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08-27-2014, 12:56 PM | #23 |
Midlife Crises Racing Silent but Deadly Class
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Inspect the rotor surface for tell-tale signs of an outline for a pad. If there is one, that's your culprit right there.
The parking brake shoes are so close to the center of the rotation that some rust deposit does not and should not cause brake shudder. They are not your concern, although that would likely be the culprit of the sound you hear when the calipers are off the rotors. Take a sprayer (Windex bottle or something) and spray some water on the brake rotors. Let sit over night and let a light layer of rust develop. Then take the car out and do a couple of really hard braking, like from 60mph to 5mph without triggering ABS. If the brake shudder remains, you may have to turn the rotor, although the rotors on our cars have such small tolerances from new (it's like 1.2mm or something crazy like that from new to min thickness) that turning them would be a waste of money. The new rust layer and the immediate bedding after should result in the old high-spots being eliminated along with the new rust. I would suspect a worn bushing, like the front lower control arm bushing, if the brake shudder remains after a new layer of rust has developed and removed.
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08-27-2014, 01:16 PM | #24 |
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^I haven't heard that one before; great idea.
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08-27-2014, 02:56 PM | #25 |
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Update:
I put the wheels back on and tried pushing/pulling at 3/9 and 6/12. No play. I took the rotors off, there was some light rust trapped in with the parking brake. Spun the hubs, no more grinding. So, probably not wheel bearings. I also took the rotors over to a local shop to get turned. I know, people think thats a waste of money. But, I can pay them $40 to turn both rotors, including the parking brake surfaces, and be 100% certain any deposit is gone. Or, I can spend an hour or two screwing around with the new surface rust, rebedding, etc., etc., be about 90% confident the deposit is gone. The time savings is worth $40 to me, and the extra confidence is a nice bonus. Also, they had no problem that they were drilled. Will update everyone once I get them back. Very much appreciating everyone's help with the diagnosis, such a great community we have here. |
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08-27-2014, 02:57 PM | #26 |
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By the way, Hack that is a clever idea. If I didn't have such a checkered history of extremely strange brake problems I would be more inclined to try it.
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08-31-2014, 12:30 AM | #27 |
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Pad deposit it was!
I got my turned rotors back, and was extremely pleased with them. Cost me all of $38, and they were so smooth you would almost think they were ground. No cutting lines visible. Swapped in the new fronts, the turned rotors, with all the usual wire brushing/cleaning of mating surfaces, and went out to bed them in. Totally smooth braking. In the last year of endless dicking around with my brakes, I had forgotten just how smooth the braking could be, and how good the stopping power was. I really appreciate everyone's help with this. Its extremely satisfying to find an issue, work through the diagnosis with with the community support, and fix the problem, while doing all the labor myself and avoiding a trip to the mechanic. I love my indy shop, but I love not having to pay someone else to do work even more. |
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08-31-2014, 08:56 AM | #28 |
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Glad to hear it is resolved
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