GMC 1976 ZEO 6083 Maintenance Manual page 254

25 . Hold the housing divider so that the formed
lip (that holds the primary diaphragm) of the divider
faces down . Place the secondary bearing in the I .D .
of the divider so that the extended lip of the bearing
faces up . (figure 48)
26 . Lubricate the I.D . of the secondary bearing.
27 . Position Tool J-23188, on the threaded end of
the secondary power piston . (figure 49)
28 . Hold the housing divider with the formed lip
(that holds the primary diaphragm) facing up . Press
the divider down over the tool and onto the second
ary power piston tube where it will rest against the
diaphragm support ring . Remove Tool J-23188 from
secondary power piston . Do not remove the second-
ary power piston subassembly from Tool J-23101 .
29 . Pick up the primary power assembly and po-
sition the small end of the air valve return spring on
the air valve so that it contacts the air valve retaining
ring .
30 . Fold the primary diaphragm away from the
O.D . of the primary support plate.
31 . Position the primary power piston on the
tubular portion of the secondary power piston, mak-
ing sure that the air valve return spring seats down
over the raised center section of the secondary pis-
ton.
32 . Grip the edge of the primary support plate,
press down, and start the threads on the secondary
power piston into the threaded portion of the pri
mary power piston by rotating in a clockwise direc-
tion . (figure 39)
Figure 48-Installing Secondary Bearing
BRAKES
5- 3 5
Figure 49-Installing Housing Divider
33 . Continue to tighten the primary power piston
until it is securely attached to the secondary power
piston .
34. Fold the primary diaphragm back into posi-
tion on the primary support plate and pull the dia-
phragm O.D . over the formed lip of the housing
divider. Check that the bead on the diaphragm is
seated evenly around the complete circumference .
35 . Wipe a thin film of lubricant on the O.D . of
the piston rod retainer . Insert the master cylinder
piston rod retainer into the cavity in the secondary
power piston so that the flat end bottoms against the
rubber reaction disc in the bottom of the cavity .
36 . Place the primary power piston bearing in
rear housing center hole so that the formed flange of
Figure 50-Installing Primary Power Piston Bearing