Brake Lathe Calibration Procedure

BENCH-TYPE LATHE

Use the following procedure to calibrate a Bench-type brake lathe:

1. After refinishing a rotor, loosen the arbor nut and while holding the inside bell clamp to keep it from rotating, rotate the rotor 180 degrees.

2. Retighten the arbor nut and set the dial indicator on the rotor using the same instructions as checking the run out on the vehicle.

3. Rotate the arbor and read the runout.

4. Divide the reading by two and this will give you the amount of runout the lathe is cutting into the rotor.

Important:
If there is any runout, you will need to machine the inside bell clamp in place on the lathe (this procedure is for a Bench-type lathe ONLY. DO NOT machine inside the bell clamp on an On-Car type lathe).

Machining the Inside Bell Clamp (Bench-Type Lathe Only)

Any nicks or burrs on the shoulder of the arbor must be removed. An 80-grit stone can be used to accomplish this. Spray WD-40(R) on the shoulder and with the lathe running, hold the stone flat against the shoulder surface using slight pressure. When the burrs are gone, clean the surface. Burrs must also be removed from the hub of the inside bell clamp. This can be accomplished with the stone and WD-40(R). Keep the stone flat on the hub while removing the burrs. After removing the burrs, clean the hub.

Place the bell clamp on the arbor of the lathe and use the small radius adapters first and then spacers to allow you to tighten the arbor nut to secure the bell clamp to the lathe. Position the tool bit in the left hand of the rotor truer so you can machine the face of the bell clamp. Machine the face of the bell clamp taking just enough off of it to cut the full face of the clamp the full 360 degrees. Before you loosen the arbor nut, match mark the hub of the bell clamp to the arbor and line up these marks before machining a rotor. A magic marker can be used to make the match marks. Machine a rotor and recheck the calibration. Repeat this procedure on all Inside Bell Clamps used.

Important:
If runout is still present, contact the brake lathe supplier.