OrbitalEllipses
Ultimate Member
I painted my Audi S4's brakes in red, and ran probably 20 track days in it. Went through 3 sets of rotors and pads. They turned pink probably 3-4 years later. Probably from the age of the paint. I am not saying it doesn't happen, but I haven't seen it, not that I go looking for it. Maybe the brown is from brake dust
STI calipers are gold painter, EVO calipers are red...both turn a brownish color. Perhaps it's the underlying construction - they use the same basic Brembo caliper shape from what I understand.
If your S4 has Alcons, well that's a radically different caliper than an OEM EVO/STI 4pot Brembo. Your picture looks like a forged monobloc, bridged caliper with significant cooling slots.