Does anyone know if this is normal? Did a track day today. What is this substance flaking off?

 

It's a little hard to tell from the pics, but it looks like some paint coming off the rotor's hat. I don't know if your R58 rotors were painted white, or if the paint discolored with heat, but as long as the surface of the rotor is fine and not warped, they are good.

All rotor hats rust (as do surfaces if the car is not driven for a while), and higher end rotors pre-emptily paint them. Either way, it's a cosmetic consideration that has to effect on braking efficiency.

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Excellent thanks for the answer. I am *finally* getting time to swap pads today. I am taking a closer look and I will post pics when done.

 

Ok finally did some investigation. Seems that I disintegrated my dust boots (I think) and possibly the backing of the brake pad? maybe cooked anti-squeal compound too? Dunno. Pads look fine. The crap finish on the rotor seems to have been compromised too. I don't care because I didn't have any fade at all. Mission accomplished!

 

Pads are fine, but the paint has warped off the backing plates. No big deal.
Add some more anti-rattle goop to the back of the pads, and put them back in.

Many pads manufacturers throw a few packets in with the pads.
If you don't have extras lying around, add this one to your next parts order from BavAuto (or similar):
http://www.bavauto.com//assets/produ...f4oz_img01.jpg

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Thanks for the tip. I took the hawk hp+ pads back out of the brakes and stuck the oem pads back in today. Also for anyone the arrow on the back side of the OEM pads indicates the direction the wheel rotates. I put them on backwards on the driver's side and notice the directional nature on the passenger side so I had to take the driver's side ones out again haha.