Nondirectional Finishing

Ensure that the rotor surface is nondirectional by dressing the rotor surfaces. Use a non-directional rotor finisher such as the 54-433179 Non-Directional Rotor Refinisher listed in the GM Dealer Equipment Catalog, or a suitable equivalent.
If the brake lathe is not equipped with an adequate nondirectional finishing tool, use a sanding block with 150 grit aluminum oxide sandpaper.
After the rotor has been sanded, clean each surface with denatured alcohol or a suitable brake cleaner.
With the rotor turning at the equipment manufacturer's highest recommended cutting speed, sand each rotor surface for a minimum of 60 seconds using moderate pressure.

Important: Replace any rotor that does not meet the minimum thickness specification recommended by the manufacturer. Do not resurface new brake rotors. New brake rotors are manufactured with the proper surface finish.

The finished rotor surface should be as close as possible to that of a new rotor. Failure to obtain the best possible rotor finish may affect braking performance.