Pontiac 18060242 Front Brake Rotor Assembly

Raise the car, support it with jack stands, and remove the wheel and tire assembly. Remove the brake caliper, and support with wire. Remove the dust cap and remove the cotter pin and the bearing retaining nut. Remove the outer wheel bearing and place it in a clean location. Remove the wheel bearing, hub, and disc assembly from the spindle. Installation is in the reverse order of removal. Check the disc for any obvious defects such as excessive rust, chipping, or deep scoring. Make sure there is no wheel bearing play by performing the wheel bearing adjustment procedure. Then, check the disc for run-out by installing a dial indicator on the caliper so that its feeler will contact the disc about one inch below its outer edge. Turn the disc and observe the run-out reading. If the reading exceeds 0.002 in. (0.05mm), replace the disc. Check the caliper thickness with a vernier caliper or other appropriate tool. Minimum thickness dimensions are cast into the disc. Adjust the wheel bearings.

Whenever the disc brake pads are inspected for wear, it is important to also check the condition of the disc (rotor) surfaces. Light scoring or grooving is normal, but deep grooves or severe erosion are not acceptable. Models from 1974 and earlier feature a single deep groove known as a 'squeal' groove, which should not be mistaken for damage. If vibration occurs during brake pedal application, disc runout may be the cause. To check for this, a dial gauge or feeler blades can be used between the disc and a fixed point, ensuring that the runout does not exceed 0.004 inches. Variations in disc thickness greater than 0.0005 inches can also lead to vibration during braking. Discs typically have wear limit and refinish thickness dimensions cast into them, and if a dealer cannot refinish a disc to meet specified tolerances, a new disc must be installed. When a brake drum is removed for lining inspection, it should be checked for cracks, scoring, or being out of round. An out-of-round drum can cause a pulsating feeling in the brake pedal during application, and the internal diameter should be measured at various points using an internal micrometer. Drums can be refinished internally as long as the wear and refinish sizes cast into them are not exceeded.

To inspect the brakes, begin by loosening wheel lug nuts and raising the front of the vehicle on jack stands. Take off the wheel followed by the brake caliper. While checking for any score marks or damage on disc surfaces, remember that slight scratches and shallow grooves are normal and will not affect the brake operation. Nevertheless, deep grooves of over 0.015-inch deep necessitate disc removal and refinishing at a machine shop. Make sure both sides have been inspected thoroughly. When inspecting a rear disc, reinstall wheel lug nuts with flat side towards disc to hold it in a flat vertical plane during inspection. Washers may be needed under lug nuts to apply pressure to disc. To check for disc runout, place dial indicator about 1/2 inch from outer edge of disc and zero it out. Turn disk around while making sure that reading does not exceed 0.003 inches on indicator gauge; if it does so, then let machine shop refinish disk for you.Additionally don't allow multiple groves on your brake rotors which should be well maintained as long as they don't wear below specified minimum thickness.It is also possible to measure rotor thickness with micrometer.For removal and installation, on 2WD models, the disk is part of the front hub assembly and should be removed and installed according to front wheel bearing maintenance procedure.On 4WD models remove tire; remove caliper , then pull off disk from its mounting onto hub.

Raise the vehicle and place it securely on jackstands, then remove the appropriate wheel and tire. Next, remove the brake caliper assembly, ensuring not to disconnect the brake hose on front disc brakes; after removing the caliper mounting bolts, hang the caliper out of the way using a piece of wire, avoiding any strain on the brake hose to prevent damage. Inspect the Brake Disc surfaces for light scoring or grooving, which is normal, but be cautious of deep grooves or severe erosion, especially if pulsating has been noticed during brake application, as this may indicate disc run out. Attach a dial indicator to the caliper mounting bracket, turn the Brake Disc, and note the amount of run out, checking both inboard and outboard surfaces; if the run out exceeds the maximum allowable, the Brake Disc must be removed and taken to an automotive machine shop for resurfacing. Measure the thickness of the Brake Disc with a micrometer, and if it is less than the minimum specified, replace it with a new one, also measuring the disc thickness at several points to check for variations; any variation over 0.0005-inch may cause pedal pulsations during brake application, and if this condition exists while the disc thickness is above the minimum, the Brake Disc can be removed for resurfacing. For the removal and installation of the front Brake Disc, check and repack the wheel bearings, and note that the Brake Disc on rear wheel disc brake models can be pulled off after the caliper is removed.

Check for any score marks or damage. Keep in mind that light scratches and shallow grooves are normal and won't affect brake operation. However, deep grooves over 0.015-inch deep will require disc removal and refinishing by a machine shop.

It is important to also check the condition of the disc (rotor) surfaces.

Start by loosening the wheel lug nuts and raising the front of the vehicle on jack stands. Remove the wheel and then the brake caliper.

Reinstall the wheel lug nuts with the flat side towards the disc to hold it in a flat, vertical plane during the inspection. You may need to use washers under the lug nuts to apply pressure to the disc.