GM 15942195
Rotor, Front

Before starting you must lift your vehicle then take off its tire and wheel parts together. Make any necessary marks on the disc to its connection with the hub before using a c-clamp to compress the brake caliper pistons for removal. You must suspend the caliper on mechanic's wire to shield the hydraulic brake hose from damage. First take out the complete brake caliper assembly including its bracket. Then detach the disc holding push nuts depending on the vehicle design. When corrosion makes the disc difficult to detach use penetrating oil to clean both parts before inserting m10x1.5 bolts through the disc threaded holes and tightening them to separate the disc from the hub. Before fitting clean the hub flange with wheel hub resurfacing kit (J42450-A) and clean the inside Brake Disc diameter using rotor resurfacing kit (J41013). Surface cleaning comes first then position the disc back where it belongs. When fitting the disc to a brake system repair check lro assembly and fix if it is off standard. Fix the caliper and bracket together by cleaning all bolt threads first then applying threadlocker gm p/n 12345493 (Canadian P/N 10953488) before tightening bracket mounting bolts using the correct torque. After installing the wheel and tire set down the vehicle. Apply and release the brake pedal to position the caliper pistons correctly and fill the brake fluid reservoir with fresh brake fluid.

In order to fix the assembled lateral runout (LRO) of the Brake Disc, one must ensure that there is a thickness variation of the Brake Disc, by going beyond the maximum allowable level can cause brake pulsation. Start by removing the conical Brake Disc washers (J 45101-100) and lug nuts that were put in place when taking lro measurement. Check the mating surface of the hub- axle flange, and Brake Disc for foreign part oo leakcs. Next, orientate the Brake Disc in an alternated direction to the hub/axle flange and hold it firm in place and install one conical Brake Disc washer (J 45101-100) and one lug nut on the top most wheel-stud and torque the lug nut using hand torque only. Keep holding the disc steady as you mount the remaining conical Brake Disc washers (J 45101-100) and lug nuts onto the wheel studs until they are hand-tightened in a star-pattern. With the help of the torque-limiting socket set (J 39544-KIT), loosen the lug nuts then tighten them in a star-shape pattern to specifications so that the disc may be properly secured. Measure the braided lro of the Brake Disc and compare the measurement with the original. If it meets specifications, then proceed to install the brake caliper and push the brake pedal severally to hold the disc in position before removing the conical Brake Disc washers j 45101-100 as well as the lug nuts. If the measurement does not meet specifications, redo the indexing and tightening of the process until you have your best assembled lro measurement and matchmark the location of the disc to the wheel studs if your orientation is not the same as the original. In the event that the assembled lro exceeds the maximum specification, one may need to make further correction.

A check for Brake Disc thickness variation is needed at first step of disc service since excessive variation leads to brake pulsation problems. Clear all rotating parts such as brake discs from their contact with caliper and caliper bracket. During service and repair take off the conical Brake Disc washers (J 45101-100) and the lug nuts from the assembled lateral runout measurement operation. Check if any unwanted particles or dirt exist on the hub/axle flange mounting area and the Brake Disc surface. Follow the lathe setup instructions provided by the manufacturer and use it to refine the Brake Disc while checking thickness every time you make a cut. You must replace the Brake Disc since it remains thicker than set limits despite the refinishing process. After your work finish the surfaces with non-directional steel wool of 120 grit aluminum oxide or sand the surfaces with 150 grit aluminum oxide sandpaper, and then clean both friction areas with either denatured alcohol or brake cleaner. Check the Brake Disc's combined thickness measurement after taking out the lathe system. When the measurement fits within acceptable ranges put back the brake caliper and loosen the brake pedal several times to secure the disc before you take out the brake washer and lug nuts.

You must check brake disc thickness variation first because high measurements can cause brake vibration. When the assembled LRO reaches beyond its acceptable limits the brake disc shows thickness differences starting at 4,800 km and continuing until 11,300 km of driving distance. LRO adjustment requires two different methods which match to the vehicle type being repaired. The indexing method proves successful for small LRO overages from 0.025 mm to 0.127 mm (0.001 inch to 0.005 inch). It helps align matching high and low points on related pieces. When a brake disc exceeds limits the vehicle brake lathe tool helps restore proper specifications by modifying both the disc and LRO measurement. When these techniques fail to fix the problem further inspection is needed to identify other possible reasons behind the LRO concern.

Clean the bolt threads, apply Threadlocker GM P/N 12345493 (Canadian P/N 10953488), and tighten the caliper bracket mounting bolts to the specified torque.

Tighten to 175 Nm (129 ft. lbs.) for the 15 Series or 300 Nm (221 ft. lbs.) for the 25 Series.

Assemble the rotor removal tool (J-46277) to the slide hammer (J 2619-01) and insert it between the rotor friction surfaces to aid in removal.

Detach the brake rotor and hub assembly from the rear axle, marking the relationship of the hub to the rotor.

Remove them as an assembly without disconnecting the hose.

Pull down on the intermediate cable and then release it from the equalizer bar.

Remove the tire and wheel assembly.

Index the brake rotor in a different orientation to the hub/axle flange, hold it firmly in place, and install one Conical Brake Rotor Washer (J 45101-100) and one lug nut onto the upper-most wheel stud, tightening the lug nut securely by hand.

To avoid poor braking performance.

Inspect the mating surfaces for foreign particles, then mount the brake rotor to the brake lathe, ensuring all attachments are clean.

Clean the bolt threads and apply Threadlocker GM P/N 12345493 (Canadian P/N 10953488) before tightening the caliper bracket bolts to 200 Nm (148 ft. lbs.).

Excessive corrosion, cracks, or scoring beyond the maximum allowable specification.

Reinstall the tire and wheel assembly, lower the vehicle, and properly seat the brake caliper pistons and pads by applying and releasing the brake pedal multiple times before filling the master cylinder reservoir with clean brake fluid.

Reattach the quarter shaft shield and tighten its nut and bolt to 25 N.m (18 lb ft).

Inspect the brake master cylinder reservoir fluid level; if it exceeds the midway point, remove fluid until it reaches that level.

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

Remove the lug nut and washers.

Fill the master cylinder reservoir to the proper level with clean brake fluid.

Remove the tire and wheel assembly, mark the rotor's relationship to the hub, and compress the brake caliper pistons using two large C-clamps.

Inspect the thickness after each cut.

Reduce it to the midway point.

Mount the brake rotor to the brake lathe, ensuring all attachments are clean.

Clean any rust or contaminants from the hub/axle flange and brake rotor mating surfaces.

Remove the rotor, axle shaft, park brake shoe, and backing plate bolts.

Clean the bolt threads and apply Threadlocker GM P/N 12345493 before tightening the caliper bracket bolts to 200 Nm (148 ft. lbs.).