Pontiac FIREBIRD 1972 Service Manual page 497

5E-2 1972 PONTIAC SERVICE MANUAL
2. Poor quality brake fluid (low boiling 2. Drain hydraulic system and fill with approved
point) in system. fluid.
3. Air in hydraulic system.
3. Bleed hydraulic system and refill with approved
fluid.
4. Hoses soft or weak (expanding under
4. Replace defective hoses.
pressure).
5. Caliper seals soft or swollen. 5. Drain hydraulic system, flush system with
alcohol and replace all cups and seals in complete
brake system.
HARD PEDAL (Excessive Pedal Pressure Needed to Stop Vehicle)
CAUSE
1. Power brake malfunctioning.
2. Linings soiled with brake fluid, oil or grease.
3. Lines, hoses or connections dented, kinked,
collapsed or clogged.
'
4. Master cylinder cups swollen.
5. Master cylinder bore corroded or rough.
6. Caliper pistons frozen or seized.
7. Caliper cylinder bores corroded or rough.
8. Pedal push rod and linkage binding.
9. Meterihg valve not working.
CORRECTION
1. Check and repair power unit.
2. Replace shoes and linings.
3. Repair or replace defective parts.
4. Drain hydraulic system, flush system with
brake fluid and replace all cups and seals in complete
brake system.
5. Repair or replace master cylinder.
6. Disassemble caliper and free up pistons
(replace if necessary).
7. Disassemble caliper and remove corrosion or
roughness, or replace caliper.
8. Free up and lubricate.
9. Replace combination valve.
GRABBING OR PULLING (Severe Reaction To Pedal Pressure and Out of Line
Stops)
CAUSE
1. Linings soiled with brake fluid, oil or grease.
2. Caliper loose.
3. Lines, hoses or connection dented, kinked,
collapsed or clogged.
4. Master cylinder bore corroded or rough.
5. Caliper pistons frozen or seized.
6. Caliper cylinder seals soft or swollen.
7. Caliper cylinder bores corroded or rough.
8. Pedal linkage binding (and suddenly releasing).
9. Metering valve not functioning properly.
CORRECTION
1. Replace shoes and linings.
2. Tighten caliper mounting bolts to specified
torque.
3. Repair or replace defective parts.
4. Repair or replace master cylinder.
5. Disassemble caliper and free up pistons (replace
if necessary).
6. Drain hydraulic system, flush system with
brake fluid and replace all cups and seals in
complete biake system.
7. Disassemble caliper and remove corrosion or
roughness, or replace caliper.
8. Free up and lubricate linkage.
9. Replace combination valve.
FADING PEDAL (Pedal Falling Away Under Steady Pressure)
CAUSE CORRECTION
1. Poor quality brake fluid (low boiling point) in 1. Drain hydraulic system and fill with approved
system. fluid.
2. Hydraulic connections loose; lines or hoses 2. Tighten or replace defective parts.
ruptured (causing leakage).