DISC BRAKE PULSATION 1976-82 'T' CARS

VEHICLES AFFECTED: 1976-82 'T' Cars ----------------

Information in this Service Bulletin supercedes information contained in Chevrolet Service Bulletin No. 1981-50-104.

Front disc brake pulsation may be caused by friction variation, rotor thickness variation, and high caliper sliding force causing uneven wear.

Vehicles experiencing front disc brake pulsation resulting from high caliper sliding force should be serviced with a new stainless steel caliper slide pin mounting bolt and sleeve service kit, P/N 18012093.

The kit includes one (1) stainless steel caliper slide pin mounting bolt, one (1) stainless steel sleeve and a one-quarter (1/4) ounce packet of silicone grease. One (1) kit services one (1) caliper. The new kits will not service 1983 and later vehicles.

When servicing the front disc brake rotor for repair of front brake pulsation of the 1976 through 1982 'T' cars, additional attention must be given to the reaction surfaces of the caliper mounting bracket to avoid a possible recurrence of pulsation which may be due to binding calipers which may result in uneven rotor wear. In addition to shop manual procedures for rotor replacement or resurfacing the following steps should be performed:

1. Measure the distance between the brake reaction surfaces of the caliper mounting bracket (reference surfaces 'A' and 'B' on the attached illustration). This distance must be 92.5 mm. If this distance is less than 92.5 mm, remove some material by filing at surface 'B' only. Do not exceed 92.5 mm when performing this function.

2. Remove all corrosion from mating surfaces of the caliper and caliper bracket.

3. Using crocus cloth, remove all corrosion from the caliper housing slide pin mounting bolt sleeve hole.

4. Install new cushions from clip and cushion kit, P/N 18009444.

5. Using the packet of silicone grease included in kit, P/N 18012093, lubricate the new slide pin mounting bolt, sleeve, clip, and surfaces 'A' and 'B' of the caliper bracket.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.