Chevrolet 10 series 1973, Overhaul Manual

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5 -1 6 BRAKES
POWER PISTON GAUGING
REMOVE RUBBER REACTION DISC, PISTON ROD RETAINER & AIR VA LVE SPRING FOR GAUGING
REACTION
PISTON
SECONDARY POWER CORRECT
PISTON
PRIMARY POWER
PISTON
(REAC TIO N PISTON TOO SHORT) (REACTIO N PISTON TOO LONG)
AIR V A L V E -P U S H ROD ASSEMBLY
J23337
REACTION PISTON
“ NOSE”
INCORRECT
Fig. 13B--Power Piston Gauging
permitting the outer edges of the gauge to
remain seated on the larger cavity of the
secondary power piston.
f. If the reaction piston is too long, the higher level
of the gauge will not clear the "nose" without
moving the outer edges of the gauge off the seat
in the large cavity of the secondary power
piston. If the reaction piston is too short, both
levels of the gauge will clear the "nose" of the
reaction piston. If either condition exists, a
separate kit of three selective reaction pistons
(differing in length and color) must be obtained
to permit use of piston to meet correct size
requirements of step (e) above.
NOTE: Care must be taken to insure that the
gauge is not cocked during gauging
procedure.
8. After determination of the correct reaction piston,
apply a light film of Delco Silicone Lube #5459912
(or equivalent) to the O.D. of the rubber reaction
disc.
9. Place the rubber reaction disc in the large cavity of
the secondary power piston and push the disc down
to seat on the reaction piston.
10. Unlock the secondary power piston from the
primary power piston.
11. Assemble the primary diaphragm to the primary
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. Lubricate the
diaphragm I.D. and the raised surface of the flange
(that fits into a groove in the primary power piston)
with a light coat of Delco Silicone Lube #5459912
(or equivalent).
12. Mount Tool J-23101 (small diameter end up) in a
vise. Position the primary power piston so that the
two radial slots in the piston fit over the ears (tangs)
of the tool (fig. 8B).
13. Fold the primary diaphragm away from the O.D.
of the primary support plate.
14. Holding the edges of the support plate, with the
locking tangs down, place the primary support plate
and diaphragm assembly over the tube of the
primary power piston. The flange on the I.D. of the
primary diaphragm will fit into a groove in the
primary power piston.
15. Grip the edges of the primary support plate, press
down, and rotate clockwise until the tabs on the
primary power piston contact the stops on the
support plate (fig. 9B).
16. Place the power head silencer on the tube of the
OVERHAUL MANUAL