I like many others also had the rust on the drum part of the rear brakes, i just took the wheel off, used a wire brush and some sand paper to remove the rust, and then painted them with some black hammerite smooth, i don't see the need to use high temperature paint on that part of the brake as it shouldn't get so hot. Cheap, effective, and looks 100 times better, i also painted the caliper while i was there :)