Squeaky Brakes after application.

[Sleek Lemur]

Hi everyone, I'm still struggling with my brakes !

1970 auto.

We had always suffered from a little bit of brake squeak at the front and this seemed to get worse. It occurred after braking, gradually reducing and returning after brake application. Sounds like the brakes aren't releasing fully, but the car rolls fine. Linkage all looks fine. Booster hasn't been touched in my 11 years of ownership. Local Merc specialist cleaned up the discs and replaced front hoses and the problem went away... but then after a 2,500 mile trip to Italy, a week after returning all brakes locked solid. Four red hot wheels and overheating. I bought a new master cylinder, but when I went to fit it the problem had disappeared! I replaced it anyway and all "kind of" ok since then. Front Brakes still squeal as before though and the noise is making it embarrassing to drive!

Really appreciate any wisdom here.

[WRe]

Hi,
did you check the right position of the brake pistons? They have to be in the right position to reduce sqeaking (see att. doc; sorry in German), to be controlled with this special former tool/molding plate (no. 19 in the doc or pic). The piston position should be 20 degrees against  the guidance face of the calliper. The tool can be selfmade of cardboard.
Did you grease the back of the brake pads with some copper or ceramic paste?
...WRe

[mrfatboy]

I would like to know more about this also.  I'm currently in the middle of doing a complete brake job. Replacing fluid,  pads,  and rotors. 

A couple of weeks ago I just replaced the front pads and that's when my squeaking started.

[WRe]

Hi,
the brake piston must be inserted in such a way that the ridge on the piston is pointing down with built-in brake caliper. The ridge causes
a slight one-sided application of the brake pads when braking. This will reduce the tendency of squeaking.
For easy piston correction you need a special piston spin gripper.
...WRe

[Sleek Lemur]

Guys, thank you !

I will have a look.

[Benz Dr.]

Check the free play on the push pin going into your brake booster. Normally, you can set the eccentric to point towards the firewall but sometimes that's too much. If you notice the brakes locking up again check to see if it's slightly loose. If not, you can turn the eccentric a bit which should make your brakes release.

[Sleek Lemur]

Thanks, WRe. Two obvious questions. Where can I get a piston gripper and 2, any hints on an alternative ?

[Sleek Lemur]

Many thanks, Dr Benz. This item is found in in the footwell under the dash ?

[Mike K]

I had similar issues and redid my brakes, completely, it's something I wasn't prepared to take a chance with.
Installed new booster, new master cylinder, new callipers x4, and stainless steel braided brake hoses, new rotors, and new brake shoes at rear -all issues solved!

Best,
Mike

[Mike K]

I would like to know more about this also.  I'm currently in the middle of doing a complete brake job. Replacing fluid,  pads,  and rotors. 

A couple of weeks ago I just replaced the front pads and that's when my squeaking started.

To resolve squeaking when replacing brake pads, I use anti squeal paste on the back of the pads, works really well-
https://www.amazon.co.uk/Liqui-Moly-Brake-Anti-Squeal-Paste/dp/B00295D9VQ

Best
Mike

[Mike K]

Many thanks, Dr Benz. This item is found in in the footwell under the dash ?

Here's a picture of the engine bay at the brake booster, which explains what Dr Benz is talking about. I put this together for a friend who was experiencing similar issues. The pic is of my LHD 280SL, if yours is a RHD, the booster will obviously be on the opposite side.

Best,
Mike

[WRe]

Hi,
a piston turning tool (http://www.ate-info.de/en/details/produkte/kolbendrehzange) is expensive and you need it only once in your life. Maybe you can borrow it from somebody. Alternatives are quite difficult and depend on smooth-running pistons. Sorry I have no idea at the moment.
...WRe

[Sleek Lemur]

Mike, Thank you for your messages. Really appreciate the help. Am guessing I need to increase pedal height, yes ?

I have considered getting a new booster and also sending the calipers off for a refurb. I think I'll do that when the weather gets worse, which in England could be anytime !

[Sleek Lemur]

Hi,
a piston turning tool (http://www.ate-info.de/en/details/produkte/kolbendrehzange) is expensive and you need it only once in your life. Maybe you can borrow it from somebody. Alternatives are quite difficult and depend on smooth-running pistons. Sorry I have no idea at the moment.
...WRe

Thank again, WRe and please don't apologise, everyone has been v helpful. Am getting back into home mechanics after a 20 year break and my tiny brain is having trouble !

[Mike K]

Mike, Thank you for your messages. Really appreciate the help. Am guessing I need to increase pedal height, yes ?

I have considered getting a new booster and also sending the calipers off for a refurb. I think I'll do that when the weather gets worse, which in England could be anytime !

Yes I would think that you need to increase brake pedal height.
Turning the bolt so that the notch on the bolt head moves towards the firewall will increase the brake pedal height.
You can play around with this, (it's not a difficult adjustment to make), as you need to ensure that there's not too much brake pedal travel before the brakes engage.

I would also recommend that you either service or replace or the callipers. I initially bought calliper repair kits and pistons:
https://www.mbclassics.de/ATE-repkit-rear-caliper-42mm
https://www.mbclassics.de/repkit-brake-caliper-front-57mm
https://www.mbclassics.de/piston-for-rear-brake-caliper-42mm-108-109-111-113
https://www.mbclassics.de/piston-front-brake-caliper-57mm-108-109-111-113-114-115

However when I removed the callipers I could see that they hadn't been serviced for the life of the car, 47 years. I decided to rather replace all 4 callipers with new, for peace of mind. This is something you really don't want to take chances with.

Let us know how you get on.

Best,
Mike

[Sleek Lemur]

Well, I needed to grease the suspension, so I took the brake pads out to check the alignment. Drove the car and somehow the pedal has a lot more "give" in it. Perfectly efficient, don't need to pump the pedal, just different than previously. But....not a sign of the squeaking ! I'm going to get a rep as a time waster!

Mike, there's a company in UK that completely refurbs calipers and I will send mine off in the autumn.

Let's see if the problem returns.....