Pontiac FIREBIRD 1972 Service Manual page 406

BRAKES
-
GENERAL
5-3
Pedal does not return freely.
Compensating port of master cylinder closed.
BRAKES DO NOT AUTOMATICALLY ADJUST
CAUSE
Worn, bent or distorted adjuster lever.
Improper secondary lining to drum clearance.
Brake linings excessively worn.
SPONGY PEDAL
CAUSE
Air trapped in hydraulic system.
Brake adjustment not correct.
Bent shoes.
Compensating port closed.
CAR PULLS TO ONE SIDE
CAUSE
Grease or fluid on lining.
Improper lining contact with drum.
sufficiently to obstruct the compensating port. Flush
system thoroughly with a good grade of clean brake
fluid and replace all internal rubber parts in
brake system.
Lubricate pedal linkage and make certain no bind
exists. See that stop light switch is not defective,
incorrectly adjusted, or that switch plunger is not
binding on pedal due to lack of lubrication.
The compensating port in master cylinder must be
completely clear when pedal is in released position.
1. See that pedal returns freely and is not stopped
by contact with stop light switch body or pedal
bracket.
2. See that compensating ports are not plugged by
dirt. To check compensating port, remove master
cylinder reservoir cover and watch the fluid in the
cylinder as the brake pedal is moved. A geyser
should be seen as the pedal is first depressed. If no
geyser is seen, the compensating port is blocked.
3. Inspect master cylinder primary piston cup and
if found to be swollen or elongated, flush system and
replace damaged parts.
REMEDY
Replace adjuster lever.
Adjust clearance.
Install new linings.
REMEDY
Remove air by bleeding (check compensating port for
clearance of cup to provide full open port).
Adjust brakes.
Replace.
See all brakes drag.
,
REMEDY
Replace with new linings. Except on new cars it
is almost always necessary to replace linings of
both front brakes if one is damaged. See BRAKE
CAUTIONS. Linings with even a slight trace of grease
or fluid may effect the operation of the brakes
and can seldom be salvaged by cleaning. Correct
cause of grease or fluid reaching linings.
Grind or replace lining.