Chevrolet 10 Series 1970, Service Manual

Page: 249 / 671

BRAKES 5-11
Adjustm ent—On Vehicle
1. Jack up at le a s t one r e a r wheel. B lock wheels and
re le a s e hand brake.
2. Rem ove c o tter pin and c le v is pin connecting pull rod
and re la y le v e r . This w ill assure freed om fo r fu ll
shoe re le a s e .
NOTE: It may be n ecessary to knock out lanced
area in brake drum with punch and ham
T i e r
to
gain entry into adjusting screw through brake
drum. Be sure a ll m etal has been rem oved fro m
parking brake com partm ent.
3. Rotate brake drum to bring one o f a ccess holes into
line with adjusting s c re w at bottom o f shoes.
4. Expand shoes by rotating adjusting sc re w with s crew
d r iv e r in serted through hole in drum. M ove outer
end of s c re w d r iv e r away fro m d rive shaft. Continue
adjustment until shoes a re tight against drum and
drum cannot be rotated by hand. Back o ff adjustment
ten notches and check drum fo r fr e e rotation.
5. P la ce parking brake le v e r in fu lly relea sed position.
Take up slack in brake linkage by pulling back on
cable just enough to o verco m e spring tension. Adjust
c le v is o f pull rod o r front cable to line up with hole
in rela y le v e r s .
a. In sert c le v is pin and co tte r pin, then tighten
c le v is locknut.
b. Install new hole c o v e r in drum to prevent con­
tamination o f brake.
c. L o w e r re a r w heels. Rem ove jack and wheel
blocks.
HYDRAULIC BRAKE LINES
Hydraulic Brake Hose
These hoses req u ire no maintenance other than p e r i­
odic inspection fo r damage fro m road hazards o r other
like sou rces. See brake lin es under S e rvice O perations
fo r p ro p er installation o f brake lines.
NOTE: A l w a y s disconnect hydraulic brake
hoses at fram e bracket b e fo re hoses a re torqued
at the wheel cy lin d er. Make certa in that brake
hoses a re not tw isted.
Hydraulic Brake Tubing
Hydraulic brake tubing used on a ll trucks is a double
la y e r fle x ib le ste e l tubing which re s is ts c o rro s io n and
also stands up under high p re s s u re s developed when
brakes a re applied. Maintenance o f the tubing should con­
s is t o f a p erio d ic check on the tubing; esp e c ia lly , in the
event o f rattles and/or crim pin g o r slow leakage due to
p o ssib le stone dam age, loose connections, etc.
PARKING BRAKE-PROPELLER SHAFT INTERNAL
E X P A N D IN G TYPE (Fig. 2 3)
Internal expanding type parking brake is mounted at
re a r of transm ission. When used as an em ergen cy brake,
at sta rt o f braking action, brake shoes a re fo rced out
against drum by a le v e r —operated cam.
CHEVROLET TRUCK SERVICE MANUAL