Chevrolet 70 1969 Series, Shop Manual

Page: 434 / 913

T R A N SM ISSIO N S A N D CLUTCHES 7D-29
9
10
Push Rod Pivot
Cotter Pin
Push Rod Pivot Pin
Push Rod Boot
Push Rod
Piston Retainer
Plate Snap Ring
Pedal Return Spring
Secondary Piston
Seal
Piston
Primary Piston Seal
Seal Expander
11 Pedal Stop Set Screw
and Locknut
12 Piston Return Spring
13 Fluid Outlet Port
14 Main Cylinder Body
Casting
15 Bypass Port
16 Intake Port
17 Piston Retainer Plate
18 Pedal Pivot Pin Set
Screw
19 Pedal Pivot Pin
20 Pedal Lever
TPM-7498-l
Figure 14— Clutch Master Cylinder
(Tilt Cab M odels— 80)
VENT HOLES
BAFFLE
CAP VENT HOLES
BAFFLE
POSITION LEGS OF BAFFLE
PERPENDICULAR TO VENT HOLES
t
-1 0 0 7
Figure 15— Master Cylinder Fillers Cap Baffle
(Tilt Cab Models— 80)
M A IN T E N A N C E (A L L T Y P E S )
Filler cap or cover on all clutch master cyl­
inders is designed to vent the fluid reservoir
without permitting loss of fluid. A small baffle is
inserted into filler cap as shown in figure 15 on
all tilt cab model 80 cylinders only. Bypass port
between cylinder bore and reservoir and vent hole
in filler cap must be kept open to assure proper
clutch control. An obstructed bypass port will
prevent return of fluid to reservoir, preventing
full engagement of clutch. Bypass ports may be
obstructed by one of the following causes:
1. Clogged with dirt -- remove master cylin­
der and disassemble and clean all parts. Refer to
applicable section view of master cylinder when
assembling.
2. Swollen primary cup due to the use of
wrong fluid — service the master cylinder, drain
and flush entire clutch control system, and refill
with proper fluid.
3. Pedal binding on shaft, preventing full re­
turn of piston — free up and lubricate pedal.
4. Improper push rod adjustment -- adjust
push rod (if used).
M A S T E R C Y L I N D E R R E P L A C E M E N T
Instructions for replacing clutch master cyl­
inders on conventional or tilt cab models 70 are
the same as for brake master cylinders explained
in “ H Y D R A U L IC B R A K E S ” (SEC. 5A) of this
manual.
CLUTCH PEDAL STOP SCREW
ADJUSTMENT
(TILT CAB MODELS-80)
To provide complete and proper release of
clutch on these vehicles, full travel of the master
cylinder piston must be assured. This is deter­
mined by the position of pedal stop screw which
is located on cylinder body below the pedal (fig. 16).
The proper setting of stop screw is obtained
when head of screw is just flush with surface of
screw lock nut. After making adjustment, tighten
lock nut firmly.
NOTE
Regardless of clutch operation be­
ing obtained, the stop screw should be
positioned as directed previously.
MASTER CYLINDER REPAIR
The following procedures cover disassembly,
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH OP M A N U A L