Service Information

Volt

Brake Disc Refinishing

Special Tools

•	CH-41013 Disc Resurfacing Kit

•	CH-42450-A Wheel Hub Resurfacing Kit

For equivalent regional tools, refer to Special Tools .

Warning: Refer to Brake Dust Warning in the Preface section.

Note:

•	The disc brake discs do not require refinishing as part of routine brake system service. New disc brake discs do not require refinishing.

Do not refinish disc brake discs in an attempt to correct the following conditions:

--	Brake system noise - squeal, growl, groan

--	Uneven and/or premature disc brake pad wear

--	Superficial or cosmetic corrosion/rust of the disc brake disc friction surface

--	Scoring of the disc brake disc friction surface less than the maximum allowable specification

•	Before refinishing a brake disc, the disc MUST first be checked for adequate thickness to allow the disc to be refinished and remain above the minimum allowable thickness after refinish specification. Refer to Brake Disc Thickness Measurement .

Disc brake discs should only be refinished if they have adequate thickness to be refinished and if one or more of the following conditions exist:

--	Thickness variation in excess of the maximum allowable specification

--	Excessive corrosion/rust and/or pitting

--	Cracks and/or heat spots

--	Excessive blueing discolouration

--	Scoring of the disc brake disc surface in excess of the maximum allowable specification

•	Disc brake discs may need to be refinished as part of the process for correcting brake disc assembled lateral runout (LRO) that exceeds the maximum allowable specification.

Note: If the vehicle is equipped with cross-drilled discs, use a lathe with positive rake tooling. This setup requires less cutting pressure, which will result in less vibration, and a better surface finish. Also, use a vibration dampener when cutting. Otherwise, refinish according to the following instructions.

Note: Whenever the brake disc has been separated from the hub/axle flange, clean any rust or contaminants from the hub/axle flange and the brake disc mating surfaces. Failure to do this may result in increased assembled lateral runout (LRO) of the brake disc, which could lead to brake pulsation.

Using the CH-42450-A Wheel Hub Resurfacing Kit , thoroughly clean any rust or corrosion from the mating surface of the hub/axle flange.
Using the CH-41013 Disc Resurfacing Kit , thoroughly clean any rust or corrosion from the mating surface and mounting surface of the brake disc.
Inspect the mating surfaces of the hub/axle flange and the disc to ensure that there are no foreign particles or debris remaining.
Mount the brake disc to the brake lathe according to the lathe manufacturer's instructions, ensuring that all mounting attachments and adapters are clean and free of debris.
Ensure that any vibration dampening attachments are securely in place.
With the brake lathe running, slowly bring in the cutting tools until they just contact the brake disc friction surfaces.
Observe the witness mark on the brake disc. If the witness mark extends approximately three-quarters or more of the way around the brake disc friction surface on each side, the brake disc is properly mounted to the lathe.
If the witness mark does not extend three-quarters or more of the way around the brake disc, re-mount the disc to the lathe.
Following the brake lathe manufacturer's instructions, refinish the brake disc.
After each successive cut, inspect the brake disc thickness. Refer to Brake Disc Thickness Measurement .
If at any time the brake disc exceeds the minimum allowable thickness after refinish specification, the brake disc must be replaced.
After refinishing the brake disc, use the following procedure in order to obtain the desired non-directional finish:

12.1.

Follow the brake lathe manufacturer's recommended speed setting for applying a non-directional finish.

12.2.

Using moderate pressure, apply the non-directional finish:

•	If the lathe is equipped with a non-directional finishing tool, apply the finish with 120-grit aluminium oxide sandpaper.

•	If the lathe is not equipped with a non-directional finishing tool, apply the finish with a sanding block and 150-grit aluminium oxide sandpaper.

12.3.

After applying a non-directional finish, clean each friction surface of the brake disc with methylated spirit, or an equivalent approved brake cleaner and wipe each friction surface using a clean workshop towel to remove metal particles remaining from machining. Repeat the cleaning process if necessary to remove all metal particles.

Remove the brake disc from the brake lathe.
Measure the assembled LRO of the brake disc to ensure optimum performance of the disc brakes. Refer to Brake Disc Assembled Lateral Runout Measurement .
If the brake disc assembled LRO measurement exceeds the specification, bring the LRO to within specifications. Refer to Brake Disc Assembled Lateral Runout Correction .