GM 19202731
Rotor, Front

The brake disc needs routine service work only when visible damage like excessive rusting, surface cracks, or deep scores appears. Evaluate disc thickness and surface level to determine if resurfacing maintains its usable life. Rub off wheel bearing flange rust using the Disc Resurfacing Kit (J 41013) while the Wheel Hub Resurfacing Kit (J42450-A) removes rust from brake disc contact surfaces and mounting areas. Follow brake lathe manufacturer directions to mount the brake disc while cleaning all attachments. After starting the lathe you need to let cutting tools meet the disc surface and check for the witness mark while rotating; if it does not reach three-quarters of the disc circumference you have to reposition the disc for further processing. Refinish the disc as per lathe manufacturer directions while checking the thickness after each cut and replacing the part when the minimum thickness is crossed. Use 120 grit aluminum oxide sandpaper at recommended speed to sand friction surfaces non-directionally when using a tool with this option. For sanding blocks without this option use 150 grit aluminum oxide instead. Wipe the touching disc surfaces with brake cleaner or denatured alcohol prior to detaching from the lathe.

These are the tools needed to service and repair brake discs: In order to service the brake disc two tools are needed: Rotor Resurfacing Kit (J 41013) and Wheel Hub Resurfacing Kit (J 42450-A). Rotor Resurfacing Kit (J 41013) and Wheel Hub Resurfacing Kit (J 42450-A). Brake disc refinishing should only occur as part of routine service when any combination of excessive corrosion, cracks, excessive bluing, scoring beyond maximum specifications, lateral runout, or thickness variation occurs. Measurement of disc surface wear and thickness should take place on each brake disc. Refinish the wheel bearing flange using Rotor Resurfacing Kit (J 41013) and resurface the brake disc mating surface and mounting face using Wheel Hub Resurfacing Kit (J 42450-A). Mount the brake disc to the lathe while following the manufacturer's directions and verify that all connections remain clean. Use the lathe to advance cutting tools toward the disc mate surfaces while observing the witness mark to confirm tool position. Re-mount when required following the lathe manufacturer's instructions to execute disc refinishing procedures with repeated thickness checks. Brake discs with thickness above the minimum tolerance require replacement after refinishing. When executing non-directional finishing operations utilize the recommended speed of the lathe together with 120 grit aluminum oxide sandpaper when equipped with a directional tool or 150 grit aluminum oxide sandpaper alongside a sanding block as an alternative. All friction surfaces require cleaning with denatured alcohol or brake cleaner equivalent until you remove the disc from the lathe.

You must first lift the vehicle and position support stands under it before taking off the tire and wheel set. Position a c-clamp model j 41013 between brake caliper and piston to compress the parts together until the caliper moves away from the Brake Disc. Afterward remove the clamp. Secure the brake caliper safely using mechanics wire to shield the hydraulic hose from harm. To ease assembly removal place the brake caliper assembly with caliper mounting bracket directly off the suspension knuckle before any hydraulic brake hose tension builds up. Keep the markings you made earlier while you take off the Brake Disc. Before assembly cleanse the hub/axle flange and Brake Disc contact surfaces by using wheel hub resurfacing kit component j 42450-a and rotor resurfacing kit j 41013. Use the mark from before removal to put the Brake Disc directly onto the hub/axle flange when both surfaces appear clean. To make sure your brakes perform well check the Brake Disc runout when adding it back into the brake system. Adjust the disc if its measurement fails to match the proper specifications. After placing the brake bracket and caliper set in place put back the wheel unit and then lower the vehicle. Normally pad and disc burnishing will be required.

Reinstall the tire and wheel assembly.

Bring in the cutting tools until they contact the rotor friction surfaces and check the witness mark to confirm proper mounting.

Mount it to the brake lathe according to the manufacturer's instructions, ensuring all attachments are clean.

Bring in the cutting tools to contact the rotor friction surfaces and check the witness mark to confirm proper mounting.

Corrective action is required.

Accurate control of rotor tolerance is essential for optimal disc brake performance.

Clean any rust or contaminants from the wheel bearing flange and the brake rotor mating surfaces.

Sufficient cooling periods should be allowed between stops to effectively burnish the brake pads and rotors.

Use the Wheel Hub Resurfacing Kit (J 42450-A).

Follow the lathe manufacturer's instructions to refinish the rotor, inspecting thickness after each cut.

Cleaning prevents increased lateral runout and brake pulsation.

Detach the rear brake caliper and mounting bracket, supporting them with a locally fabricated hook.

Install the brake rotor to the hub/axle flange using the matchmark made prior to removal for proper orientation.

Matchmark the brake rotor's position to the wheel studs.

Remove the brake caliper and bracket from the vehicle, ensuring the caliper assembly is supported away from the rotor.

Failing to support the brake caliper may damage the brake hose and lead to a brake fluid leak.

Support the brake caliper with heavy mechanic's wire or an equivalent whenever it is separated from its mount while the hydraulic flexible brake hose remains connected.

Clean any rust or contaminants from the wheel bearing flange and the brake rotor mating surfaces using the appropriate resurfacing kits.

Use the Wheel Hub Resurfacing Kit (J 42450-A).

Remove the C-clamp and support the brake caliper with heavy mechanic's wire or an equivalent.

Reinstall the tire and wheel assembly.

Clean the mating surfaces on the rotor and the wheel bearing flange, then install the caliper bracket.

First, remove the tire and wheel assembly.

Clean with J 42450-A.

Use the Wheel Hub Resurfacing Kit (J 42450-A) to clean the mating surfaces.

Reinstall the tire and wheel assembly.

Mark the relationship of the rotor to the hub.

Lower the vehicle and burnish the pads and rotors.

First, raise and suitably support the vehicle, then remove the tire and wheel.

The rotor should be re-mounted.

Measure the assembled lateral runout (LRO) to ensure optimal performance.

The rotor must be replaced.

Remove the caliper bracket.

Remove and support the caliper and bracket as an assembly without disconnecting the hydraulic flexible brake hose.

J 41013 Rotor/Drum Flange Resurfacing Kit (J 41013) and J 42450-A Hub Cleaning Kit (J 42450-A).

The indexing method is effective for small LRO exceedances of 0.025-0.127 mm (0.001-0.005 in) and aims to match high spots to low spots between related components.

Repeat the indexing and measurement process until the best assembled LRO measurement is achieved, and matchmark the final rotor location to the wheel studs if the orientation differs from the original.

Put the tire and the wheel back on.

Use the Wheel Hub Resurfacing Kit (J 42450-A) for the hub/axle flange and the Rotor Resurfacing Kit (J41013) for the brake rotor.

Clean the surfaces properly before installing the new rotor.