Component Overhaul - GMC 1976 ZEO 6083 Maintenance Manual

Figure 30-Brake Pedal Assembly (Left Side)
5. Release end of cable from parking brake lever.
6. Compress the locking fingers and pull the rear
cable from the backing plate refer to Figure 29 .
BRAKE PEDAL REMOVAL
1 . Remove four screws from power lever control
mounting panel, and pull valves and panel out (fig-
ure 20).
MASTER CYLINDER OVERHAUL
DISASSEMBLY (FIGURE 32)
1 . Remove the small secondary piston stop screw
from the bottom of the front fluid reservoir of the
master cylinder .
2. Place the master cylinder in the vise so that the
lock ring can be removed from the small groove in
the I.D . of the bore . Remove the lock ring and pri
mary piston assembly . Remove the secondary piston,
secondary piston spring and retainer by blowing air
through the stop screw hole . If air is not available,
a piece of wire may be used . Bend approximately
1/4" of one end of the wire into a right angle. Hook
this end under the edge of the secondary piston and
pull the secondary piston from the bore .
NOTE :
The brass tube-fitting insert need not be
removed unless visual inspection indicates the
insert is damaged.
6. Remove brake pedal assembly .
COMPONENT OVERHAUL
BRAKES 5- 2 5
Figure 31-Brake Pedal Assembly (Right Side)
2 . Remove stop light switch from top of brake
pedal. If equipped with cruise control remove the
switch next to the stop light switch (figure 30) .
3 . Remove cotter pin from pin retaining power
booster clevis to brake pedal. Remove clevis pin (fig-
ure 21).
4. Remove bolts from each end of pedal assembly
(figure 31).
5 . Loosen left-hand brake lever pivot bracket.
3 . To replace a defective insert or check valve, the
following procedure should be practiced:
a. Place the master cylinder in a vise, so that
the outlet holes are up . Enlarge the outlet holes in the
tube seats using a 13/64" drill . Tap a 1/4"-20
thread in these holes. Place a heavy washer over the
outlet on the master cylinder and thread a 1/4"-20
x 3/4" hex head bolt into the tube seat . Tighten the
bolt until the tube seat is unseated .
b. A more preferable way to remove a defec-
tive insert involves use of a self-tapping screw and a
claw hammer. With a box-end or socket wrench,
thread a #6-32 x 5/8" long self-tapping screw into
the tube-fitting insert . Using the claw end of the
hammer, remove the screw and insert.
4. Remove the casting from the vise and inspect
the bore for corrosion, pits and foreign matter . Be