Chevrolet 70 1969 Series, Shop Manual

Page: 196 / 913

BRAKES 5A-3
Figure 2— Type “F” Brake Adjustment
The need for bleeding air from system is gen­
erally indicated by a springy, spongy pedal action.
The presence of air in system is a result of low
fluid level in master cylinder, or of some part of
the system having been disconnected. Bleeder valves
are provided on power cylinder (some models),
master cylinder (some models) and at wheel cyl­
inders. Type " F ” front brakes have two cylinders
per wheel and each has a bleeder valve. Type
"FR- 3” rear brakes have two cylinders per wheel
with a bleeder screw at the top cylinder only. R e ­
fer to figure 4 for bleeding sequence by truck model.
Master cylinder is accessible under the hood
on conventional models, through access door in
seat riser on tilt cab models. Bleeder valves at
wheel cylinders are accessible at inner sides of
the backing plates.
Figure 3 — Type “FR-3” Brake Adjustment
It is recommended that brake system be bled
in a definite sequence to obtain best results. Fig­
ure 4 illustrates various combinations of brake
equipment used, with bleeder valves numbered in
the recommended sequence in which they should
be bled.
There are two methods of bleeding hydraulic
brake systems used on these vehicles; pressure
bleeding and manual bleeding. Both are acceptable
and adequate but pressure bleeding is recommend­
ed, if equipment is available.
C A U T IO N : Before starting pressure bleeding
operations, stop engine and destroy vacuum in
system before opening any bleeder valve.
PRESSURE B L E E D IN G
Refer to figure 4 for bleeding sequence.
1. Make sure fluid level in pressure tank is
up to petcock above outlet and that tank is charged
R e vise d 1968
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH O P M A N U A L