Pontiac FIREBIRD 1972 Service Manual page 446

5A-10 1972 PONTIAC SERVICE MANUAL
POWER PISTON
INSTALL
1. Place new power piston bearing in center of rear
housing so that flange on center hole of housing fits
into groove of power piston bearing. Large flange on
power piston bearing will be on stud side of housing.
2. Liberally coat inside of power piston bearing with
power brake lube.
3. Wipe power piston hub with power brake lube.
4. Push hub of power piston through rear housing seal.
5. Wipe O.D. of reaction retainer with power brake
lube.
FRONT HOUSING
REPLACE
1. Place new front housing seal in center of front hous-
ing so that flat surface of cup lies against bottom of
depression in housing.
2. Install new vacuum check valve grommet.
3. Attach tool J 22805-01 to front housing. Lubricate
I.D. of support plate seal with power brake lube.
NOTE: It is important that the front shell be
started using only the hands, in order to make
sure the housings will be completely mated
after
assembl'
and to eliminate any possibility
of cutting the diaphragm.
4. Hold power piston return spring in position between
front housing and power piston, then start front
housing into final position with hands, making sure
that scribe marks align on front and rear shells (Fig.
5A-11).
5. Insert square channel tube in end of tool 1 22805-01,
and using a crescent wrench, turn front housing
clockwise until fully locked.
6. Remove all tools.
GAGING PROCEDURE
NOTE: GAGING IS TO BE PERFORMED
WITHOUT VA CUUM.
1. Place the gage J 22647 over the piston rod in a posi-
tion which will allow the gage to be slipped to the left
or right without contacting the studs (Fig. 5A-12).
The center section of the gage has two levels. The piston
rod end should always touch the longer section of the gage
which extends into the front housing. The piston rod end
should never touch the shorter section of the gage.
NOTE: Any variation beyond these Iimits must
be compensated for by obtaining service adjust-
Fig. 5A-1 1 Installing Front Housing
Fig. 5A-12 Push Rod Adjustment