GM 19303831
Brake Rotor, Front

These brake disc services need the Rotor Resurfacing Kit (J41013) and Wheel Hub Resurfacing Kit (J42450-A). Routine brake maintenance should not include refinishing disc brake discs since this is not necessary for their upkeep. New discs must remain unrefinished too. The disc needs adequate thickness and shows issues like uneven thickness, rust damage, open cracks, heating spots, abnormal discoloration, or too deep scores to justify resurfacing. To prepare both parts for finishing use J42450-A Wheel Hub Resurfacing Kit and J41013 Rotor Resurfacing Kit to clean rust and surface contaminants from hub/axle and brake disc components. Secure the brake disc on the brake lathe when both surfaces are ready for work. Clean all hardware connections before starting. As you run the lathe tools approach the disc friction areas to check if they properly contact the surface. Use lathe manufacturer guidelines to shape the disc then check its thickness at each cutting step. When a disc reaches its minimum allowed thickness during refinishing procedures it needs to be replaced. To achieve a random surface texture use 120 grit aluminum oxide sandpaper on the non-directional finish tool if it comes with one but switch to 150 aluminum oxide sandpaper when using a regular sanding block. Use denatured alcohol or brake cleaner to clean the brake surfaces then check the LRO results to see if the brake system needs adjustment when the measurements go beyond allowed values.

Begin the repair of the Brake Disc. Look at every disc Brake Disc to see if the surface is worn out, if there is lateral runout, and make sure it is still above the minimum allowed size after resurfacing. When refinishing because the parts are corroded, cracked, or scored beyond standards, fit the Brake Disc to the brake lathe as the manufacturer says, and check that everything is clean. Let the lathe run while you move the cutting tools toward the disc friction surfaces and look at the witness mark to make sure they are mounted properly. Use the manufacturer's guide to refinish the disc, keep checking the thickness after every cut, and fit a new disc if it gets too thin. You can get a non-directional finish by using the recommended speed and 120 grit aluminum oxide sandpaper if you have a non-directional tool, or with 150 grit sandpaper and a sanding block if you don't. Once you are done, wipe each friction surface with denatured alcohol or brake cleaner, then take the disc off the lathe.

Brake rotor thickness variation should be measured.

Clean any rust or contaminants from the wheel bearing flange and the brake rotor mating surfaces with the Wheel Hub Resurfacing Kit (J42450-A).

Inspect the thickness after each cut, and if the rotor exceeds minimum allowable thickness, it must be replaced.

Inspect the mating surfaces to ensure no foreign particles remain.

Follow the recommended speed settings and apply the finish using 120 grit aluminum oxide sandpaper with a non-directional finishing tool, or 150 grit aluminum oxide sandpaper with a sanding block if not equipped.

Begin by selecting a smooth road with minimal traffic.

Remove the tire and the wheel.

Detach the brake caliper from the mounting bracket without disconnecting the hydraulic brake flexible hose, then remove the brake caliper bracket assembly.

Support the brake caliper with heavy mechanic's wire or an equivalent to prevent damage to the hydraulic flexible brake hose.

Clean each friction surface of the brake rotor with denatured alcohol or an equivalent approved brake cleaner.

Re-mount the rotor if necessary.

Using gasoline, kerosene, or other oil-based solvents that may leave a damaging residue.

Support the brake caliper with heavy mechanic's wire to prevent damage to the hydraulic flexible brake hose while it remains connected.

Clean each friction surface with denatured alcohol or an equivalent brake cleaner before removing the brake rotor from the lathe.

Remove the brake rotor.

Put the tire and the wheel back on and lower the vehicle.

Raise and suitably support the vehicle, then remove the tire and wheel.

Begin by checking the brake rotor thickness variation with Conical Brake Rotor Washers (J 45101-100) before assessing the assembled lateral runout (LRO).

Clean the wheel bearing and hub with the Hub Cleaning Kit (J 42450-A), then measure the thinnest point of the brake rotor with a micrometer.

Each friction surface should be cleaned with denatured alcohol or an equivalent brake cleaner.

Inspect both surfaces for foreign particles or debris.

Refinishing is necessary if there is thickness variation exceeding the maximum allowable specification, excessive corrosion or pitting, cracks or heat spots, excessive blueing discoloration, or scoring beyond the maximum allowable specification.

A strap or heavy gauge wire.

Install the tire and wheel assembly, lower the vehicle, and if the brake rotor was refinished or replaced, burnish the pads and rotors.

Use a C-clamp to compress the brake caliper piston enough to allow the caliper to slide away from the rotor, and then remove the C-clamp.