Quote:
Originally Posted by RZNT4R
It is likely to be rust from a wet rotor transferring to the pad and dripping down on the rack.
Btw, the rust on the hub is horrific. Wheel hubs should be spotlessly clean and receive a thin coat of high temp grease to prevent rust from setting back in (I like either lithium grease or the permatex silicon-ceramic orange stuff, gray anti-seize goes on too thick and dries out too fast). Rust scales on a hub almost always put you out of spec for lateral runout on the rotor and are a frequent cause of wheel tightening issues.
But you have more pressing issues: one of the piston dust boots visible in your pic seems torn, and the friction material on the pad turning white is a sign the pad is being massively overheated, I usually see pads that color when I service neglected brakes that are totally seized. The fingers on the outer side of the caliper are also starting to change color, there is way too much heat being put into these brakes.
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The rust could certainly explain the color. However, I think it's more than just water runoff here. I live in a very dry area (High Desert of Southern California), and the residue was for sure oily. If it were just water run-off, it would be dry and flaky like the rest of the components.
Thanks for that. I clean the hubs with wire brush and put antiseize on them when I can. The rust is unavoidable simply due to heat and enclosed environment. Wheel cleaner probably doesn't help either. I'll try a thicker grease and perhaps touch up with primer.
These see the track regularly, and that's the price to be paid. My pads (race pads meant to see the heat) always get their lettering seared off after the first outing. My friends were reporting the rotors were glowing faint red in the day time. The piston boots will never survive in that kind of environment. The pads work fine and still bite like they were new. There isn't anything more I can really do to help that other than take longer time cooling the car down and add temperature monitoring tape