For proper braking, the rotor should be serviced within allowable limits whenever you replace your
Brake Pads. Should the rotor be severely scarred, twisted or when braking causes pedal pulsation or roughness, it needs to be remachined on the vehicle using a hub-mounted tool or changed out with a new one. This way works well to keep runout down, since it grooves the rotor to the hub and bearing. You will find minimum thickness markings on all rotors at an un-machined section, indicating how thin the brake rotor can be machined. It is significant that rotor thickness should not be machined below the minimum given limit. Check for chips, rust or debris on the rotor face and hub adapters before you fit any new brake parts. As you work on the lathe, be sure to read the operating manual often and machine both sides at the same time, to ensure the rotor does not get a tapered or uneven result. When refacing, make sure the Total Indicator Reading (TIR) stays at 0.08 mm (0.003 inch) and the thickness variation is less than 0.013 mm (0.0005 inch), so caution is needed when turning the rotor.