Brake Rotor Refinishing. Pontiac Sun Runner - 2WD (Canada) 1998

For 1990-2009 cars

Do not refinish the 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 are heat spots or excessive scoring.

All 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 brake rotor that will not meet the specifications. If the rotor thickness will be less than specifications after refinishing, the rotor must be replaced. A rotor which has been refinished too thin will not have proper heat transfer capabilities.

Accurate control of the rotor tolerances is necessary for proper performance of the disc brakes. Machine the rotor only with precision equipment. Service machining equipment on a regular basis following the manufacturer's recommended maintenance procedure.

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

### Off-Vehicle Procedure

When refinishing the brake rotor off of the vehicle, locate the deepest score and 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 handwheel until the bits have cleared the inner edge of the rotor face. Adjust the micrometer knobs for approximately 0.0127 mm (0.0005 in) more than the first reading. This will ensure clearing the rotor in one cut.

The optimum speed for refinishing braking surfaces is a spindle speed of 200 RPM. Crossfeed for rough cutting should range from 0.15 to 0.25 mm (0.006 to 0.010 in) per revolution. Make finish cuts at a crossfeed no greater than 0.05 mm (0.002 in) per revolution.

It is very important that the rotor surface be made non-directional by dressing the rotor surfaces with a sanding disc power tool such as an Ammco 8350 Safe Swirl Disc Rotor Grinder, or the equivalent, using 120 grit aluminum sandpaper. Sand each rotor surface with moderate pressure for a minimum of 60 seconds. An alternate method is to use a sanding block with 150 grit aluminum oxide sandpaper. With the rotor turning at approximately 150 RPM, 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 brake cleaner.

After refinishing the rotors, replace any rotor that does not meet the following minimum thickness specifications:

• | 2-Door: 8.0 mm (0.315 in)

• | 4-Door: 15.0 mm (0.590 in)