For 1990-2009 cars

# CAMPAIGN: TO CORRECT BRAKE BACKING PLATE CORROSION

#### MODELS: 1978 to 1984 Chevrolet Malibu, Monte Carlo & El Camino, Pontiac LeMans & Grand Prix, Oldsmobile Cutlass, Buick Century and Regal and GMC Caballero 1982 to 1984 Chevrolet Camaro & Pontiac Firebird 1982-1984 Chevrolet & GMC S & T Light Trucks

TO ALL AFFECTED GM DEALERS

Letters are being mailed to owners relative to an upcoming campaign on the above vehicles (copy attached). A campaign bulletin with more detailed information will be mailed to your Dealership by FebrUdry 1, 1985 and owners have been advised to contact their Dealer on or after that date. Necessary service parts will also be available by that date. In the meantime, if any concerned customers contact your Dealership and insist on immediate action prior to your receipt of this information, the procedure shown below is to be used. In the event that a vehicle is brought to your Dealership with a rear brake system failure resulting from this condition, refer to procedure section 2B.

1. Hoist vehicle and inspect the inboard surface of both rear backing plates for evidence of rust-through (perforation).

A. If no rust-through (perforation) is evident, no further action is required prior to the campaign action.

2. If there is evidence of rust-through (perforation) of the backing plate, remove the wheel and brake drum and inspect the position and retention of the wheel cylinder as follows:

A. If at least 50% of the wheel cylinder piston diameter is in contact with both the primary and secondary brake shoes and there is no evidence of rust-through on the outboard side of the backing plate in the area of the wheel cylinder, no further action is required.

B. If the wheel cylinder platons are not properly contacting brake shoes as defined in 2A or if there is evidence of rust-through of the backing plate, replacement of backing plate and wheel cylinder using currently available service replacement parts will be necessary after Zone Office approval is obtained.

3. Arrange an appointinent with owner to have vehicle campaigned per instructions in forthcoming bulletin, regardless of action performed in Steps 1 and 2.

#### CLAIM INFORMATION:

If an inspection or remedial repair is required in connection with this owner mailing, claim through the warranty system using special labour operation: T800300 (1978-79 Vehicles) or T8003 (1980-84 Vehicles).

#### NOTE: All claims of this type require Zone approval.

Time allowances are as follows.

1. Inspection of inboard side of backing plates .3 Hrs.

2. Inspection of outboard side of backing plate .5 Hrs. (one side)

3. Inspection of outboard side of backing plates .7 Hrs. (both sides)

4. Replacement of backing plate and wheel cylinder 1.1 Hrs. (one side)

5. Replacement of backing plates and wheel cylinders 1.7 Hrs. (both sides)

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.