GMC 1976 ZEO 6083 Maintenance Manual page 226

EXCESSIVE PEDAL PRESSURE
REQUIRED TO STOP VEHICLE
Cause
Brake adjustment not correct.
Improper lining .
Improper shoes.
Grease or fluid soaked linings.
Rusted wheel cylinder .
Wheel cylinder link incorrectly
aligned.
Compensating port not cleared .
Brake pedal binding on shaft.
Glazed linings.
Bellmouthed, barrel-shaped or
scored drums.
CRUNCH OR GROAN, HOLDING
VEHICLE ON HILL
Cause
Brake dust and possibly linings
which have been overheated .
HIGH PITCH SQUEAK WHILE
BRAKES OPERATE
Cause
New linings not yet fully
burnished .
Persistent squeak-no apparent
cause.
REAR BRAKES DRAG
Probable Cause
1 . Maladjustment.
2 .
Parking brake cables frozen .
Remedy
Adjust brakes .
Install factory specified shoes.
Install factory specified shoes.
Correct cause and replace linings, if necessary.
Replace.
Check wheel cylinder piston and boot for damage .
Install link .
Check pedal linkage, stop light switch adjustment .
Lubricate with Delco Brake Lube
#5450032
(or
equivalent) .
Sand surface of linings.
Replace or resurface drums in left and right hand
pairs.
Remedy
Sand linings and remove dust from brakes .
Remedy
BRAKES 5- 7
Burnish further or sand off high spots of linings .
Sand linings for temporary cure or mild cases.
Install drum springs for stubborn cases of high
pitch squeak .
Remedy
1 . Adjust brake shoes and parking brake mechanism .
2 .
Lubricate with Delco Brake Lube
#5450032
(or
equivalent).