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Tracking / Autocross / HPDE / Drifting What these cars were built for! |
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#1 |
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Rotor Warping/Deposit on Track
I have been experiencing a warped/pad deposit feeling on track leading me to change rotors almost every track day. The feeling is more notable when light/trail braking at high speeds. When I am on the brake 100% the issue is almost non-existent. The vibration becomes apparent from the second hot lap onwards. Pads have been bedded in and are warmed up before full brake application. A full 2 mile cool down lap after every session as well.
I run Carbotech XP12 in the front and XP10 in the rear on an OEM non-PP brake and rotor setup. The car has FI making about 270whp. Am I just running the rotors or pads too hot causing the vibration? I currently have no ducting.
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#2 |
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Probably not hot enough, and not getting an even transfer layer.
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Not 100% sure how much extra power the stock brakes can handle. I see some track owners swap them for BBK even with stock power but most people seem to think that is overkill.
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The whole point of this stuff is enjoyment for me and the idea of cutting corners on brakes just doesn't compute. If I'm willing to do that then I guess a helmet is optional too. ![]() |
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Your situation sounds exactly like mine - hard braking eliminated the shudder, but lighter braking once the brakes were warm shuddered.
Do you have pics of the rotor - are there a bunch of little dots around it? I was desperate and just replaced the front hub on the one that had the worst "spots" on the rotors. Problem solved. There was no play in the hub when "cool" after a session that I could feel, but there apparently was enough play in the hub bearings once warm to cause the wobble. Clamping the rotor hard with the brakes gave it enough support to not wobble. If that's not it : lots of reports of issues with uneven transfer layers with carbotech pads resulting in brake shudder. I moved away from them while trying to fix my "brake" problems just to eliminate that as a variable. This was 2 driver front rotors from the same weekend. Changed after the first day, then after the 2nd day. Passenger front had a tiny hint of the same issue - but really hard to see. I ended up swapping that hub as well to completely fix any hint of shudder on braking. Quote:
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#6 | |
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Now that you mention it, it could by the hubs. My car has about 75k miles. There is no play when cold, but it might have play when it's warm. Thanks for the insight!
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I did not log data to verify hub tone ring wasn't sending bad wheel speed data causing ABS activation - so I can't rule it out. In the end the new hubs (which include the wheel speed sensor tone ring) 1000% solved the issue though, so even if it was ABS the cure was the same - new hub. After replacing it was night and day better, dead smooth for all 4 sessions. I really didn't think replacing a hub would fix the issue. I did it out of desperation as I had tried most everything else short of buying the AP Sprint BBK. The hub was avail at a local Autozone, was a lot cheaper, and I could just swap it out that Sat night in an attempt to salvage Sunday. |
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With zero data or video, I'd be willing to bet you're getting your pads pretty hot, and then parking with insufficient cooldown, resulting in deposits.
The deposits are the vibrations. Step up to a better pad AND do way more cooldown. |
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Ducting may help but I think with stock brakes you are over the limit of the amount of heat you can dissipate to keep those pads in their happy place.
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#11 |
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The dots on the rotor color align with the rotor vanes, not likely ABS related.
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