For 1990-2009 cars

## Brake Rotor Refinishing Front

Important: DO NOT refinish brake rotors when performing routine brake maintenance, such as replacing worn disc brake pads. Refinish a rotor ONLY under the following circumstances:

• | There is a complaint of brake pulsation.

• | There is scoring greater than 1.5 mm (0.060 in).

All brake rotors have a minimum thickness dimension cast into the rotor. This dimension is not a minimum refinishing dimension. The minimum refinishing dimension is larger than the discard dimension. Do not use a brake rotor that, after refinishing, will not meet the minimum thickness shown on the rotor. Replace it with a new rotor. Refer to Component Specifications .

Accurate control of the rotor tolerance is necessary for proper performance of the disc brakes. Machine the rotor using precise equipment. Service machining equipment on a regular basis. Follow the manufacturer's recommended maintenance procedure.

Ensure that the following tool accessories are in good condition when refinishing the rotors:

• | The attaching adapters

• | The tool holders

• | The vibration dampeners

• | The tool bits

Always use sharp cutting tools and bits. Replace cutting bits using equipment recommended by the manufacturer. Dull or worn tools leave a poor surface finish which will affect braking performance. Always use anti-chatter silencer attachments when refinishing braking surfaces. The attachments eliminate tool chatter and will result in a better surface finish. Ensure that the adapters are clean and free of nicks.

In order to correct brake pulsation, refinish the rotors using an on-vehicle brake lathe. Follow the equipment manufacturer's recommended specifications and procedure.

Important: Remove any rust and scale from the rotor and spindle hub mating surfaces. Failure to do so may introduce excessive lateral runout when the rotor is mounted on the brake lathe, or when the rotor is reinstalled on the spindle hub.

The following two procedures are recommended and achieve adequate results using two different off-vehicle disc brake lathes. If any other lathe is used, follow that lathe's instructions and recommendations:

### Accu Turn® Brake Lathe

1. Locate the deepest score and turn the rotor micrometer knob until the tool bit bottoms out at the deepest point of the score.
2. Zero the scale and back out the tool bit.
3. Advance the cutter handwheel until the bits have cleared the inner edges of the rotor face.
4. Adjust the micrometer knobs for approximately 0.127 mm (0.005 in) more than the first reading. Use this method in order to resurface the rotor in one cut.

#### Front Rotor Finish Cut

Spindle Speed | 105 rpm
Depth of Cut | As necessary
Cross Feed (per rev.) | 0.08 mm (0.003 in)
Vibration Dampener | Yes

### 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.

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.

After the rotor has been sanded, clean each surface with denatured alcohol or a suitable brake cleaner.

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.

## Brake Rotor Refinishing Rear

Important: DO NOT refinish brake rotors when performing routine brake maintenance, such as replacing worn disc brake pads. Refinish a rotor ONLY under the following circumstances:

• | There is a complaint of brake pulsation.

• | There is scoring greater than 1.5 mm (0.060 in).

All brake rotors have a minimum thickness dimension cast into the rotor. This dimension is not a minimum refinishing dimension. The minimum refinishing dimension is larger than the discard dimension. Do not use a brake rotor that, after refinishing, will not meet the minimum thickness shown on the rotor. Always use a new rotor. Refer to Component Specifications .

Accurate control of the rotor tolerance is necessary for proper performance of the disc brakes. Machine the rotor using precise equipment. Service the machining equipment on a regular basis. Follow the manufacturer's recommended maintenance procedure.

Ensure that the following tool accessories are in good condition when refinishing the rotors:

• | The attaching adapters

• | The tool holders

• | The vibration dampeners

• | The tool bits

Always use sharp cutting tools and bits. Replace cutting bits using equipment that is recommended by the manufacturer. Dull or worn tools leave a poor surface finish which will affect braking performance. Always use anti-chatter silencer attachments when refinishing braking surfaces. The attachments eliminate tool chatter and will result in a better surface finish. Ensure that the adapters are clean and free of nicks.

In order to correct brake pulsation, refinish rotors using an on-vehicle brake lathe. Follow the equipment manufacturer's recommended specifications and procedure.

Important: Remove any rust and scale from the rotor and spindle hub mating surfaces. Failure to do so may introduce excessive lateral runout when the rotor is mounted on the brake lathe, or when the rotor is reinstalled on the spindle hub.

The following two procedures are recommended and achieve adequate results using two different off-vehicle disc brake lathes. If any other lathe is used, follow that lathe's instructions and recommendations:

### Accu Turn® Brake Lathe

1. Locate the deepest score. Turn the rotor micrometer knob until the tool bit bottoms out at the deepest point of the score.
2. Zero the scale and back out the tool bit.
3. Advance the cutter handwheel until the bits have cleared the inner edges of the rotor face.
4. Adjust the micrometer knobs for approximately 0.127 mm (0.005 in) more than the first reading. Use this method in order to resurface the rotor in one cut.

Rough Cut | Finish Cut
--- | ---
Spindle Speed | 105 rpm
Depth of Cut | As necessary
Cross Feed (per rev.) | 0.08 mm (0.003 in)
Vibration Dampener | Yes

### Rotor Mounting Adapter

#### Tools Required

• | J 37160-A Rotor Mounting Adapter

• | J 37160-50 Rotor Mounting Adapter Sleeve

Important: Verify that the mounting surfaces of these components are clean and free from nicks, burrs or rust.

1. Inspect all of the mounting hardware for the following conditions:

• | Rust

• | Nicks

• | Dirt

• | Abnormal wear

• | For proper results, ensure that all components are in good condition and clean.

2. Inspect the rotor:

• | Measure the lateral runout. Refer to Brake Rotor Lateral Runout Check .

• | Measure the thickness variation. Refer to Brake Rotor Thickness Variation Check .

• | Ensure that the mounting surface of the rotor is clean and free from rust and nicks.

3. Mount the J 37160-A on a spindle arbor.

• | Use a suitable combination of spacers or collets in order to tighten the J 37160-A to the arbor.

• | When using lathes with a 7/8-inch spindle arbor, use the J 37160-50 with the J 37160-A .

• | The J 37160-50 is not required with lathes using a 1-inch spindle arbor.

Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

4. Mount the rotor onto the J 37160-A

• | Mount the clamp plate to the rotor using the enclosed bolts/screws.

• | The rotor may be installed and removed while the J 37160-A is mounted on the machine spindle.

Tighten
Tighten the rotor mounting adapter nuts in a cross pattern to 34 N·m (23 lb ft).

5. Install the anti-chatter silencer onto the rotor.
6. Set the spindle speed to approximately 150 RPM (or mid-range).
7. While the machine is running, bring the tool bit up and touch off.

• | Stop the machine.

• | Inspect the witness mark. If the witness mark goes ¾ of the way around, the rotor is mounted properly.

• | Continue turning the rotor using normal methods in order to resurface the rotor.

8. If the witness mark does not go ¾ of the way around, repeat the above steps.

### 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.