GM 15942198
Rotor, Front

To replace the front Brake Disc of the 25/3500 series you need j 41013 rotor resurfacing kit (J 41013) and j 42450-a wheel hub resurfacing kit (J 42450-A) tools. Clear the friction surface of the new disc by soaking it with brake cleaner or denatured alcohol. Disassemble the tire wheel and hub unit and remove the front wheel extension housing when present. Drive a large screwdriver into the disc to block rotation as you measure how the hub extension fits with the hub. Strike the hub extension gently with a rubber mallet to take it off its position after unhitching its mounting nuts. Look at the brake master cylinder reservoir fluid and drain extra fluid as needed. Apply two large c-clamps to stop brake caliper pistons and position the disc over the hub. Unite caliper and caliper bracket as one part and remove them together without disconnecting the brake hose. Remove associated Brake Disc locking nuts first then hit the disc-mate hub with a soft mallet if required. To remove a corroded disc fully use penetrating oil and force it off with two bolts t10 x 1.5. Apply j 42450-a and j 41013 kits to remove all rust and residue from hub flange and disc connection areas. You must put the hub flange through a quality inspection to remove any nicks and marks before fixing the disc position. Test the assembled disc side-to-side movement and resolve it when measurements exceed standard values. Clean and put threadlocker gm p/n 12345493 (Canadian P/N 10953488) on the caliper bracket bolts before fixing it back on the vehicle and tightening the bolts to 300 nm (221 ft. Lbs.). Carefully put back the front wheel hub extension of dual wheel vehicles while placing it in its normal position and tighten the nuts to 130 nm (96 ft. Lbs.). Put back the tire and wheel unit before slowly pressing the brake pedal to adjust the caliper piston position and check the master cylinder reservoir fluid level.

The service and repair of brake discs requires the usage of J41013 Rotor Resurfacing Kit (J41013) and J42450-A Wheel Hub Resurfacing Kit (J42450-A). The brake system requires no disc brake disc refinishing during regular maintenance while new discs should be free of this practice. Refinishing operations must be rare since they only benefit discs which maintain sound thickness with additional conditions beyond permissible specifications. Clean the hub/axle flange along with the brake disc mating surfaces from any dust and rust by adopting the J42450-A method then proceed with the J41013 on the disc itself. The brake disc should be mounted to the brake lathe while maintaining cleanliness on all attachments. Bring the cutting tools to meet disc friction surfaces during lathe operation while checking the witness mark to verify correct mounting. The manufacturer guidelines for the lathe should be followed to restore the disc shape while checking the material reduction after every cutting iteration. Brake discs need replacement when refinishing results in a disc that surpasses the specified minimum thickness. For a non-directional finish select the recommended grit sandpaper available for the lathe equipment then remove dust from friction surfaces by using denatured alcohol or an approved brake cleaner. The LRO measurement of the assembled brake disc must be completed for performance verification. Necessary adjustments should be made if the measurement surpasses established specifications.

Remove the brake caliper bracket mounting bolts and support the brake caliper with heavy mechanic's wire to prevent damage to the hydraulic flexible brake hose.

Ensure the mating surfaces are free of debris, align the rotor to its original position, and install it.

Clean all rust and contaminants from the hub flange and the inside diameter of the brake rotor.

Without disconnecting the hydraulic brake hose, remove the brake caliper bracket bolts and take off the brake caliper and bracket as an assembly, supporting it with heavy mechanics wire.

Use the Wheel Hub Resurfacing Kit (J42450-A) for the hub flange and the Rotor Resurfacing Kit (J41013) for the inside diameter of the brake rotor.

Strike the hub or rotor with a deadblow hammer, or use the Rotor Removal Tool (J-46277) with the Slide Hammer With Adapter (J 2619-01).

Remove the Conical Brake Rotor Washers (J 45101-100) and the lug nuts that were installed during the LRO measurement.

Clean any rust or contaminants from the hub/axle flange and brake rotor mating surfaces using the Wheel Hub Resurfacing Kit (J 42450-A) and the Rotor Resurfacing Kit (J 41013).

Adhere to the recommended speed settings and apply the finish using either a non-directional finishing tool with 120 grit aluminum oxide sandpaper or a sanding block with 150 grit aluminum oxide sandpaper.

Using two large C-clamps.

Clean them with the Wheel Hub Resurfacing Kit (J 42450-A) and the Rotor Resurfacing Kit (J 41013).

Remove the protective coating from any new rotor using denatured alcohol or an equivalent brake cleaner, as oil-based solvents can damage the brake lining and pose a fire hazard.

Ensure no debris remains on the mating surfaces.

Wait 15 seconds and repeat this process until a firm pedal is obtained to properly seat the brake caliper pistons and brake pads.

To achieve a firm pedal, which will properly seat the brake caliper pistons and brake pads.