Chevrolet 10 series 1973, Overhaul Manual

Page: 125 / 522

5 2 2 BRAKES
CAUTION:
The use of gasoline, kerosene,
antifreeze, alcohol or any other cleaner, with
even a trace of mineral oil, will damage rubber
parts. Be particularly careful during reassem­
bly that no grease or mineral oil comes in
contact with these rubber parts.
Inspection
Wipe cleaning fluid from all parts and carefully inspect
each part for damage and wear. Inspect rubber parts for
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.
Refer to "Inspection Chart" for more detailed
instructions.
Assembly (Figs. 1C and 2C)
CAUTION:
Be sure to keep parts clean until
reassembly. Re-wash at reassembly if there is
any occasion to doubt cleanliness - such as
parts dropped or left exposed for eight hours or
longer.
I f there is any suspicion o f contamination or
any evidence of corrosion, completely flush the
car hydraulic brake system in accordance with
the Chassis Service Manual.
Lubricate rubber parts, all plastic and metal
friction points with Delco Silicone Lube
#5459912, or equivalent.
Front Housing Group
1. Install check valve grommet in front housing with
beveled edge of grommet inside of housing. Dip
check valve in clean denatured alcohol and install
in grommet—check valve stem is to be outside of
housing.
2. Position and secure Holding Fixture J-22805 (fig.
2A) to mounting studs, and place tool and front
housing in a vise. Be sure to align tool so that check
valve is not damaged.
NOTE: If either or both of the housings are
replaced, make sure alignment marks are
transferred to the new housing.
Rear Housing Group
1. Place rear housing on a block of wood, stud side
down, and position housing seal in center hole. Use
Tool J-22677 (fig. 4C) to seat seal in recess of rear
housing. Tool bottoms against housing when seal is
in place.
2. Assemble diaphragm plate assembly (see fig. 2C).
a. Apply Delco Silicone Lube #5459912 (or
equivalent) to outside diameter of diaphragm
plate and extension, to bearing surfaces of air
valve and to outer edge of valve poppet. Insert
air valve and push rod assembly in extension of
diaphragm plate.
NOTE: The air valve, poppet valve and push
rod are serviced as an assembly; a complete
unit must be installed if there is damage to
any of the component parts.
b. Depress the push rod slightly and install the air
valve lock. Make sure the lock indexes and
retains the air valve.
c. Install the rolling diaphragm in the groove of
diaphragm plate.
d. Apply Delco Silicone Lube #5459912 (or
equivalent) to surface of reaction disc and
position disc in center bore of diaphragm plate.
Use piston rod to seat disc in bore. Make sure
disc is fully seated before removing piston rod.
NOTE: If reaction disc is not fully seated, it
will result in an erroneous push rod height
adjustment.
3. Apply Delco Silicone Lube #5459912 (or equiv­
alent) to I.D. of rear housing seal and diaphragm
bead contact surface of rear housing. Install
diaphragm plate assembly in rear housing.
4. Place air filter element over psh rod and into
diaphragm plate extension. Install filter retainer.
Final Assembly
1. Attach base of Holding Fixture J-22805 to front
housing with nuts and washers and draw down tight
to eliminate bending or damage to studs. Clamp
base in bench vise with power section up (fig. 2A).
CAUTION:
Be sure to align tool so that the
check valve in the front housing is not
damaged.
2. 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.
3. Place diaphragm plate return spring in front
housing and position rear housing assembly on
front housing (small end of spring downward).
Position rear housing so that when housings are
locked, scribe marks on front and rear housings will
be in alignment.
4. Press down on Spanner Wrench J-9504 and rotate
the rear housing counterclockwise to assemble the
two housings (fig. 3A).
CAUTION:
Bend lances in on the rear housing.
I f the tangs crack or break during this
operation it will be necessary to replace that
half of the housing.
5. Remove Tool J-9504 from the rear shell.
6. Install air silencers over push rod end and then
install push rod boot. Install boot retainer.
OVERHAUL MANUAL