Sorry to bump, but I just took my 135 to Laguna Seca last weekend. I had upgraded to stainless steel brake lines, Motul fluid, and Hawk HT-10 race pads, as I've had a history of atrocious fade and actually BENT brake pads on my old E36 there.
Well, lo and behold I have discolored calipers, slightly yellow/greenish tint to them. I haven't swapped back to stock pads yet and don't have access to a home garage to do the swap myself for a few months. What's the likelihood I toasted my whole brake system, and will need to do a total caliper rebuild?
I did drive about 350 miles of highway/street after the track day, and haven't had any noticeable issues, except that the first time I press the brake after a dead cold startup I hear a small metallic popping sound, and then not again until the next day on a dead cold start. Is this likely to be a safety issue if I melted dust seals/discolored calipers/possibly cracked a piston?
Dunno what the best solution is to this aside from not tracking the 135, as I don't want to spring for a BBK. Sigh.
In any case, the damage might already be done...