Chevrolet 70 1969 Series, Shop Manual

Page: 195 / 913

BRAKES 5A-2
Air Cleaner
Vacuum Gauge
Master Cylinder
Vacuum Line From Engine
(From Vacuum Pump on Diesel)
Brake Pedal
Vacuum Power Cylinder
Vacuum Line From Engine
to Control Valve
Hydraulic Line From
Master Cylinder
Hydraulic Line to Wheels
Atmosphere Line From
Air Cleaner
Figure J— Typical Vacuum and Hydraulic Lines Installed
accessible through openings in brake backing plate
or are external type.
N O T E : Wheel bearings must be properly ad­
justed before attempting to adjust brake shoes.
Refer to "HUBS A N D BEARINGS "(S E C . 3D for front
and SEC . 4C for rear).
Brake shoe adjustment points for front brakes
(Type "F ") are illustrated in figure 2. Adjustment
points for rear brakes (Type "FR-3") are shown
in figure 3.
T Y P E " F " (Fig. 2)
1. Jack up front end of vehicle until wheels
clear floor. Place wrench on one adjusting cam
stud to adjust one shoe. Rotate wrench in direction
of forward wheel rotation to decrease lining-to-
drum clearance. Reduce clearance until brake drag
is felt as wheel is turned in forward direction by
hand.
2. Move wrench slightly in opposite direction
until brake drag is relieved, then move wrench an
additional 7 to 10 degrees to provide running clear­
ance. (7 to 10 degrees is equal tol to 1-1/2 inches
of travel at end of an 8-inch wrench.)
3. Place wrench on opposite adjusting cam
stud and adjust second shoe by repeating steps 1
and 2 .
T Y P E "FR- 3" (Fig. 3)
1. Jack up vehicle until wheels are clear of
floor. Remove adjusting hole covers from backing
plate.
2. At one adjusting slot, insert adjusting tool
J-4707 or similar tool through slot and engage
adjusting wheel. Move tool toward axle to rotate
adjusting wheel and decrease lining clearance until
lining drags on drum.
3. Relieve drag by rotating adjusting wheel in
opposite direction. Back off adjustment as follows:
For worn lining - 3 notches (clicks)
For new lining - 5 notches (clicks)
4. At other adjusting slot, repeat steps 2 and
3 to adjust other shoe.
5. Install hole covers in backing plate.
BLEEDING BRAKES
Use only Hydraulic Brake Fluid recommended
in LU B R IC A T IO N (SEC. 0). When other than rec­
ommended fluid has been used, drain and flush the
entire hydraulic system, using clean alcohol or a
hydraulic brake system cleaning fluid. Disassem­
ble, clean, and inspect hydraulic units. Replace all
rubber parts. Refill system with recommended
fluid.
CHEVROLET SERIES 70 -80 H EAVY DUTY TRUCK SH O P M A N U A L