Use the hub cleaning kit (J 42450-A) to clean the
Wheel Bearing and hub, making sure you get rid of rust and foreign material on the surface that could cause lateral runout or brake pulsation when refinishing brake rotors. Use a micrometer to find out where the rotor is the thinnest. When the rotor is thinner than what is allowed, install a new rotor instead of trying to refinish it. Use the rotor resurfacing kit (J 41013) to make sure all rust is removed from the brake rotor flange, then proceed with refinishing the rotor by following your brake lathe's operating instructions. Getting an ideal surface on the rotors is key to having good brake performance. Once the rotor has been machined, smooth it with 120-grit aluminum oxide sandpaper in a non-directional pattern and, if you can, use a non-directional rotor finisher too. Make sure to clean the brake surfaces with gm p/n 12377981 or another equivalent brake parts cleaner.