Thread: New Rotors
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      01-03-2013, 07:26 PM   #9
mlhj83's Avatar
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Drives: '11 E92 M3 DCT ZCP
Join Date: Aug 2011
Location: London

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Originally Posted by M3PO
Originally Posted by mlhj83 View Post
I use BMW M Sport pads and I've driven them to the point of absolute fade and have never had vibration under braking. I did however have significant vibration under braking when I tried the standard pads on track, which gradually disappeared (2 weeks after track day) as the uneven pad transfer wore off.

I'm inclined to think that yours is also due to uneven pad transfer. It's not something you can easily see. I'm fairly certain that most pads would overheat way before the OEM discs go beyond its maximum operating temperature. Also, once a disc is truly warped - not with axial runout due to pad deposits - it'll never recover, so by the fact that it gets better as you manage the brakes before the next session, points more towards uneven pad transfer.
So if I follow you, you think I was over heating the pads, getting some uneven transfer, and then the easier laps were removing it?
Yes. Just be aware that uneven pad transfer can become permanent if you keep hammering the brakes, as the parts of the disc with pad deposits get hotter and hotter with each pass of the brake pad; more so than the parts of the disc with no deposits.

OEM pads take some time to scrub off deposits because the pads are generally quite soft and not very abrasive. Also, in general, pads are at their most abrasive when cold to slightly warm temperatures.