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Posted: 5/12/2024 12:25:52 PM EDT
[Last Edit: aa777888-2]
Replaced the brake pads and rotors on a 2014 Porsche Cayman (981). Used OEM parts and a proper torque wrench. Made everything super clean before reassembly.
Went out to bed in the brakes and experienced a turbine-like whine on braking. This continued throughout the bedding process. Came back home and this is what I see. Not good!  Attached File |
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Posted: 5/12/2024 12:45:19 PM EDT
[Last Edit: BobbyHill]
[#1]
That looks like a manufacturing finishing defect but me just machinist.
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AZ, USA
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Posted: 5/12/2024 1:01:23 PM EDT
[#2]
I'm with him ^ though I'm not sure it's a defect, that pattern looks like it's coming from the
rotor finish possibly having a ramp across the machining path rather than being level, probably a worn cutter. I'd think Ze German QC guy would reject it if it was that out of spec though. Replace rotor, rotor refinish or just let it wear in. Kind of funky that the wear points are also spread regularly from hub to edge, probably more machining issues. I can't think of a mechanism with a pad failure that would do that so regularly. I could see it vibrate but not so consistently as to keep hitting the same wear points. |
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MO, USA
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Posted: 5/12/2024 1:25:18 PM EDT
[#3]
I'd contact Porsche or the mfg of the rotors to see what they say.
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Posted: 5/12/2024 1:26:46 PM EDT
[#4]
Quote HistoryOriginally Posted By nophun: I'd contact Porsche or the mfg of the rotors to see what they say. This strange pattern. |
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TX, USA
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Posted: 5/12/2024 2:48:33 PM EDT
[#5]
Need pics of the rotor on opposite side.
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Posted: 5/12/2024 5:02:57 PM EDT
[Last Edit: aa777888-2]
[#6]
I took a more careful look. The problem is only on the left rotor. In fact, it's only on the outside of the left rotor. Perhaps it is something wrong with that one pad? I'll take it apart again and look at it more carefully to try to find more clues. |
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Posted: 5/12/2024 11:38:23 PM EDT
[#7]
I disassembled the caliper in question. Damn if I can find anything wrong with it
 
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USA
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Posted: 5/13/2024 7:29:14 AM EDT
[#8]
Quote HistoryOriginally Posted By aa777888-2: I disassembled the caliper in question. Damn if I can find anything wrong with it Wonder if the caliper is holding it properly |
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Posted: 5/13/2024 7:34:15 AM EDT
[#9]
It looks exactly to me like when you try to lap or stone a piece of metal that isn't flat. Which is exactly what's happening when you apply your brakes. It's probably less than .002" of problem but it's not right.
You can take it and have it turned if you really don't want to exchange it for whatever reason. But a photo should get you a replacement sent. |
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Posted: 5/13/2024 9:18:02 AM EDT
[#10]
Looks like weird machining
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Posted: 5/13/2024 9:39:21 AM EDT
[#11]
Currently working on a replacement. Sent photos, they did not immediately dismiss the issue. It's a huge PITA because if the RMA is approved I have to ship it back (on their nickel) first before they'll send me another. I.e. the car is immobilized until I can get another rotor. I tried asking if I can pay for another and then they can credit me when they get the old one back but they apparently don't have a process for that
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WA, USA
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Posted: 5/13/2024 10:06:14 AM EDT
[#12]
First post! Helical machine marks are not normal.
The most practical solution would be to have a good local shop turn that rotor, and put it back together. About twenty bucks, and fixed same day. |
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Posted: 5/13/2024 10:15:16 AM EDT
[#13]
Quote HistoryOriginally Posted By whiskerz: Looks like weird machining Yep. OP bought a rough unfinished rotor, and the pads are only touching the high spots. If he can feel/hear it, it's probably not a consistent thickness either. I guess it's time to put the old rotor and pads back on while awaiting the RMA process. |
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Posted: 5/13/2024 12:26:34 PM EDT
[Last Edit: JackRebney]
[#14]
Odd. Kinda looks like it was blanchard ground.
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Posted: 5/13/2024 8:31:17 PM EDT
[#15]
They approved the RMA.
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Posted: 5/13/2024 9:03:18 PM EDT
[#16]
ost.
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CO, USA
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Posted: 5/14/2024 12:11:41 AM EDT
[#17]
Can you grab any of the groves with your finger nail?
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Posted: 5/14/2024 10:20:58 AM EDT
[#18]
The helical marks I can't feel. The "dashed circles" you can feel with a fingertip.
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