Brake Rotor Assembled Lateral Runout (LRO) Measurement

FRONT ROTOR

^ Tools Required
- J 8001 Dial Indicator Set

Lateral runout is the movement of the rotor braking surface from side to side as it rotates on the front bearing hub, this could be described as ROTOR WOBBLE. The movement of the rotor from side to side in the lateral plane knocks the pads away from the rotor. This cause the piston to be driven back into its bore. This can result in excessive pedal travel and possible vibrations during braking.

1. Remove the front brake caliper.
2. Install the wheel bolt (2) to rotor opposite rotor set screw (1) so the rotor is held tight against the hub.





3. Fasten J 8001 to the steering knuckle so that the indicator button contacts the rotor surface about 13 mm (0.5 inch) from the outer edge.
4. Zero J 8001.
5. Move the rotor one complete revolution and observe the Total Indicted Runout (TIR).
^ TIR should not be more than 0.10 mm (0.004 inch).
^ A brake rotor that does not meet the lateral runout specification should be resurfaced or replaced as necessary.

6. Install the brake caliper.

REAR ROTOR

^ Tool Required
- J 8001 Dial Indicator Set





1. Remove the brake caliper.
2. Install the wheel bolt (1) onto the rotor opposite the rotor set screw so the rotor is held tight against the hub.





3. Fasten the J 8001 to the rear brake caliper housing so that the indicator button contacts the rotor surface about 13 mm (0.5 inch) from the edge of the rotor.
4. Push in the wheel bearing hub to minimize endplay while setting the J 8001 to zero.
5. Push in the wheel bearing hub to minimize wheel bearing hub endplay while turning the rotor one complete revolution.
6. Observe the Total Indicated Runout (TIR). The TIR should not be more than 0.10 mm (0.004 inch).
7. Check the wheel bearing hub flange for excessive lateral runout or for looseness if the lateral runout of the rotor still exceeds 0.10 mm (0.004 inch).
8. Install the brake caliper.