Chevrolet 1977 light duty truck, Service Manual

Page: 406 / 861

5. Fully release p ark in g brake and rotate the rear
wheels. N o d ra g should be present.
6. Remove vehicle from hoist.
A d justm en t-O rsch eln Lever Type
1. T u rn adjusting knob on parking brake lever
counterclockwise to stop.
2. Apply p ark in g brake.
3. Raise vehicle on a hoist.
4. Loosen nut at in te rm e d ia te cable equalizer and
then adjust nut to give light d ra g at rear wheels.
C A U T IO N :
See "C a u tio n " on Page I o f this
section.
5. Readjust parking brake lever knob to give a
definite snap-over-center feel.
PARKING BRAKE (PROPELLER SHAFT)-
INTERNAL EXPANDING
Adjustm ent-Drum On
1. Jack up at least one re a r wheel. Block wheels
and release h a n d brake.
2. Rem ove cotter pin and clevis p in connecting
pull rod and relay lever. This will assure freedom for full
shoe release.
C A U T IO N : I t m ay be necessary to knock out
lanced area in brake drum with p u n ch and
ham m er to gain entry into adjusting screw
through brake drum. Be sure all m etal has been
rem oved fr o m p a rkin g brake com partm ent.
3. Rotate brake d rum to bring one o f access holes
into line with adjusting screw at bottom o f shoes
( m a n u a l tran sm issio n ), top o f shoes (au to m atic
transmission).
4. E xpand shoes by rotating adjusting screws with
screwdriver inserted thro u g h hole in drum . Move outer
end o f screwdriver away from drive shaft. C ontinue
a d ju stm en t until shoes are tight against d ru m and drum
c an n o t be rotated by hand. Back off adjustm ent ten
notches and check d rum for free rotation.
5. Place p a rk in g brake lever in fully released
position. Take up slack in brake linkage by pulling back
on cable just enough to overcome spring tension. Adjust
clevis o f pull rod o r front cable to line up with hole in
relay levers.
a. Insert clevis pin and cotter pin, then tighten
clevis locknut.
b. Install a new metal hole cover in drum to
prevent co n ta m in a tio n o f brake.
c. Lower re a r wheels. Remove ja c k and wheel
blocks.
C A U T IO N :
See " Caution" on Page I o f this
section.
Adjustm ent -Drum Off
1. W ith p ark in g brake d ru m off, use special Tool
J-21177 or J-22364, D rum to Brake Shoe Clearance
G au g e, to check d ia m e te r o f d rum clearance surface.
2. T u rn the tool to the opposite side and fit over
brake shoes by turning the star wheel until the gauge just
slides over the linings.
3. Rotate the gauge around the brake shoe lining
surface to insure p ro p e r clearance.
4. Install propeller shaft flange at m a in sh a ft as
outlined in transmission section.
5. Lower re a r wheels. Remove jack and wheel
blocks.
PARKING BRAKE CABLES
Front Parking Brake Cable Replacement
1. Raise vehicle on hoist.
2. Remove adjusting nut from equalizer.
3. Remove retain er clip from rear portion o f front
cable at fram e and from lever arm.
4. Disconnect front brake cable from parking
brake pedal or lever assemblies. Remove front brake
cable. On some models it m ay assist installation o f new
cable if a heavy cord is tied to o th e r end o f cable in
order to guide new cable through p ro p e r routing.
5. Install cable by reversing removal procedure.
6. Adjust p ark in g brake.
Center Parking Brake Cable Replacement
1. Raise vehicle on hoist.
2. Remove adjusting nut from equalizer.
3. U nhook connector at each end and disengage
hooks and guides.
4. Install new cable by rev ersin g rem oval
procedure.
5. Adjust parking brake.
6. Apply park in g brake 3 times with heavy
pressure and repeat adjustment.
Rear Parking Brake Cable Replacement
1. Raise vehicle on hoist.
2. Remove re a r wheel and brake drum.
3. Loosen adjusting nut at equalizer.
4. D isengage r e a r cable at connector.
5. Bend retainer fingers.
6. Disengage cable at brake shoe operating lever.
7. Install new cable by rev ersin g rem oval
procedure.
8. Adjust parking brake.
COMBINATION VALVE
Testing Electrical Circuit of Com bination Valve
1. Disconnect wire from switch te rm inal and use a
ju m p e r to connect wire to a good ground.
2. Turn ignition key on " O n " - w arn in g lamp
should light. If lamp does not light, bulb is burned out or
electrical circuit is defective. Replace bulb or repair
electrical circuit as necessary.
3. W hen w arn in g lam p lights, turn ignition switch
off. Disconnect j u m p e r and reconnect wire to switch
terminal.
Testing W arning Light Switch Portion of
Com bination Valve
1. Raise vehicle on hoist. Attach a bleeder hose to