Pontiac FIREBIRD 1972 Service Manual page 445

SINGLE DIAPHRAGM POWER BRAKE-MORAINE 5A-9
Insert hydraulic cylinder push rod through reaction
retainer so that end of rod with small pilot protrudes
from flat side of reaction retainer.
Place power piston installer, J 21524, in vise and
position power piston with three lugs fitting into not-
ches in piston.
Install new O-ring seal on air valve in second groove
from valve operating rod end.
Wipe thin film of power brake lube on large O.D. of
floating control valve and on O-ring of air valve.
Press air valve
-
push rod
-
floating control valve
assembly, air valve first, to its seat in tube of power
piston.
Place floating control valve retainer over push rod so
that flat side seats on floating control valve.
Start floating control valve and its retainer into
power piston hub. Use tool J 2 1601 to press floating
valve to seat in tube by placing tool on top of retainer
and pressing down.
Position push rod limiter washer over push rod to
floating control valve and install air filter element
over end of push rod and into power piston hub.
Install felt silencer and retaining clip in end of power
piston hub.
Assemble power piston diaphragm to support plate
from side of plate opposite locking tangs and press
raised flange of diaphragm through hole in center of
plate.
NOTE: Be sure that edge of center hole fits into
groove in flange of diaphragm.
Pull diaphragm away from O.D. of support plate so
that the plate can be gripped with hands. Wipe power
brake lubricant on all surfaces of small bead of dia-
phragm which contacts power piston.
Holding support plate on bare metal, with locking
tangs down, place support plate and diaphragm as-
sembly down over hub of power piston. Flange of
diaphragm will fit into groove on power piston.
Press down and rotate support plate clockwise until
lugs on power piston come against stops on support
plate.
Invert assembly and place in padded vise with power
piston hub end down and insert snap ring on air valve
using snap ring pliers.
Fig. 5A-10 Removing Air Valve
16. Install air valve spring retainer so that it seats on snap
ring and assemble reaction bumper into groove in end
of air valve.
17. Position reaction spring on spring retainer.
18. Position three reaction levers in slots on power pis-
ton. Narrow ends will rest on reaction spring.
19. Position reaction plate, with numbered side up, on
top of reaction levers and press down on plate until
large ends of reaction levers pop up and plate rests
flat on levers. Be sure that reaction plate is centered.
20. Place small end of hydraulic push rod in hole in
center of reaction plate, and line up ears on reaction
retainer with notches in power piston and push reac-
tion retainer down until ears seat in notches.
21. Maintain pressure on reaction retainer and position
large lock ring down over master cylinder push rod
so that one end of lock ring goes under lug on power
piston raised divider.
NOTE: Lock ring is positioned around power
piston so that it goes alternately over ear of
reaction retainer and under Jug ofpo wer piston
until end of nng is seated under lug with raked
divider.
CAUTION: Make sure that both ends of lock
ring are securely under large Jug.
22. Remove power piston assembly from vise. Install
large foam air filter ring over neck of power piston
hub.