Chevrolet 70 1969 Series, Shop Manual

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T RA N SM ISSIO N S A N D CLUTCHES 7D-24
this manual are of three types. Application of cyl­
inders to truck models is explained later under
"Clutch Master Cylinders.”
The clutch slave cylinder is mounted to side
of clutch housing or the transmission.
MAINTENANCE
To maintain proper clutch operation the sys­
tem should be checked and serviced periodically
as stated below:
1. Maintain proper level of hydraulic fluid in
master cylinder. Refer to LU BR ICATION (SEC1. 0)
for recommended fluid and checking intervals. At
least once a year, drain and flush the entire clutch
system and refill with new fluid.
2. Inspect entire clutch system regularly for
fluid leakage. Leakage must be corrected immed­
iately.
3. Make sure return spring at slave cylinder
is not weak or broken.
4. Check and if necessary adjust clutch pedal
linkage. Instructions are explained later under
"Clutch Control Adjustments."
5. If clutch pedal action is springy or spongy,
it is an indication that air needs to be bled from
hydraulic system or adjustment is necessary.
6. Clutch release bearing, when equipped with
lubrication fitting or grease cup, must be lub­
ricated at regular intervals as directed in LUB­
R IC A T IO N (SEC. 0).
CLUTCH CONTROL ADJUSTMENTS
Adjustments are generally required due to
wear of parts, or whenever the master cylinder,
M o v e R elease Lever
or Fork Until
Resistance Is Felt
W e d g e
A d ju stin g N u t
Lock Nut
U liT lf
Push Rod
Force Push Rod
To Bottom In
S lave Cylinder
1 / 2 " Free Travel
H old W e d g e
A g a in st Lever
O r Fork
slave cylinder, or clutch assembly has been re­
placed.
To obtain proper clutch control operation, two
adjustment points are available: Master cylinder
push rod adjustment, and the slave cylinder push
rod adjustment. N O T E : Master cylinder push rod
adjustment is not required on tilt cab models 80.
Purpose of master cylinder push rod adjust­
ment is to insure full return of master cylinder
piston when foot is removed from pedal. If push
rod is adjusted too long, piston could restrict the
bypass port in cylinder, and clutch would not en­
gage fully, thereby causing clutch to slip. Too short
a push rod would result in excessive pedal free
travel before clutch starts to disengage.
Purpose of slave cylinder push rod adjustment
is to provide proper position of clutch release
bearing when the clutch is engaged.
N O T E : Slave cylinder push rod adjustment is
necessary when push rod clearance is reduced to
1 /4-inch. Proper clearance is 1 / 2-inch as shown
in figure 4.
N O T E : Before making adjustments, the hy­
draulic system must be free of air and the master
cylinder must be filled to 1/2-inch below filler
opening.
IM P O R T A N T : If clutch control adjustments
are to be made, A L W A Y S make adjustment at
jClutch a n d Brake
M aste r Cylinder
Figure 5— Access to Master Cylinder
Figure 4 —
Slave
Cylinder Push Rod Clearance (Tilt Cab Models— 70)
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK S H O f M A N U A L