Squeaky Brakes
Discussion
I had some one piece discs machined down from a later model SLK, which have 345mm discs to 340mm to fit to an earlier SLK to void the cost of paying silly amounts of money for 2 piece discs originally fitted to the car. There dimension's are now the same and they're bolted onto the car with no issues.
I purchased some Pagid pads originally, fitted to go with the new modified Delphi discs. Once fitted, an unbearable screech when using the brakes. Only really disappearing when they were red hot, but there pretty much all the time and piercingly loud. Purchased some noise reduction shims, fitted to the back of the pad, no difference. Sent the pads back. Purchased some Brembo pads, fitted - exactly the same. High pitch wailing before I've even managed to reverse out the garage.
Never come across anything like this before in 15+ years in the trade. Cleaned up the old AET pads, which in fairness weren't that badly worn, just slightly mis-shapen by corrosion on the previous disc. They don't screech at all.... until they're warm (so say after half hour of stop/start normal driving).
I'm just ordering some new AET pads now, as the one thing I've noticed when swapping the pads over is the old AET pads are 3-4mm wider than the replacement Pagid & Brembo pads? I think this 3-4mm less coverage across the disc face is causing the disc to resonate?
Failing the above, I'm at my wits end and will probably just buy some original discs. I would however like to try get this working, considering it's something as simple as brakes!
Any Ideas as to why this is happening?
I purchased some Pagid pads originally, fitted to go with the new modified Delphi discs. Once fitted, an unbearable screech when using the brakes. Only really disappearing when they were red hot, but there pretty much all the time and piercingly loud. Purchased some noise reduction shims, fitted to the back of the pad, no difference. Sent the pads back. Purchased some Brembo pads, fitted - exactly the same. High pitch wailing before I've even managed to reverse out the garage.
Never come across anything like this before in 15+ years in the trade. Cleaned up the old AET pads, which in fairness weren't that badly worn, just slightly mis-shapen by corrosion on the previous disc. They don't screech at all.... until they're warm (so say after half hour of stop/start normal driving).
I'm just ordering some new AET pads now, as the one thing I've noticed when swapping the pads over is the old AET pads are 3-4mm wider than the replacement Pagid & Brembo pads? I think this 3-4mm less coverage across the disc face is causing the disc to resonate?
Failing the above, I'm at my wits end and will probably just buy some original discs. I would however like to try get this working, considering it's something as simple as brakes!
Any Ideas as to why this is happening?
It could be a hundred factors combining to make the pads resonate at an audible frequency. Sometimes adding a layer of anti-squeal paste helps - sometimes removing it helps. Same with shims. If it's a floating caliper, regreasing the sliders might help. Dirt between the caliper and pads can make a difference. The fact the disc is bolted together instead of a single cast unit will make a difference. The physical weight and stiffness of the pads will make a difference. One of the pads you show has a groove through the lining. I believe it's there to prevent cracking and nothing to do with squeal, but it will affect how the pad resonates and might be related to the problem. If the pad with this groove is the quiet one, you could try cutting something similar into the new one and see if that helps.
GreenV8S said:
It could be a hundred factors combining to make the pads resonate at an audible frequency. Sometimes adding a layer of anti-squeal paste helps - sometimes removing it helps. Same with shims. If it's a floating caliper, regreasing the sliders might help. Dirt between the caliper and pads can make a difference. The fact the disc is bolted together instead of a single cast unit will make a difference. The physical weight and stiffness of the pads will make a difference. One of the pads you show has a groove through the lining. I believe it's there to prevent cracking and nothing to do with squeal, but it will affect how the pad resonates and might be related to the problem. If the pad with this groove is the quiet one, you could try cutting something similar into the new one and see if that helps.
It's a 6 piston caliper, caliper and carrier are all in one so no moving parts other than pistons. Calipers been cleaned up where the pad tracks and pads move nice and freely. The new pad (with the groove in the middle) are the noisy ones, the old pads (no groove) are quiet when cold, noisy when warm.
I must add, this isn't a normal brake squeal - it is LOUD. Like a stone between the disc/back plate sort of loud.
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