Brake Rotor Refinishing Accu Turn

You do not need to refinish brake rotors when doing routine brake maintenance such as replacing worn brake pad assemblies. Refinish brake rotors only under the following circumstances:

Brake rotors have a minimum thickness dimension cast into them. This dimension is the minimum wear dimension and not a refinish dimension. Do not use a rotor that will not, after refinishing, meet the specifications shown on the brake rotor. Always replace the rotor with a new rotor. It may be necessary to replace the brake rotors in pairs in order to assure an even braking balance on both wheels.

Accurate control of brake rotor tolerance is necessary for the proper performance of disc brakes. Machining should be done only with precision equipment. Service the machining equipment on a regular basis following the manufacturer's recommended maintenance procedures.

When refinishing brake rotors, make sure the attaching adapters, the tool holders, the vibration dampeners, and the tool bits are in good condition. Always use sharp cutting tools or bits. Use only the replacement cutting bits recommended by the equipment manufacturer. Dull or worn tools leave a poor surface finish that will affect braking performance. Always use vibration dampening attachments when refinishing braking surfaces. These attachments eliminate tool chatter in order to allow for a better surface finish. Make sure these adapters are clean and free of nicks.

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

It is very important that you make the brake rotor surface non-directional. Dress the brake surfaces with a sanding disc tool such as the Ammco 8750 Safe Swirl Disc Rotor Grinder, Accu Turn 433179 Non-Directional Swirl Finisher, or equivalent. Use 120 grit aluminum oxide sandpaper.

Standard Method

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

Sand each brake rotor surface using moderate pressure for a minimum of 60 seconds.

Alternate Method

If the brake lathe is not equipped with an adequate non-directional finishing tool, use a sanding block with 150 grit aluminum oxide sandpaper.

1. Run the brake rotor at the equipment manufacturer's highest recommended cutting speed.

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

2. Sand each brake rotor surface using moderate pressure for a minimum of 60 seconds.

1. Mount the brake rotor to the brake lathe. Refer to the brake lathe manufacturer's recommended procedure.
2. Locate the deepest score and turn the micrometer knobs until the tool bit bottoms out at the deepest point of the score.
3. Zero the scale.
4. Back out the tool bits.
5. Advance the cutter hand-wheel until the bits have cleared the inner edge of the brake rotor face.
6. Adjust the micrometer knobs for approximately 0.0127 mm (0.005 in) more than the first reading. This will ensure clearing the brake rotor in one cut.
7. Perform one cut procedure. For refinishing information, refer to the Brake Lathe Specifications table.
8. Perform swirl refinishing to the brake rotor. Refer to Brake Rotor Refinishing .
9. Remove the brake rotor from the brake lathe.
10. Clean the brake rotor using Brake Parts Cleaner GM P/N 12345754 or equivalent.

1. Mount the brake rotor to the brake lathe. Refer to the brake lathe manufacturer's recommended procedure.
2. Locate the deepest score.
3. Turn the brake rotor micrometer knobs until the tool bit bottoms out at the deepest point of the score.
4. Zero the scale.
5. Back out the tool bits.
6. Advance the cutter hand-wheel until the bits have cleared the inner edge of the brake rotor face.
7. Perform rough and finish cuts. For refinishing information, refer to Brake Lathe Specifications .
8. Perform swirl refinishing to the brake rotor. Refer to Brake Rotor Refinishing .
9. Remove the brake rotor from the brake lathe.
10. Clean the brake rotor using Brake Parts Cleaner GM P/N 12345754 or equivalent.

Brake Rotor Refinishing Ammco

You do not need to refinish brake rotors when doing routine brake maintenance such as replacing worn brake pad assemblies. Refinish brake rotors only under the following circumstances:

Brake rotors have a minimum thickness dimension cast into them. This dimension is the minimum wear dimension and not a refinish dimension. Do not use a rotor that will not, after refinishing, meet the specifications shown on the brake rotor. Always replace the rotor with a new rotor. It may be necessary to replace the brake rotors in pairs in order to assure an even braking balance on both wheels.

Accurate control of brake rotor tolerance is necessary for the proper performance of disc brakes. Machining should be done only with precision equipment. Service the machining equipment on a regular basis following the manufacturer's recommended maintenance procedures.

When refinishing brake rotors, make sure the attaching adapters, the tool holders, the vibration dampeners, and the tool bits are in good condition. Always use sharp cutting tools or bits. Use only the replacement cutting bits recommended by the equipment manufacturer. Dull or worn tools leave a poor surface finish that will affect braking performance. Always use vibration dampening attachments when refinishing braking surfaces. These attachments eliminate tool chatter in order to allow for a better surface finish. Make sure these adapters are clean and free of nicks.

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

1. Mount the brake rotor to the brake lathe. Refer to the brake lathe manufacturer's recommended procedure.
2. Locate the deepest score.
3. Turn the brake rotor micrometer knobs until the tool bit bottoms out at the deepest point of the score.
4. Zero the scale.
5. Back out the tool bits.
6. Advance the cutter hand-wheel until the bits have cleared the inner edge of the brake rotor face.
7. Perform rough and finish cuts. For refinishing information, refer to Brake Lathe Specifications .
8. Perform swirl refinishing to the brake rotor. Refer to Brake Rotor Refinishing .
9. Remove the brake rotor from the brake lathe.
10. Clean the brake rotor using Brake Parts Cleaner GM P/N 12345754 or equivalent.

Brake Rotor Refinishing Non-Directional Refinishing

It is very important that you make the brake rotor surface non-directional. Dress the brake surfaces with a sanding disc tool such as the Ammco 8750 Safe Swirl Disc Rotor Grinder, Accu Turn 433179 Non-Directional Swirl Finisher, or equivalent. Use 120 grit aluminum oxide sandpaper.

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

Sand each brake rotor surface using moderate pressure for a minimum of 60 seconds.

If the brake lathe is not equipped with an adequate non-directional finishing tool, use a sanding block with 150 grit aluminum oxide sandpaper.

1. Run the brake rotor at the equipment manufacturer's highest recommended cutting speed.

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

2. Sand each brake rotor surface using moderate pressure for a minimum of 60 seconds.