Chevrolet 10 series 1973, Overhaul Manual

Page: 115 / 522

5 -1 2 BRAKES
8. Remove the reaction piston and reaction disc from
the center of the secondary power piston by
pushing down on the end of the reaction piston
with a small object, such as a pencil, wooden dowel
or metal rod (fig. 7B).
9. Remove the air valve spring from the end of the air
valve (if it didn’t come off during disassembly of
the power piston).
10. Mount Tool J-23101 in a vise (with small diameter
end up). Position the primary power piston so that
the two radial slots in the piston fit over the ears
(tangs) of the tool (fig. 8B).
11. Fold back primary diaphragm from the support
plate. Grip the edge of the support plate and rotate
in a counterclockwise direction to unlock the
primary support plate from the primary power
piston (fig. 9B).
12. Remove the primary diaphragm from the primary
support plate.
13. Remove the air filter from the tubular section of
the primary power piston.
14. Remove the power head silencer from the neck of
the power piston tube.
15. Remove the rubber reaction bumper from the end
of the air valve.
16. Using Snap Ring Pliers J-4880, remove the
retaining ring from the air valve (fig. 10B).
17. Remove the air valve-push rod assembly from the
tube end of the primary power piston. The
following removal method is recommended:
Place the primary power piston in an arbor press,
and press the air valve push rod assembly out the
bottom of the power piston tube with a rod not
exceeding 1/2" in diameter.
18. Removal of the air valve push rod assembly will
disassemble the control valve retainer.
19. Remove the "O" ring seal from the air valve.
Cleaning
Use denatured alcohol to clean all metal, plastic and
rubber parts of the power cylinder. Immerse parts in
cleaning fluid and use a hair brush to remove foreign
matter. Blow out all passages, orifices and valve holes.
AIR DRY and place cleaned parts on clean paper or
lint-free cloth. If slight rust is found on inside surface of
power cylinder housing, polish clean with crocus cloth or
fine emery cloth, then follow with a thorough cleaning as
outlined above.
CAUTION: Use of gasoline, kerosene, anti­
freeze alcohol or any other cleaner with even a
trace of mineral oil, will damage rubber parts.
Inspection
Wipe cleaning fluid from all parts and carefully inspect
each part for damage and wear. Inspect rubber parts for
Fig. 6B--Locking or U n locking Secondary Support
Plate and Secondary Power Piston
Fig. 7B -Removing Reaction Piston and Reaction Disc
From Secondary Power Piston
cuts, nicks and distortion. These rubber parts are the key
to control of air flow and should account for the majority
of troubles traceable to leakage. If there is any question
whatever as to serviceability of any part, replace it.
SECO NDARY
SUPPORT
PLATE
OVERHAUL MANUAL