Chevrolet Chevelle 1977 Repair Manual page 185

Fig. 5-1 6C--G aging M a s te r C y lin d e r Push Rod
Final Assembly
1. Place air silencer over holes on tube of power piston.
Wipe tube of power piston with Delco Power Brake Lube (or
equivalent).
2. Assemble power piston to rear housing.
3. Wipe tube of reaction retainer with Delco Power
Brake Lube (or equivalent) and lay assembly aside.
4. A ttach base of Holding Fixture J-22805 to front
housing with nuts and washers and draw down tight to
eliminate bending or damaging of studs. Clamp base in a vise.
Place power piston return spring over the insert in the front
houisng.
5. Lubricate the I.D. of the support plate seal, the
reaction retainer tube and the beaded edge of the diaphragm
with Power Brake Lube (or equivalent).
6. Place the rear housing assembly over the front housing
assembly and align the scribe m arks of the two housings so
they will m atch when in locked position.
7. Assemble front and rear housings as follows:
Straight Mounting Bracket
a.
W rench J-9504 over studs on rear housing, and attach with
nuts and w ashers-draw nuts down tight to eliminate bending
or damaging of studs.
Tilt Mounting Bracket (Chevelle)
b.
Spanner W rench J-9504 to bracket with three bolts and nuts.
Draw nuts down tight to eliminate damage to the bracket.
BENDIX SINGLE DIAPHRAGM POWER BRAKE UNIT
Disassembly (Figs. 5-1D and 5-2D)
1. Scribe a line across front and rear housings to facilitate
reassembly.
2. Remove the front housing seal (fig. 5-2D); pulling the
piston rod from the front housing will also remove the seal
assembly. Remove the piston rod.
3. A ttach 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. 5-2A).
BRAKES
c.
Position Tool J-22893 inside tilted m ounting bracket. Place
Spanner W rench J-9504 on top of J-22893 and tighten nuts
and washers to bolts provided, securing Spanner W rench.
d. Press down on spanner wrench and twist rear housing
clockwise in relation to front housing until fully locked. Do
not break studs loose in rear housing or put pressure on
power piston tube when locking housings.
8. Remove Spanner W rench J-9504. Remove unit from
vise and remove Holding Fixture J-22805 from the front
housing.
9. Push felt silencer over push rod to seat against end
of power piston tube. Snap ring retainer is now placed on
push rod so it can hold silencer against power piston tube.
Plastic boot is now pushed to seat against rear housing.
Raised tabs on side of boot will locate in holes in center of
brackets.
10. Using a 1/8" diam eter rod (or similar tool), stake
the front and rear housing in two places 180° apart (figs.
5-14C and 5-15C).
CAUTION:
for staking a second time. Stake two o f the
remaining tabs. When all tabs have been staked
once, the housing
Gaging of Power Brake Unit
The following gaging operation is necessary only when
a major structural part such as front or rear housing, power
piston assembly, m aster cylinder piston or master cylinder
assembly is replaced with a new part. The gage measures how
far the master cylinder push-rod projects from front housing.
This dimension must be correct to insure proper clearance
in master cylinder between prim ary cup and compensating
port.
Make check as follows:
1. Place gage over piston rod in a position which will
allow gage to be slipped to left or right without contacting
studs.
The center section of gage has two levels. The piston rod
end should always touch the longer section of gage which
- Place Spanner
extends into front housing. The piston rod end should
touch the shorter section of gage (fig. 5-16C).
2. Any variation beyond these two limits must be
- Secure
compensated for by obtaining the service adjustable piston
rod, and adjusting the screw in end to match height of gage.
UNIT REPAIR
CAUTION:
valve in the front housing is not damaged.
4. Loosen locknut and remove push rod clevis and
locknut, if so equipped.
5. Remove the mounting bracket from the rear housing,
if so equipped.
6. Remove the dust boot retainer, dust boot and silencer
from the diaphragm plate extension.
7. The edge of the rear housing contains twelve lances.
Four of these lances (one in each quadrant) are deeper than
Tilt Mounting Bracket (Except Chevelle) -
The interlock tabs should not be used
must
be replaced.
Be sure to align tool so that the check
5-19
never