Brakes - Noise/Pedal Effort/Short Pad Life
NUMBER: 93-T-52CORP.REF.NO: 335003
DATE: April 1993
SECTION: 5
SUBJECT:
BRAKE PAD LIFE, BRAKE NOISE, OR BRAKE PEDAL EFFORT - REPLACE PADS/INSPECT ROTOR THICKNESS
MODEL/YEARS:
1988-93 CUTLASS SUPREME
This bulletin cancels and supersedes Dealer Technical Bulletin 91-T-217 and should be discarded.
CONDITION:
Some owners of 1988-93 Cutlass Supreme models may express concern with:
1. Brake Noise
2. Brake Pad Life
3. Brake Pedal Feel/Effort
CAUSE:
These vehicles are equipped with 4-wheel disc brakes. Some light brake squeal is NORMAL. 4-wheel disc brakes also typically have a firmer pedal feel. A cause for pedal effort or lining life concerns could be improper rotor finish. If the vehicle has had brake service which included rotor machining, that may be the cause.
CORRECTION:
A. Pads - Increased pad life AND lower pedal effort may be obtained by replacing both the front and rear original pads with the new 1993 pads.
Front Lining P/N 12510029
Rear Lining P/N 12510030
Note:
SOME BRAKE SQUEAL IS NORMAL
While the 1993 pads may result in an increase in pad life, and lower pedal effort and better feel, they may also be associated with higher levels of brake squeal at the beginning of brake apply ("Tip-IN" squeal), or at the end of brake apply ("Pinch - Out" squeal).
For servicing a vehicle where pedal feel/effort, rather than pad life is the primary concern, GMSPO will still carry the linings listed below. These linings are more aggressive and will reduce pedal effort even more. But, owners should be told that some "GRINDING/GROWLING" type noise is to be expected from these and IS NORMAL. DO NOT USE AS A GENERAL REPLACEMENT PART.
Front Lining P/N 18019507
Rear Lining P/N 18019508
RECOMMENDED SERVICE - BRAKE SQUEAL
DO NOT MACHINE ROTORS OR SAND PADS FOR BRAKE NOISE CONCERNS.
While this may temporarily reduce some brake squeal, it may also reduce brake effectiveness and/or pad life.
BRAKE SQUEAL is caused by vibration of brake components. Some intermittent brake squeal is NORMAL. Usually 3-4 aggressive stops will temporarily reduce or eliminate most brake squeal. If this does not work, remove, index (rotate wheel one (1) wheel bolt), and remount the wheels and make sure the wheel nuts are torqued in the STAR PATTERN to specification.
If the noise persists, a brake dampening compound may be applied to the back of each pad. Use Permatex Disc Brake Quiet # 126hb or equivalent.
B. Front Rotors DO NOT MACHINE ROTORS FOR THE FOLLOWING:
Pad Replacement
Brake Noise
Pedal Effort/Feel
Rotors should only be machined for:
Pulsation Concerns Heavy Scoring - In Excess of .060" (1.5 mm)
If the front rotors on a high-pedal-effort vehicle have been previously machined, they should be replaced. It is not always apparent with visual inspection whether a rotor has been turned. Rotor thickness should be measured with a micrometer. The thickness of a new rotor is 1.040" (26.4 mm). If a rotor measures 1.025" (26.0 mm) or less, on a vehicle with comments of pedal efforts, the rotor probably has been machined and should be replaced.
C. Rear Brakes
Also, the rear calipers should be inspected for caliper slide force. When the caliper is removed for pad replacement, try to move each sleeve with both thumbs pushing on the end of the sleeve. If one sleeve is found that won't slide, refer to Dealer Technical Bulletin 93-T-48 for the procedure to service the rear caliper sleeves. If one caliper has a sticking sleeve, both calipers should be serviced with this procedure.
PART AVAILABILITY:
Parts are currently available from GMSPO.
WARRANTY INFORMATION:
Use appropriate labor operations and times for each repair.