AP J hook life

3209X · 06-13-2023, 08:20 AM

Hi everyone. I have a AP Racing kit and this is what my AP rotors look like. I know they beginning to be near the end of their life. My question is if I can still run them on the track for another weekend? There are no cracks on the rings at either the inner edge or outer edge. I removed the rotors to inspect. The brakes still feel really amazing. Its the j hooks that are starting to wear off but they arent completely flat or worn off. The track I am going to is not heavy on brakes.

yahh · 06-13-2023, 09:13 AM

There should be a minimum thickness measurement on the outer ring of the rotor or contact AP and ask them what the spec is. Measure it and you will have your answer. Realistically, if you don't have any cracks touching the edges they are probably fine especially if it's not a high-speed track.

tdott · 06-13-2023, 09:15 AM

Is there a minimum thickness stamped on the rotors? If everything else looks good and you aren't below the min thickness, then send it.

Ximian · 06-13-2023, 12:16 PM

You're unlikely to find the minimum thickness information for AP rotors. The J hooks can also function as wear indicators as once they're gone, that rotor is completely done.

When inspecting the rotor, it's best to remove it so you can check both sides. Any crack going to an edge and especially around an edge means the rotor should be replaced. Cracks where your fingernail will catch on it is also risky for a track day.

Cracks going to edges but not around should still be drive-able if you need to get home in an emergency, but I wouldn't risk it for a track day.

3209X · 06-13-2023, 03:56 PM

Quote:

Originally Posted by Ximian

You're unlikely to find the minimum thickness information for AP rotors. The J hooks can also function as wear indicators as once they're gone, that rotor is completely done.

When inspecting the rotor, it's best to remove it so you can check both sides. Any crack going to an edge and especially around an edge means the rotor should be replaced. Cracks where your fingernail will catch on it is also risky for a track day.

Cracks going to edges but not around should still be drive-able if you need to get home in an emergency, but I wouldn't risk it for a track day.

Thanks for the perspective. The min thickness is 34mm and it is above that but I do recognize the j hooks are starting to go.

Redd · 06-13-2023, 07:10 PM

They're fine to use until the slots are nearly gone.

sc_tr0jan_m3 · 06-14-2023, 04:00 PM

No cracks don’t look back!

06-13-2023, 08:20 AM	#1
3209X Registered 0 Rep 4 Posts Drives: m3 Join Date: Feb 2014 Location: canada iTrader: (0)	AP J hook life Hi everyone. I have a AP Racing kit and this is what my AP rotors look like. I know they beginning to be near the end of their life. My question is if I can still run them on the track for another weekend? There are no cracks on the rings at either the inner edge or outer edge. I removed the rotors to inspect. The brakes still feel really amazing. Its the j hooks that are starting to wear off but they arent completely flat or worn off. The track I am going to is not heavy on brakes. Last edited by 3209X; 06-13-2023 at 08:26 AM..
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06-13-2023, 09:13 AM	#2
yahh Private First Class 101 Rep 140 Posts Drives: G80 M3 / V10 R8 / Lotus Elise Join Date: Aug 2014 Location: Richmond, VA iTrader: (0)	There should be a minimum thickness measurement on the outer ring of the rotor or contact AP and ask them what the spec is. Measure it and you will have your answer. Realistically, if you don't have any cracks touching the edges they are probably fine especially if it's not a high-speed track.
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06-13-2023, 09:15 AM	#3
tdott Brigadier General 3943 Rep 3,988 Posts Drives: M3 Join Date: Nov 2010 Location: South FL / 6ix iTrader: (4)	Is there a minimum thickness stamped on the rotors? If everything else looks good and you aren't below the min thickness, then send it. __________________ N/A S65 Headers Before/After Dyno Results
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06-13-2023, 12:16 PM	#4
Ximian . 1919 Rep 1,888 Posts Drives: E92 M3 Join Date: Oct 2016 Location: MN iTrader: (1) Garage List 2011 BMW M3 [0.00] 2021 BMW M3 [0.00]	You're unlikely to find the minimum thickness information for AP rotors. The J hooks can also function as wear indicators as once they're gone, that rotor is completely done. When inspecting the rotor, it's best to remove it so you can check both sides. Any crack going to an edge and especially around an edge means the rotor should be replaced. Cracks where your fingernail will catch on it is also risky for a track day. Cracks going to edges but not around should still be drive-able if you need to get home in an emergency, but I wouldn't risk it for a track day. __________________
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06-13-2023, 07:10 PM	#6
Redd Brigadier General 3900 Rep 4,165 Posts Drives: 2010 BMW E92 M3 Dakar Edition Join Date: Jul 2015 Location: Malaysia iTrader: (0)	They're fine to use until the slots are nearly gone.
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06-14-2023, 04:00 PM	#7
sc_tr0jan_m3 Lieutenant Colonel 519 Rep 1,730 Posts Drives: 2018 Grigio Telesto F80 M3 DCT Join Date: Feb 2009 Location: Dallas, TX iTrader: (0)	No cracks don’t look back! __________________ 2018 Grigio Telesto F80 M3 DCT \| :: Bone Stock :: 2004 Titanium Silver E46 M3 6 Speed \| :: Track Car ::
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