Chevrolet 10 Series 1968, Service Manual

Page: 247 / 713

F ig . 25 —P -2 0 -3 0 Parking Brake Front C a b le Adjustment
PARKING BRAKE-PROPELLER SHAFT INTERNAL
EXPANDING TYPE
Internal expanding type parking brake is mounted at
rear of transmission. When used as an emergency brake,
at start of braking action, brake shoes are forced out
against drum by a lever—operated cam.
The self-
energizing action of both shoes then completes brake
application. See Figure 27.
Adjustment—On Vehicle
1. Jack up at least one rear wheel. Block wheels and
release hand brake.
2. Remove cotter pin and clevis pin connecting pull rod
and relay lever. This will assure freedom for full
shoe release.
NOTE:
It may be necessary to knock out lanced
area in brake drum with punch and hammer to
gain entry into adjusting screw through brake
drum. Be sure all metal has been removed from
parking brake compartment.
3. Rotate brake drum to bring one of access holes into
line with adjusting screw at bottom of shoes.
4. Expand shoes by rotating adjusting screw with screw
driver inserted through hole in drum. Move outer
end of screw driver away from drive shaft. Continue
adjustment until shoes are tight against drum and
drum cannot be rotated by hand. Back off adjustment
ten notches and check drum for free rotation.
5. Place parking brake lever in fully released position.
Take up slack in brake linkage by pulling back on
control lever just enough to overcome spring tension.
Adjust clevis of pull rod to line up with hole in relay
lever.
a. Insert clevis pin and cotter pin, then tighten
clevis locknut.
b. Install new hole cover in drum to prevent con­
tamination of brake.
c. Lower rear wheels. Remove jack and wheel
blocks.
Adjustment—Off Vehicle
a. With parking brake drum off, use special Tool
J-21177 or J-22364, Drum to Brake Shoe Clear­
ance Gauge, to check diameter of drum clear­
ance surface. (Fig. 28). (This should be .030"
clearance.)
CHEVROLET TRUCK SERVICE MANUAL