Brake Rotor Refinishing Front

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 instructions for all initial setup and cutting procedures.

The Accu Turn® Brake lathe is GM dealer equipment. Refer to the manufacturer instructions for all initial setup and cutting procedures.

It is very important that the rotor surface be made nondirectional by dressing the rotor surfaces with a sanding disc tool such as Ammco® 8750 Safe Swirl Disc Rotor Grinder, Accu Turn® 433179 Non-Directional Swirl Finisher, or equivalent, using 120 grit aluminum oxide sandpaper. 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, an alternate method is to use a sanding block with 150 grit aluminum oxide sandpaper. 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. 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 to that of a new rotor as possible. Failure to obtain the best possible rotor finish may affect braking performance.

Brake Rotor Refinishing Rear

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 instructions for all initial setup and cutting procedures.

The Accu Turn® Brake lathe is GM dealer equipment. Refer to the manufacturer instructions for all initial setup and cutting procedures.

It is very important that the rotor surface be made nondirectional by dressing the rotor surfaces with a sanding disc tool such as Ammco® 8750 Safe Swirl Disc Rotor Grinder, Accu Turn® 433179 Non-Directional Swirl Finisher, or equivalent, using 120 grit aluminum oxide sandpaper. 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, an alternate method is to use a sanding block with 150 grit aluminum oxide sandpaper. 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. 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 to that of a new rotor as possible. 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. Ensure that all components are clean and in good condition. Inspect all the mounting hardware for the following conditions:

•

Rust

•

Nicks

•

Dirt

•	Abnormal wear

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 (1). Use a suitable combination of spacers or collets (5) in order to tighten the J 39144 to the arbor. Whenever you use lathes with a 7/8 inch spindle arbor, use a J 37160-50 with the J 39144 . Do not use a J 37160-50 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 can install and remove the rotor while the 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 the silencer band onto the rotor.
9. Set the spindle speed to approximately 150 RPM (or mid-range).
10. While the machine is running, bring the tool bit up and touch off. Stop the machine and check the witness mark. If the witness mark goes ¾ of the way around, the rotor is mounted properly. Continue with normal methods to resurface the rotor.
11. If the witness mark does not go ¾ of the way around, repeat the previous steps.