5-4 1968
PONTIAC
SERVICE
MANUAL
pedal fully released (up) adjust switch by pushing
body through mounting
sleeve
so that plunger is fully
depressed against pedal arm.
CAUTION;
If pedal bracket prevents
full
return
of
brake pedal and master cylinder push rod, the
master cylinder pistons may be prevented from
returning
to their stops
B
This
can block off the
compensating
ports which prevents brake shoes
from
returning fully when the pedal is released.
A
further complication which follows a blocked
compensating
port is
lining
drag
and complete
brake
burnup on the
first
prolonged
drive.
It is
necessary
that the primary cups be entirely
clear
of
the compensating ports to provide a safety fac-
tor
against normal rubber
swell
and expansion and
deflection
of body parts and pedal linkage.
STOP
LIGHT
SWITCH
REMOVE
1. Disconnect wires from switch.
2. Remove switch by pulling out of bracket.
REPLACE
1. Position
stop
light switch in bracket and push
in
to maximum distance.
2
e
Connect wires to switch.
3.
Brake
pedal arm
moves
switch to correct dis-
tance on rebound. Check if pedal is in full return
position by lifting slightly by hand.
Electrical
con-
tact should be made when the brake pedal is de-
pressed 3/8" to 5/8
M
from fully released position.
BRAKE
WARNING
LIGHT
CHECKING
PROCEDURE
1. Determine if bulb is functioning by depressing
parking
brake.
SCREWDRIVER
Fig.
5-4
Preparing
to
Back
Off
Adjusting
Screw
BACKING
INSERT
SMALL
SCREW
DRIVER
OR AWL
THROUGH
BACKING
PLATE
SLOT
AND
HOLD
ADJUSTER
LEVER
AWAY
FROM
SPROCKET
BEFORE
BACKING
OFF
BRAKE
SHOE
ADJUSTMENT
Fig.
5-5
Backing
Off
Adjusting
Screw
2
9
Check to make sure both master cylinder res-
ervoirs
are full.
3.
Open one wheel cylinder bleed screw in rear
brake
system. (Do not remove one from each sys-
tem.)
4. Depress brake pedal. Do not release pedal.
The
light should
come
on due to pressure difference
between
front and rear systems. Approximately
150-200
psi differential is
needed
to operate brake
light.
5. Close bleed screw. Release brake pedal. Re-
fill
rear reservoir, if needed.
NOTE:
Caution should be taken to prevent air
from
entering hydraulic system during checks on
switch.
The
recommended checking interval should be 24
months or
24,000
miles, any time major brake work
is
done
or any time a customer complains of exces-
sive pedal travel.
BRAKE
MECHANISM AND DRUMS
ADJUSTMENT
All
four brake
.
assemblies incorporate a
self-
adjusting mechanism to automatically adjust the
brake
shoes
when the car is operated in reverse. A
manual
adjustment is required only when brake
shoes
are
replaced or the length of the star wheel adjuster
has
been
changed during
some
other service opera-
tion.
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