Warped Rotors
08-14-2021, 04:16 PM
#2
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‘24 BMW iX M60
You mention 'warped rotors', then ask about the GTR.
Can you give us more detail?
Why?: because rotors almost never actually 'warp' they simply get uneven deposits of brake pad material on them that then appears to make them act as if they aren't balanced. Dealers love to tell you your rotors are warped so that they can make you pay out of your butt for new rotors when all the existing rotors need is to be 'cleaned' off.
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Acta_Non_Verba (08-14-2021)
08-14-2021, 06:37 PM
#4
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Bentley Continental GT; AMG GT
VERY unlikely they're warped unless you were aggressively tracking, then it is a very small possibility under unusual conditions. In all my experience warping just never happens on street cars...even aggressively driven on the streets. If a dealer said that to me I'd say something like "thanks" and leave.
If you've done any experimenting with pad composites, some cheaper pads out there will leach resin onto the rotors and, as bishman said, the resin deposits onto the rotors and can give a "slip/grab" feel that can be misdiagnosed as warp.
I've actually put a dial indicator on rotors to prove to some in the past, that the rotor ran true when they were told the rotors were warped. Frankly, never had one actually warped.
Last edited by Acta_Non_Verba; 08-14-2021 at 06:42 PM.
08-14-2021, 08:28 PM
#5
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‘24 BMW iX M60
Try this: go to a deserted road; get the car up to around 60 mph and then brake as hard as you can without engaging the ABS. Do NOT come to a complete stop; start accelerating again when you get to say 5 mph. Let the rotors cool down by driving for a few minutes without touching the brakes. Then rinse and repeat the above but at a higher speed, say 80 mph.
Do the above around 5 times and make sure you let the rotors cool before coming to a complete stop.
NB: the above assumes that you have the OEM brake pads installed, and not some ‘ceramic non-dusting’ type of aftermarket pad installed.
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08-15-2021, 11:22 AM
#6
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Bentley Continental GT; AMG GT
I’m assuming you have the iron rotors on your GTR?
Try this: go to a deserted road; get the car up to around 60 mph and then brake as hard as you can without engaging the ABS. Do NOT come to a complete stop; start accelerating again when you get to say 5 mph. Let the rotors cool down by driving for a few minutes without touching the brakes. Then rinse and repeat the above but at a higher speed, say 80 mph.
Do the above around 5 times and make sure you let the rotors cool before coming to a complete stop.
NB: the above assumes that you have the OEM brake pads installed, and not some ‘ceramic non-dusting’ type of aftermarket pad installed.
Try this: go to a deserted road; get the car up to around 60 mph and then brake as hard as you can without engaging the ABS. Do NOT come to a complete stop; start accelerating again when you get to say 5 mph. Let the rotors cool down by driving for a few minutes without touching the brakes. Then rinse and repeat the above but at a higher speed, say 80 mph.
Do the above around 5 times and make sure you let the rotors cool before coming to a complete stop.
NB: the above assumes that you have the OEM brake pads installed, and not some ‘ceramic non-dusting’ type of aftermarket pad installed.
08-15-2021, 03:17 PM
#7
And for carbon-ceramic rotors, I've attached the AMG-recomended bed-in that was posted on the private lounge forum some number of years ago.
FWIW, I was able to get some pre-trackday plating on my CCBs with TiKT race pads and cooling ducts (GTR Pro) without being quite so aggressive. I did 10x "1G brake from 120 kph down to 20 kph then accelerate hard back to 120 and repeat immediately" sessions then kept running for the brakes to cool completely (which happens quickly with the brake-cooling ducts). After a track day, they're now nicely plated. #;-)
FWIW, I was able to get some pre-trackday plating on my CCBs with TiKT race pads and cooling ducts (GTR Pro) without being quite so aggressive. I did 10x "1G brake from 120 kph down to 20 kph then accelerate hard back to 120 and repeat immediately" sessions then kept running for the brakes to cool completely (which happens quickly with the brake-cooling ducts). After a track day, they're now nicely plated. #;-)
