Melted Wheel Center Caps

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blueline
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Just an FYI that Apex center caps can melt on track days, so my Carpokes PSA (from recent personal experience) is to remove them before getting on track. :mrgreen:

I didn't have center caps on any of the CCW wheels for the Corvette track car, so it was never anything I thought about back then. Anyway, I forgot to take them out of the new Apex wheels that I got for the GT4. (Besides, the caps looked good!) Best reserve the caps for off-track excursions. Lol.

Apex melted ctr cap Oct 2023.jpg
Apex melted ctr cap Oct 2023.jpg (2.34 MiB) Viewed 1681 times



They are out now...

Apex sans center cap Oct 2023.jpg
Apex sans center cap Oct 2023.jpg (2.63 MiB) Viewed 1681 times
Tim
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Tom
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Wow, that's crazy. ABS melts at 212F, and I'm guessing those caps are made of an even more heat resistant plastic. You'd think Apex would have anticipated track-braking heat...?

Excuse my track naivete, but what are the sharpie marks on the rotor? Checking for wear patterns? And is it just the picture, or are those rotors pretty grooved up?

I have to say, I kind of like the no-cap look on that wheel. :)

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blueline
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In all fairness, the center caps are not designed to withstand the intense heat generated by serious on-track driving. Apex recommends removing the center caps for track use (something I overlooked!), so that's really on me.

The rotors are AP Racing's Competition J-Hook rotors and they are excellent track-oriented rotors. The "sharpie" marks are actually the J-hook shape of the heat dissipating slots on the rotors. Not drilled either - I don't like drilled rotors - they reduce strength, induce long cracks and don't add anything to the performance or heat dissipation of the rotor. It's more of a marketing angle - "Cross-drilled and slotted" sounds good.

Yes, some smooth grooves but also some of what you're seeing is the burnishing from the well-matched Ferodo DS3.12 race pads. These rotors have close to 2,000 hard track miles on them so, while they are still performing magnificently, they are showing their age. (Kind of like me ... :lol: ). However, still plenty of material and thickness and only tiny, short crazing. (New the thicknesses of the rotors are 34mm ft and 30mm rear.) It's an awesome brake setup for track.

https://www.essexparts.com/essex-design ... tiron-rear

https://www.essexparts.com/essex-design ... 991t-997ts
Tim
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Tom
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blueline wrote: Thu Oct 19, 2023 7:23 pm The "sharpie" marks are actually the J-hook shape of the heat dissipating slots on the rotors.
Interesting! I learn something new every day! Never saw that before, and even after hearing what they are, they still look drawn on to me. :lol:

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blueline
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Tom wrote: Thu Oct 19, 2023 7:30 pm
blueline wrote: Thu Oct 19, 2023 7:23 pm The "sharpie" marks are actually the J-hook shape of the heat dissipating slots on the rotors.
Interesting! I learn something new every day! Never saw that before, and even after hearing what they are, they still look drawn on to me. :lol:
Well, they are full of brake dust that's "sharpie" black! Lol.

As a comparison, Brembo rotors have similar slots that, depending on how photographed, could look drawn on!

brembo-2-piece-disc-380x34mm-slotted-type-3-med.jpg
brembo-2-piece-disc-380x34mm-slotted-type-3-med.jpg (29.85 KiB) Viewed 1661 times

By the way, the links for the AP Racing rotors contain a good amount of info, data, and diagrammed pics.
Tim
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How funny, I have seen brakes like that. I guess the black made me think they were a whole different thing. :)

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blueline
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Tom wrote: Thu Oct 19, 2023 7:58 pm How funny, I have seen brakes like that. I guess the black made me think they were a whole different thing. :)
Speaking of temps, rotors on track typically run in the 400° to 650° range, constantly going up and down from turns to straights to turns. As I understand it, they can reach into the 800's in extreme circumstances (real racing), so even though center caps and wheels are somewhat removed from the rotors, they will still easily exceed the ABS 212° threshold.
Tim
Current:
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'24 Cayenne S - Algarve Blue Metallic
'21 718 Cayman GTS - Black
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I had a similar but not that serious experience two weekends back Tim. I was running my OZ Ultraleggras with the standard OZ caps. I had removed the OZ center decals and added some Porsche crest logos that I had made from a vendor on etsy. The etsy vendor sold them as center caps for wheels, with the heat the sticker started to come up. Next outing I will remove the center caps as well. :thumbup:
Last edited by J-Dub on Fri Oct 20, 2023 9:09 am, edited 1 time in total.
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Tom wrote: Thu Oct 19, 2023 7:58 pm How funny, I have seen brakes like that. I guess the black made me think they were a whole different thing. :)
Photo of one of my AP Racing J-Hook 2-piece rotors when new before installation. The other pic is the new AP Racing rotor next to the GT4 Porsche OEM rotor. Huge difference in cooling fins (number and design), weight, rotor material, etc. The front OEM rotors were already shot at only about 1,000 track miles. They were below minimum thickness, were grooved, had unsafe cracks (long ones emanating from the drilled holes), etc.

OEM to AP Racing is night and day.

AP Racing rotor new May 2022.jpg
AP Racing rotor new May 2022.jpg (2.99 MiB) Viewed 1639 times
AP rotor vs GT4 OEM May 2022 #1.jpg
AP rotor vs GT4 OEM May 2022 #1.jpg (2.44 MiB) Viewed 1639 times
Tim
Current:
'26 911 Carrera S - PTS Verde British Racing Green
'24 Cayenne S - Algarve Blue Metallic
'21 718 Cayman GTS - Black
'22 911 Turbo S - Carmine Red
'21 718 Cayman GT4 - White
'11 GMC 1500 Quad Cab 4x4 - Black

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Yep, take them out. It's funny I used to do HPDE in a S550 Mustang, I had 18" Apex wheels on that as well. No heat issues. With the Cayman I had the caps melt , and cannot keep the wheel weights on with the heat.
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