GM 19174917 Front Brake Rotor Assembly

Before replacing the brake components, the vehicle has to be lifted and properly supported it is then necessary to also remove the wheel and tire assembly. Subsequently, unbolt the brake caliper from the axle and then using a wire fix the brake caliper on the coil spring but not to the brake hose. On the 1990-91 Eldorado and Seville models, the caliper mounting bracket must be unbolted from its position to be removed. If present, then simply remove the retainers from the wheel studs since the retainers do not come back on. Completely disassemble the disc brake rotor and analyze the situation, then turn to machining or replacement of it. For the installation, position of the disc brake rotor over the wheel studs and hub assembly, further for the 1990-91 Eldorado and Seville models use the new bolts to attach the caliper mounting bracket and tighten to 83 ft lbs. (112 Nm). Reinstall the brake caliper and after that the wheel and tire assembly, and then the vehicle should be lowered again. While inspecting, observe whether the rotor surface is shiny due to overheating, or glazed, or scored; machining of discoloration or glazed rotor is required, whereas light score up to 0.050 inch is allowed. (1.2mm) is typically acceptable. Check rotor thickness at at least four points in the circumference and any variation greater than o.0005 inch indicated by a dial indicator can cause brake pedal pulsation. (0.013mm) necessitates machining. Further, check for too much side play as this is probable to make the vehicle shake upon application of brakes. Run out in the lateral direction can be tested again by re fastening rotor with wheel lug nuts, placing dial indicator on the steering knuckle or caliper mounting bracket then making total indicated run out when the rotor has revolved once fully. In the case of large runout the shaft could be indexed on the rotor on the hub to correct the condition. Otherwise check the hub and bearing assembly for excessive lateral runout or looseness and replace it and again check the rotor. If the rotor still stays over the specifications, then machine it but it must not go below the minimum standards.

In order to carry out operations for replacement of brake components, it is necessary to lift and securely fix the car, and then to unscrew the wheel and the tire. Afterward, unbolt the brake caliper, and using a wire, hang the brake caliper from the strut paying attention not to suspend it by the brake hose. For 1992-98 vehicles first, remove the disc brake pads from the caliper mounting bracket, then proceed to remove the caliper mounting bracket mounting bolts and lastly the bracket. However, if available, it will be useful to remove the retainers from the wheel studs since they are not to be reused. Extract the disc brake rotor and examine it, and if possible machine or replace the same. For installation, slide the disc brake rotor over the wheel studs and hub and secure it with the caliper mounting bracket that uses new mounting bolts which should be tightened to 83 ft. lbs. (112 Nm). For the vehicles of the years up to 1998, firstly, the disc brake pads should be fitted in the caliper mounting bracket then the brake caliper. Last of all, fit back the wheel and tire assembly and then lower the car.

Before you start, lift the car safely and take out the tire and wheel together. After taking off the brake caliper, hold it above the ground using a wire through the coil spring. Keep the brake hose away from the weight. When you have them, take off the wheel studs' retainers and throw them away because you won't use them again. After you take out the disc brake rotor, examine it, and either fix with fine work or buy new parts. Press the rotor onto the truck's wheel studs and hub handle before hanging the brake caliper in place. After that, put the wheel and tire together and let the vehicle go back down to the ground. Check the rotor surface condition for any brown discolorations from overheating or shiny and thin (glazed) areas, along with gouges; if spotted, you must repair it through machine work. Scoring under 0.050 inches (1.2 millimeters) is usually allowed, but heavy scores need refinish work that matches strict minimum thickness rules. Check how evenly the rotor is built up. Too much difference in thickness can cause the brake pedal to shake or bounce when pressed. Measure the rotor's thickness at different spots around its edge, and make sure you test the same point about 1 inch from the rim each time. A rotor needs to be ground when it varies by more than 0.0005 in. (0.013mm) while following minimum thickness requirements must be followed. Look for uneven tire-to-wheel alignment that causes shaking when you brake, though you may not feel it through your foot. To find out if your wheel runs true, disconnect the tire, screw the wheel nuts back on, attach a dial gauge to the steering knuckle or caliper frame, and make sure its indicator tip touches the rotor's surface half to one inch away from the edge. Reset the indicator, let the rotor spin fully, and record any measurement on the dial. You can fix any extra movement by moving the hub along its wheel stud an extra turn or two. When indexing is not sufficient, check the hub and bearing assembly for side-to-side vibration or looseness. Replace the entire unit and check the rotor again if either exceeds 0.0015" in (0.040mm) on Deville and Fleetwood models. When lateral runout won't decrease enough, machine the rotor based on specific minimum thickness rules.

Next, detach the brake caliper and suspend it with wire from the strut, ensuring it does not hang from the brake hose.