986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post

bwdz · 09-22-2017, 02:10 AM

Sounds like you are very mechanically inclined as you have changed the brakes twice and tried all the old mechanic remedies to fix the squeal but let's just go back and look at what causes brake squeal and see if we can find anything else.
Brake squeal is caused by vibration. The vibration plays out just like an on LP record player and can change the pitch depending on what is causing it and how it is being transferred. All brake squeal reducing/eliminating products that you have tried basically try to dampen the pad (in my record player analogy it would be like putting an isolator on the needle so it no longer feels the bumps on the record and produces no more sound) What this brings me back to is that you still have a vibration. The vibration is the rotor surface being uneven, glazed, warped or otherwise affected. You must find the source of the rotor problem. Dial indicators are dirt cheap on ebay. You need to do a serious rotor runout test and see what is actually going on. I am making these assumptions based on the number of pads you have tried so I am eliminating that the pad material is causing this problem. You may have some buildup on your hubs where the rotor sits that you have not cleaned properly and the rotor may be moving out of round just so slightly because it is not sitting on the hub perfectly even or there is some damage to the hub itself. A dial indicator with a magnetic or clip on arm will allow you to test the hub and the rotor (of course index the rotor and hub and tighten it to the hub before you do the rotor runout).
I am suggesting this because you have already replaced everything twice or more. There are not many more things to check. It is unlikely that you got 2 sets of warped rotors so the only things besides runout on the hub that could be causing this would be things like overtightening your wheels (which will cause slight rotor warpage at times) improper bedding in of the pads etc... I say check the runout on the hubs and then check the runout on the rotors while installed on the hub and go from there.

09-22-2017, 02:10 AM	#20
bwdz Registered User Join Date: May 2016 Location: Northville, MI Posts: 249	Sounds like you are very mechanically inclined as you have changed the brakes twice and tried all the old mechanic remedies to fix the squeal but let's just go back and look at what causes brake squeal and see if we can find anything else. Brake squeal is caused by vibration. The vibration plays out just like an on LP record player and can change the pitch depending on what is causing it and how it is being transferred. All brake squeal reducing/eliminating products that you have tried basically try to dampen the pad (in my record player analogy it would be like putting an isolator on the needle so it no longer feels the bumps on the record and produces no more sound) What this brings me back to is that you still have a vibration. The vibration is the rotor surface being uneven, glazed, warped or otherwise affected. You must find the source of the rotor problem. Dial indicators are dirt cheap on ebay. You need to do a serious rotor runout test and see what is actually going on. I am making these assumptions based on the number of pads you have tried so I am eliminating that the pad material is causing this problem. You may have some buildup on your hubs where the rotor sits that you have not cleaned properly and the rotor may be moving out of round just so slightly because it is not sitting on the hub perfectly even or there is some damage to the hub itself. A dial indicator with a magnetic or clip on arm will allow you to test the hub and the rotor (of course index the rotor and hub and tighten it to the hub before you do the rotor runout). I am suggesting this because you have already replaced everything twice or more. There are not many more things to check. It is unlikely that you got 2 sets of warped rotors so the only things besides runout on the hub that could be causing this would be things like overtightening your wheels (which will cause slight rotor warpage at times) improper bedding in of the pads etc... I say check the runout on the hubs and then check the runout on the rotors while installed on the hub and go from there.