FYI Front brakes squealing - fixed

[124500E]

Hey guys,

I got a interesting one for you. I‘m working at Mercedes and we had a car from a customer in the shop and he had a loud squeak at the front brakes. Following parts (by my colleagues) came in:
-Front disks
-Front Pads (ATE and OE)
-New brembo calipers
-new hubs
-new „querlenker“


I tried following steps to get the car quiet.
-file down the edges of the pads
-use different types of oe brake paste
-use Jurid and ATE pads
-sticking the pads with double sided tape to the pistons
-using wheel balancing weights for getting the oscillation to another frequency

Nothing helped. So I Continued to stick weights at the suspension and steering parts. The noise disappeared as I put a weight on the steering stop bolts at the steering knuckle. They were both completely okay. I tried new ones with the same result. So I get to the lathe and made slightly heavier ones. Squeak is completely gone.



View attachment IMG_2423.MOV

Greetings Jan

 

[Kyiv]

So what exactly does this imply? Dave, could you help extracting a conclusion?

 

[Jlaa]

Impressive determination to solve a squealing issue!!! Did the customer really pay for every single hour spent in chasing down this issue? WOW.

 

[Kyiv]

Impressive determination to solve a squealing issue!!! Did the customer really pay for every single hour spent in chasing down this issue? WOW.

Mate, do you understand what the issue was and what caused it?

 

[Jlaa]

Mate, do you understand what the issue was and what caused it?

Somehow the acoustic resonance stopped when circular weights were applied to the part circled in red in the photos. I think?

 

[Kyiv]

Hmmm... Not convincing... But what do I know.

@gsxr, be our Alan Turing. What do weights on suspension parts can do to severe brake squealing?

 

[gsxr]

Wild guessing... there is something else going on, and weighting the steering stop happened to cure it.

Later Mercedes calipers use weights on the ears of brake pads (i.e., W211 AMG pads) and even the late R129 Silver Arrow calipers used weights inside the pistons as vibration dampers. So there's a factory precedent set for using weights to modulate resonance.

I'm at a loss to explain this particular scenario though!

 

[124500E]

If you are breaking the rubbing between the disc and the pads are always generating vibrations. Sometimes an other part, 99% the caliper itself, catch those vibratons and get in resonance with his own vibration --> squeking.

If you are interested in physics and resonance:

BRÜCKEN - Architektur, Technik, Geschichte

Alles über die interessantesten Brücken der Welt. Rekorde, Brückenbaupioniere, die bekanntesten und schönsten Brücken der Welt. Die längsten Brücken und die größten Katastrophen in der Geschichte des Brückenbaus

www.bernd-nebel.de

 

[sheward]

I have a set of those late SA caliper piston weights.

drew

 

[Kyiv]

If you are breaking the rubbing between the disc and the pads are always generating vibrations. Sometimes an other part, 99% the caliper itself, catch those vibratons and get in resonance with his own vibration --> squeking.

If you are interested in physics and resonance:

BRÜCKEN - Architektur, Technik, Geschichte

Alles über die interessantesten Brücken der Welt. Rekorde, Brückenbaupioniere, die bekanntesten und schönsten Brücken der Welt. Die längsten Brücken und die größten Katastrophen in der Geschichte des Brückenbaus

www.bernd-nebel.de

Could you please make an educated guess as to how this problem developed? Initially the car did not have it, and then it does. What caused it to emerge?