Buick Regal 1997-2000

Brake Disc (Rotor)




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.

  1. Raise and safely support the vehicle. Remove the wheel and tire assembly.
  3. 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).
  5. Install a dial indicator to the steering knuckle so that the indicator button contacts the rotor about 1 inch (25mm) from the rotor edge.
  7. Zero the dial indicator.
  9. Turn the rotor one complete revolution and observe the total indicated runout.
  11. The Total Indicated Runout (TIR) must not exceed 0.003 inch (0.080mm).
  13. 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.