Caution: Refer to Safety Glasses Caution in the Preface section.
Caution: Refer to Vehicle Lifting Caution in the Preface section.
Caution: Refer to Brake Dust Caution in the Preface section.
Important:
• The brake discs do not require refinishing as part of routine brake system
service. NEW brake discs do not require refinishing. • DO NOT refinish brake discs in an attempt to correct the following conditions: - Brake system noise - squeal, growl, groan - Uneven and/or premature brake pad wear - Superficial or cosmetic corrosion/rust of the brake disc friction surface - Scoring of the brake disc friction surface less than the maximum allowable
specification • Before refinishing a brake disc, the brake disc must first be inspected
for adequate thickness to allow the brake disc to be refinished and remain above the
minimum allowable thickness after refinish specification. Refer to
Brake Rotor Thickness Measurement. • 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. - Too much corrosion/rust and/or pitting. - Cracks and/or heat spots. - Too much blueing, discoloration. - Scoring of the brake disc surface in excess of the maximum allowable specification. • 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.
- Clean any rust or corrosion from the mating surface of the hub/axle flange.
- 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 brake disc to make sure 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.
- Make sure 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 correctly 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 brake 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 Rotor 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:
- Remove the brake disc from the brake lathe.
- Measure the assembled LRO of the brake disc to make sure optimum performance of the disc brakes. Refer to Brake Rotor Assembled Lateral Runout Measurement.
- If the brake disc assembled LRO measurement exceeds the specification, bring the LRO to within specifications. Refer to Brake Rotor Assembled Lateral Runout Correction.
Important: 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 LRO of the brake disc, which may lead to brake pulsation.
| 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 aluminum oxide sandpaper. |
| • | If the lathe is not equipped with a non-directional finishing tool, apply the finish with a sanding block and 150 grit aluminum oxide sandpaper. |
| 12.3. | After applying a non-directional finish, clean each friction surface of the brake disc with denatured alcohol, or an equivalent approved brake cleaner. |
