Manufacturers use brake hardware to help with component fitment, reduce noise and vibration and also help reduce component movement friction. Precise dimensions and smooth edge surfaces free of rust and well lubricated will allow the moving surfaces to glide across the slipper, hardware, backing plate and caliper, thus eliminating noise. Brake hardware is subjected to the same environment as the brake pads and rotors and should be replaced with every brake service.
Machined rotors should be washed with a mild dish washing detergent and hand brush prior to installing new brake pads. This process removes machining debris left on the surface of the rotor from the machining process. Failure to properly wash the machined rotors can result in damage to the friction material on the new pad and additional vibration and noise.