GM recommends that the best way to check lateral runout is with the wheels still installed on the vehicle. This gives a much more accurate reading of the Total Indicated Runout (TIR) under real braking conditions. If equipment is not available to perform the check with the wheels installed, the next best reading can be made with the wheels removed but with the caliper still installed.
- Raise and safely support the vehicle. Remove the wheel and tire assembly.
- It is important that, since the wheel has been removed, that the brake rotor be properly retained. Install the wheel lug nuts (some technicians install them backwards to present a flat face to the rotor, depending on the design of the lug nut). Torque them just as if the wheel were installed to 100 ft. lbs. (140 Nm).
- Install a dial indicator to the steering knuckle so that the indicator button contacts the rotor about 1 inch (25mm) from the rotor edge.
- Zero the dial indicator.
- Turn the rotor one complete revolution and observe the total indicated runout.
- The Total Indicated Runout (TIR) must not exceed 0.003 inch (0.080mm).
- If the TIR exceeds specifications, have the rotor refinished or replaced.
Please note that in some cases, excessive lateral runout of the rotor can be improved by indexing the rotor on the hub, one or two bolt positions from the original position. If the lateral runout cannot be corrected by indexing the rotor, remove the rotor and check the wheel hub for excessive lateral runout or looseness (perhaps the wheel bearings are worn). If the hub lateral runout exceeds 0.0015 inch (0.040 mm), then replace the hub. If the lateral runout of the hub is within specifications, then rotor will have to be refinished at an automotive machine shop or replaced with a new part.
Removal & Installation
- Check to be sure that the park brake is released.
- Raise and support the vehicle.
- Remove the tire and wheel assembly.
- Remove the brake caliper and the caliper mounting bracket as an assembly from the suspension knuckle and support the assembly with heavy mechanic's wire, or equivalent. Ensure that there is no tension on the hydraulic brake flexible hose.
- Matchmark the position of the brake rotor to the wheel studs.
- Remove the brake rotor mounting screws.
- Remove the brake rotor. Do not force the rotor off. If the rotor is difficult to remove, ease it off by gently rotating it as you pull outward.
- Thoroughly clean any rust or corrosion from the mating surface of the hub/axle flange.
- Thoroughly clean any rust or corrosion from the mating surface and mounting surface of the brake rotor.
- Inspect the mating surfaces of the hub/axle flange and the rotor to ensure that there are no foreign particles or debris remaining.
- If installing a new brake rotor, adjust the clearance of the parking brake shoe to the drum-in-hat portion of the brake rotor.
- Install the brake rotor to the hub/axle flange. Use the matchmark made prior to removal for proper orientation to the flange.
- Install the brake rotor mounting screws and tighten to 123 inch lbs. (14 Nm).
- Install the brake caliper and the brake caliper bracket as an assembly to the suspension knuckle.
- Install the tire and wheel assembly.
- Lower the vehicle.