Chevrolet 10 series 1973, Overhaul Manual

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BRAKES 5-9
DELCO MORAINE POWER BRAKE CYLINDER
DUAL DIAPHRAGM TYPE
INDEX
Disassembly...........................................................................................5-9
Cleaning................................................................................................. .5-12
Inspection...............................................................................................5-12
Assembly................................................................................................ 5-13
Gauging................................................................................................. 5-18
OVERHAUL OPERATIONS
Disassembly (Fig. IB )
NOTE: Scribe a mark on the top center of
the front and rear housings in line with
master cylinder reservoir cover to facilitate
reassembly.
1. Remove the two locknuts which hold the master
cylinder to the front housing, and remove the
master cylinder from the mounting studs.
2. Attach base of Holding Fixture J-22805 to front
housing with nuts and washers and draw down tight
to eliminate damage to studs. Clamp base in a
bench vise with the power section up (fig. 2B).
3. Separate front and rear housings as follows:
a. Straight Mounting Bracket and Chevelle (Fig.
2B) - Place Spanner Wrench J-9504 over studs
on rear housing and attach with nuts and
washers. Draw nuts down tight to eliminate
bending or damaging of studs.
b. Tilt Mounting Bracket Except Chevelle (Fig. 4A)
- Place Tool J-22893 inside tilted mounting bracket.
Place Spanner Wrench J-9504 on top of J-22893
and tighten nuts and washers, securing spanner
wrench.
WARNING: When separating housings, maintain pres­
sure on rear housing as it is under spring tension.
c. Press down on Spanner Wrench J-9504 and
rotate the rear housing counterclockwise to
separate the two housings. If the rear housing
cannot be readily loosened, tap the rear housing
lightly with a plastic hammer.
4. Remove Tools J-9504 and J-22893 from rear
housing (tilted mounting bracket type), Tool J-9504
on regular type.
CAUTION: Care must be exercised not to
damage or loosen studs in housing. Also, take
care that no pressure is brought to bear on
plastic power piston.
5. Lift the rear housing assembly from the unit.
Front Housing Group
1. Remove the power piston return spring. The
retainer plate may come out with the power piston
return spring. Remove the vacuum check valve and
grommet from the front housing if the check valve
is defective or the grommet cracked, cut or
damaged.
2. Remove the front housing seal.
Rear Housing Group
1. Remove the push rod clevis and locknut, if so
equipped.
2. Remove the boot retainer and boot from the rear
housing. Remove the felt silencer from inside the
boot.
3. Remove the power piston group from the rear
housing and remove the seal from the center
opening of the rear housing.
Power Piston Group
1. Lift the bead on the O.D. of the secondary
diaphragm and remove the diaphragm support ring
(fig. 3B).
2. If not already disengaged, remove the retainer plate
from the secondary piston. Remove the piston rod
retainer and piston rod from the secondary piston.
3. Mount double-ended Tool J-23101 (with large
diameter end up) in a vise. Position the secondary
power piston so that the two radial slots in the
piston fit over the ears (tangs) of the tool (fig. 4B).
4. Fold back primary diaphragm from the O.D. of the
primary support plate. Grip the edge of the support
plate and rotate counterclockwise to unscrew the
OVERHAUL MANUAL