounds like one long tone but it's not. It is a large amount of very small squeeks made by steel rattling against ally and thier frequency makes it sound like one long squeel.

I have got used to it over the years and the only real sure fire cure is brand new calipers with new pads. This is overkill really as there may be nothing wrong with the existing calipers except that the area where the pad sits has worn and allowed room for play. Another, slightly more 'Old School' method is to apply copper grease to the pad's shoulders and the back of the pad where the piston sits against it. The copper grease attracts dirt and holds it so it's good for keeping brake dust at bay but it also stops the squeel as it pads-out the gap between pad and caliper and when it rattles and tries to squeel, it is 'Damped' by the grease and therefore quiet.
I will replace my calipers soon as i'm replacing all the suspension and brakes this year but i'm expecting the brakes to squeel again within a couple of years.

Hope that helps you.

I thought you said in your first post you had just inherited the car so how has your brakes been squealing for years it is definitely not worn callipers with such little mileage on it

 

[DAD190E1990]

I have just inherited the car, i was refering to it as My car because it is now my car. I also remember what has happened to it throughout it's life with it previously being my fathers car, such as it's brakes squeeling.
As for it's mileage, it is 83,000 miles and it has squeeled it's brakes from almost new. It is fair to say, which i obviously didn't mention earlier, that the caliper to pad backing clearance on a mass produced car will always vary and some calipers will squeel from new where some don't due to varying manufacturing tolerances. I didn't mention this and as Ian has so enthusiastically picked up the gap in my information, i thought i should correct my previous post.

If 20 years of experience restoring and repairing all types of vehicle meets this kind of response then i have obviously wandered into the wrong place and i apologise for having interupted. I will no longer take any part in Technical discussions or replying to any post.

 

[tom7035]

Now now, lads, can't fall out over a silly brake squeal! Far more important things to discuss and 'opine' (?) about on the forum - there's money to be saved!

 

[Ian Brown]

Now now, lads, can't fall out over a silly brake squeal! Far more important things to discuss and 'opine' (?) about on the forum - there's money to be saved!

I personally don’t think new callipers will cure the brake squeal if the pads are glazed or the pads are made of hard materials or the discs are black from deposits from the pads. The harder the pad the less brake dust but more chance of squealing, the softer the pad material the less chance of brake squeal but wheels turns black with dust. So I would rather fit OEM pads and save money compared to buying new callipers I have had a 190 now for ten years 140,000mls on it and never had a brake squeal, and if callipers do get worn mine must be worn by now surely so why no brake squeal? So this is my way of saving money, fit origional pads and not the cheap ones.

 

[rallen]

I think you will find they are cast ally, just like lots of brake calipers since the late 70's have been. Cast ally wears out too, in fact the likelyhood of any production car having 'Billet' Ally calipers is slim and so it would stand to reason that the hundreds of calipers i have overhauled in the last 20 years would be cast ally too and they, 'My Friend' were worn.

If they were alluminium then they should feel considerably light. I have taken out calipers on a Ford and two Volvos and they were very heavy, cannot believe they could be aluminium. They were also very rusty all over and had to clean the internal surfaces of all the rust for the pads to sit in properly.
I have also held similar sized alluminium alloys destined for airplanes and they are very very light, nothing like a lump of iron. The difference in weight is very noticeable.