Pontiac tempest 1968 Service Manual page 169

5-4 1968 P O N T I A C SERVICE M A N U A L
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.
R E P L A C E
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.
S C R E W D R I V E R
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.