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Old 06-03-2024, 04:24 PM   #1
tyler_win_photo
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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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Old 06-03-2024, 04:37 PM   #2
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Probably not hot enough, and not getting an even transfer layer.
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Old 06-03-2024, 04:43 PM   #3
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Originally Posted by tyler_win_photo View Post

Am I just running the rotors or pads too hot causing the vibration? I currently have no ducting.
Try getting some rotor temp paint and temp stickers for the calipers.

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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Old 06-03-2024, 06:37 PM   #4
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Try getting some rotor temp paint and temp stickers for the calipers.

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.
I moved to a BBK, DOT4 fluid and brake ducting because a loss of brakes is one of my biggest fears at the track. IMO, the two scariest things on track is a complete loss of brakes and a complete loss of traction.

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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Old 06-04-2024, 05:28 PM   #5
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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:
Originally Posted by tyler_win_photo View Post
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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Old 06-06-2024, 12:10 AM   #6
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Originally Posted by RT-BRZ View Post
I moved to a BBK, DOT4 fluid and brake ducting because a loss of brakes is one of my biggest fears at the track. IMO, the two scariest things on track is a complete loss of brakes and a complete loss of traction.

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.
Thankfully the XP12 F and XP10 R have been holding up to the track. No fade at all. When I was running XP8 F/R I would get slight fade near the end of the session.
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Old 06-06-2024, 12:18 AM   #7
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Originally Posted by 86league View Post
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.
My rotors look more like a smear of light blue than little dots as seen in your photo. Do you run with ABS or TC on? Possibly ABS is causing those uniform hot spots.

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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Old 06-06-2024, 11:30 AM   #8
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Originally Posted by tyler_win_photo View Post
My rotors look more like a smear of light blue than little dots as seen in your photo. Do you run with ABS or TC on? Possibly ABS is causing those uniform hot spots.
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!
I do run ABS, but no TC (pedal dance). ABS was my first thought too - although the dots are not exactly what I'd seen from ABS in the past. But -- I had several sets of rotors where I was REALLY careful to not trigger ABS and still had that issue, progressively worse as I put heat into the system (now assuming the hub).


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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Old 06-10-2024, 02:59 PM   #9
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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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Old 06-11-2024, 12:52 AM   #10
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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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Old 06-14-2024, 02:20 PM   #11
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The dots on the rotor color align with the rotor vanes, not likely ABS related.
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Old 06-18-2024, 10:57 AM   #12
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The dots on the rotor color align with the rotor vanes, not likely ABS related.
They don't actually align with the pillars. That was one of my thoughts as well but it didn't pan out.
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