Non-Directional
NON-DIRECTIONAL FINISHIt is very important that the rotor surface be made non-directional by finishing the rotor surfaces with a non-directional rotor finisher such as 54-433179 Non-Directional Rotor Refinisher listed in the GM Dealer Equipment Catalog, or equivalent be used.
Alternate Method
If the brake lathe is not equipped with an adequate non-directional finishing tool, an alternate method is to use a sanding block with 150 grit aluminum oxide sandpaper. With the rotor turning at the lathe manufacturer's highest recommended cutting speed, sand each rotor surface for a minimum of 60 seconds using moderate pressure. After the rotor has been sanded, clean each surface with denatured alcohol or a suitable brake cleaner. The finished rotor surface should be as close to that of a new front brake rotor as possible. Failure to obtain the best possible finish may affect braking performance.
NOTE: Front brake rotors should always be replaced if turning will result in a front brake rotor the does not meet manufacturer specifications for minimum thickness. When installing new brake rotors, do not refinish the surfaces of these parts. New brake rotors have the correct level of surface finish.