Pontiac FIREBIRD 1972 Service Manual page 496

SECTION 5 E
DISC BRAKES
The following caution applies to one or more steps in the assembly proce-
dure of components in this portion of the manual as indicated at appropri-
ate locations by the terminology "See Caution on page 1 of this Section".
CAUTION: THIS FASTENER IS A N IMPORTANT A T;TACHING
PART IN THA T IT COULD AFFECT THE PERFORMANCE OF
VITAL COMPONENTS AND SYSTEMS, AND/OR COULD RE-
SUL T IN MAJOR REPAIR EXPENSE. IT MUST BE REPLACED
WITH ONE OF THE SAME PART NUMBER OR WITH A N
EQUIVALENT PART IF REPLACEMENT BECOMES NECES-
SAR Y. DO NOT USE A REPLACEMENTPAR T OF LESSER QUAL-
ITY OR SUBSTITUTE DESIGN TORQUE VALUES MUST BE
USED AS SPECIFIED DURING REASSEMBLY TO ASSURE
PROPER RETENTION OF THIS PAR T.
CONTENTS OF THIS SECTION
..............................
Trouble Diagnosis and Testing
5E-1 Lining Replacement
...............................................
5E-7
Testing Proportioning Section of Caliper Overhaul
...................................................
5E- 1 1
..............................................
Combination Valve 5E-1 Install Caliper
......................................................
5E- 12
..................................................
General Diagnosis.. 5E- 1 Bleeding Disc Brakes
............................................
5E-12
................................................
General Description 5E-3 Rotor Measurements
............................................
5E- 16
Operation
..................................................................
5E-4 Rotor Service
........................................................
5E-13
.................................................
Combination Valve
5E-5 Specifications
..........................................................
5E- 16
Lining Inspection
....................................................
5E-6
TROUBLE DIAGNOSIS AND TESTING
Since the car is equipped with drum-type rear brakes, also 2. Install "T" fitting on pipe to master cylinder. Con-
refer to Section covering drum brakes to diagnose brake nect one outlet of "T" to rear brake outlet and the
problems. other to a suitable pressure gauge.
TESTING PROPORTIONING VALVE
3. Have brakes applied and compare inlet and outlet
pressure readings.
Premature rear wheel lock-up may be caused by a mal-
4. When inlet pressure is 500 p.s.i., outlet pressure
function of the proportioning valve section of the combi-
should be 415-460 p.s.i. When inlet pressure is 600
nation valve. This portion of the valve may be tested as
p.s.i., outlet pressure should be 455-460 p.s.i.
follows:
5. If a malfunction exists, the entire combination valve
1. Remove brake pipes and install suitable pressure
must be replaced.
gauge at outlet to rear brakes (Fig. 5E-23).
EXCESSIVE PEDAL TRAVEL (Low Pedal)
CAUSE
1. Master cylinder fluid level low.
CORRECTION
1. Fill to proper level with approved fluid.