Important: Do NOT refinish the brake rotors in order to correct any of the following complaints:

Notice: Whenever the brake rotor has been separated from the wheel bearing flange, clean any rust or foreign material from the mating surface of the rotor and flange with the J 42450 hub cleaning kit. Failure to do this may result in increased lateral runout of the rotor and brake pulsation.

Remove the brake rotor.

Notice: Do not allow components to hang from the flexible brake hoses as damage to the hoses may occur. Some brake hoses have protective rings or covers to prevent direct contact of the hose with other chassis parts. Besides causing possible structural damage to the hose, excessive tension could cause the hose rings to move out of their proper locations.

Notice: Do not refinish parking brake drum surface of rotor. Refinishing will result in reduced performance of parking brake.

The following two procedures are recommended and achieve adequate results using two different off-vehicle disc brake lathes. If any other lathe is used, follow that lathe's instructions and recommendations:

Refer to the manufacturer's instructions for all initial setup and cutting procedures.

GM Dealer Equipment (One Cut Refinishing Procedure)

Refer to the manufacturer's instructions for all initial setup and cutting procedures.

Nondirectional Finishing

Ensure that the rotor surface is nondirectional by dressing the rotor surfaces with one of the following sanding disc tools (or equivalent) using 120 grit aluminum oxide sandpaper:

Use the following procedure for nondirectional finishing:

1. Sand each rotor surface with moderate pressure for a minimum of 60 seconds.

If the brake lathe is not equipped with an adequate nondirectional finishing tool, use a sanding block with 150 grit aluminum oxide sandpaper.

2. With the rotor turning at the equipment manufacturer's highest recommended cutting speed, sand each rotor surface for a minimum of 60 seconds using moderate pressure.
3. After the rotor has been sanded, clean each surface with denatured alcohol or a suitable brake cleaner.

The finished rotor surface should be as close as possible to that of a new rotor. Failure to obtain the best possible rotor finish may affect braking performance.

Tools Required

Notice: Whenever the brake rotor has been separated from the wheel bearing flange, clean any rust or foreign material from the mating surface of the rotor and flange with the J 42450 hub cleaning kit. Failure to do this may result in increased lateral runout of the rotor and brake pulsation.

1. Inspect all the mounting hardware for the following conditions:

•

Rust

•

Nicks

•

Dirt

•	Abnormal Wear

•	Ensure that all components are clean and in good condition.

2. Inspect the rotor. Ensure that the mounting surface is clean and free of nicks.
3. Measure the lateral runout. Refer to Brake Rotor Lateral Runout Check .
4. Measure the thickness variation. Refer to Brake Rotor Thickness Variation Check .
5. Mount the J 39144 on the spindle arbor. Use a suitable combination of spacers or collets in order to tighten the J 39144 to the arbor. Whenever you use lathes with a 7/8 inch spindle arbor, use an adapter sleeve with the J 39144 . Do not use an adapter sleeve with lathes using a 1 inch spindle arbor.
6. Mount the rotor onto the J 39144 .

Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

7. Mount the clamp plate and five nuts. You may install and remove the rotor while J 39144 is mounted on the machine spindle.

Tighten
Tighten the nuts in a cross pattern to 34 N·m (25 lb. ft.).

8. Install a silencer band on to the rotor.
9. Use the following procedure in order to verify correct installation of the rotor:

9.1.	Bring the tool bit up and touch off when the machine is running.

9.2.	Stop the machine and check the witness mark.

If the mark extends three quarters of the way around, the rotor is mounted properly.

10. If the rotor is mounted properly, continue with normal methods in order to resurface the rotor.
11. If the witness mark does not extend three quarters of the way around, repeat Steps 1 through 9.
12. Refinish the brake rotor. Refer to the brake lathe manufacturer's operating instructions.

Important: Failure to obtain the best possible braking surface finish may cause the vehicle to stop with difficulty.

13. After machining the rotor, use 120 grit aluminum oxide sandpaper and a non-directional rotor finisher (if available) in order to create a non-directional braking surface.
14. Clean the braking surfaces with denatured alcohol or with a suitable brake cleaner.