For 1990-2009 cars only
| Important: It is not necessary to refinish the brake rotors when replacing the brake shoe and lining pads assemblies. |
| • | Refinish the brake rotors only under the following conditions: |
| - | The brakes are pulsating. |
| - | The brake rotor has hot spots. |
| - | The brake rotor is scored greater than 1.5 mm (0.060 in). |
| • | The brake rotors have a minimum thickness cast into them. This is the minimum wear dimension and not a refinish dimension. Replace a brake rotor that will not meet the specified dimensions after refinishing. Refer to Rotor Thickness Specifications . A rotor that is too thin will not have the proper heat transfer capabilities. |
| • | The proper performance of disc brakes requires accurate control of rotor tolerances. |
| • | Use only precision equipment in machining. |
| • | Regularly service the machine equipment, using the manufacturers' recommended procedures for maintenance. |
| • | When refinishing rotors, do the following: |
| • | Make sure that all tools, adapters, holders, vibration dampeners, and tool bits are in good condition. |
| • | Use sharp cutting tools and tool bits. Dull or worn tools leave a poor surface finish that affects initial brake performance. |
| • | Use replacement cutting tool bits the equipment manufacturer recommends. |
| • | Use only vibration-dampening attachments while refinishing brake surfaces. These eliminate tool chatter, thereby promoting a better finish. |
| • | Make sure the adapters are clean and free of nicks. |
| • | The Ammco Brake Lathe and the Accu Turn Lathe (GM dealer equipment) are recommended off-vehicle brake drum and brake rotor lathes that achieve good results. Refer to Brake Lathe Specifications or Brake Lathe Specifications . If any other lathe is used, follow the manufacturer's instructions and recommendations. |
| • | Make the brake rotor surface non-directional. |
| • | Dress the brake rotor surfaces with a sanding disc power tool using 120 grit aluminum oxide sandpaper. Use a tool such as the Ammco 8350 Safe Swirl Brake Rotor Grinder. |
| • | Sand each brake rotor surface using moderate pressure for at least 60 seconds. As an alternate method, use a sanding block with 150 grit aluminum oxide sandpaper. |
| • | With the brake rotor turning at about 150 RPM, sand each brake rotor surface using moderate pressure for at least 60 seconds. |
| • | Clean each brake rotor surface with denatured alcohol or a substitute cleaner after sanding. |
Refinishing Procedure
- Locate the deepest score in the brake rotor. Turn the rotor micrometer knobs until the tool bit bottoms out at the deepest point of the score.
- Zero the scale and back out the tool bits.
- Advance the cutter hand-wheel until the bits have cleared the inner edge of the brake rotor face.
- Adjust the micrometer knobs about 0.0127 mm (0.005 in) more than the first reading. This will ensure clearing the brake rotor in one cut.
- 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 initial braking performance.
