Chevrolet 1977 10 Series, Repair Manual, Page: 172 / 468

5-6 OVERHAUL MANUAL
vise. Position the prim ary power piston so th at the two radial
slots in the piston fit over the ears (tangs) of the tool (fig.
5-8A).
15. Fold the prim ary diaphragm away from the O.D. of
the prim ary support plate.
16. Holding the edges of the support plate, with the
locking tangs down, place the prim ary support plate and
diaphragm assembly over the tube of the prim ary power
piston. The flange on the I.D . of the prim ary diaphragm will
fit into a groove in the prim ary power piston.
17. G rip the edges of the prim ary support plate, press
down, and rotate clockwise until the tabs on the prim ary
power piston contact the stops on the support plate (fig. 5-
9A).
18. Place the power head silencer on the tube of the
prim ary power piston so that the holes at the base of the tube
are covered.
19. Apply silicone lubricant to the O.D. of the prim ary
power piston tube.
20. Remove the prim ary piston assembly from Tool J-
23101 and lay it aside.
21. Assemble the secondary diaphragm to the secondary
support plate from the side of the support plate opposite the
locking tangs. Press the raised flange on the I.D. of the
diaphragm through the center hole of the support plate. Be
sure that the edge of the support plate center hole fits into
the groove in the raised flange of the diaphragm. Apply a thin
coat of silicone lubricant to the I.D. of the secondary
diaphragm and the raised surface of the flange (that fits into
a groove in the secondary power piston).
22. M ount Tool J-23101 (with large diam eter end up)
in a vise. Position the secondary power piston so that the
radial slots in the piston fit over the ears (tangs) of the tool.
Apply a light coat of silicone lubricant to the tube of the
secondary power piston (fig. 5-4A).
23. Fold the secondary diaphragm away from the O.D.
of the secondary plate.
24. Holding the edges of the support plate with the
locking tangs down, place the secondary diaphragm and
support plate assembly over the tube of the secondary power
piston. The flange on the I.D. of the secondary diaphragm
will fit into the groove in the secondary piston.
25. G rip the edges of the secondary support plate, press
down, and rotate counterclockwise until the tabs on the
secondary power piston contact the stops on the support
plate. Fold the secondary diaphragm back into position on
the secondary support plate. Leave the secondary power
piston assembly on Tool J-23101 in the vise (fig. 5-6A).
26. Apply a light coat of talcum powder or silicone
lubricant to the bead on the O.D. of the secondary
diaphragm. This will facilitate reassembly of front and rear
housings.
27. Hold the housing divider so that the formed over
flange (that holds the prim ary 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.
28. Lubricate the I.D. of the secondary bearing with
silicone lubricant.
29. Position secondary Bearing P rotector Tool J-23188
on the threaded end of the secondary power piston (fig. 5-
13 A).
30. Hold the housing divider so that the six oblong
protrusions on the middle of the divider are facing up. Press
the divider down over the tool and onto the secondary power
Fig. 5-1 3 A -P o s itio n in g H o u sin g D iv id e r Over
S e c o n d a ry B e a rin g P ro te c to r T o o l J -2 3 1 8 8
piston tube where it will rest against the diaphragm support
ring. Remove Tool J-23188 from secondary power piston;
however, do not remove the secondary power piston sub-
assembly from Tool J-23101.
31. Pick up the prim ary power piston assembly and fold
the prim ary diaphragm away from the O.D. of the prim ary
support plate.
32. Position the small end of the air valve return spring
on the air valve so that it contacts the air valve retaining ring.
33. Position the prim ary power piston on the tubular
portion of the secondary power piston, making sure that the
air valve return spring seats down over the raised center
section of the secondary piston.
34. G rip the edge of the prim ary support plate, press
down, and start the threads on the secondary power piston
into the threaded portion of the prim ary power piston by
rotating in clockwise direction (fig. 5-5A).
35. Continue to tighten the prim ary power piston until
it is securely attached (approxim ately 5-15 ft. lbs.) to the
secondary power piston.
36. Fold the prim ary diaphragm back into position on
the prim ary support plate and pull the diaphragm O.D. over
the formed flange of the housing divider. Check that the bead
on the diaphragm is seated evenly around the complete
circumference.
37. Wipe a thin film of silicone lubricant on the O.D.
of the piston rod retainer. Insert the m aster cylinder piston
rod retainer into the cavity in the secondary power piston so
that the flat end bottom s against the rubber reaction disc in
the bottom of the cavity.
Rear Housing Group
1. Place the N EW prim ary power piston bearing in the
rear housing center hole so th at the formed flange of the
housing center hole fits into the groove of the seal. The thin
lip of the bearing will protrude to the outside of the housing.
2. Coat the I.D. of the prim ary power piston bearing
with silicone lubricant.
Final Assembly
1. M ount Holding Fixture J-22805 in a vise and position
the front housing on the tool so th at the housing studs fit in
the holes provided in the tool.
2. Position the power piston return spring over the inset