Pontiac FIREBIRD 1972 Service Manual page 441

SINGLE DIAPHRAGM POWER BRAKE-MORAINE 5A-5
SUSPENDED
METAL PLATE
\
RUBBER DIAPHRAGM
RELEASING POSITION
APPLYING POSITION
BALANCED PRESSURE
(PARTIAL VACUUM
O N BOTH SIDES)
ATMOSPHERIC PRESSURE PUSHES
PLATE WHICH PUSHES ROD
TO MASTER CYLINDER
BLEEDING BRAKES
Fig.
5A-3
Simplified Power Brake Theory
MINOR SERVICE
Brakes should be bled in the same manner as non-power
brakes, see Section 5. Bleed with engine off and vacuum
reserve depleted.
STOP LAMP SWITCH
(See Section 5 for service.) All models use the same switch
for both standard and power brakes.
MASTER CYLINDER ONLY
REMOVE
Certain repair operations, such as replacement of master
cylinder internal parts, permits the master cylinder to be
removed by itself, leaving the power cylinder, pedd and
brackets in the car.
1. Disconnect hydraulic lines at master cylinder, pump
fluid from cylinder into a container and dispose of
fluid. Cover cylinder openings and ends of both pipes
to exclude dust, dirt, etc.
2. Remove master cylinder attaching nuts and remove
master cylinder from vacuum power section.
FRONT HOUSING
REMOVE
1. Remove vacuum check valve from front housing and
discard grommet.