Chevrolet 70 1969 Series, Руководство по ремонту

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T RA N SM ISSIO N S A N D CLUTCHES 7D-30
cleaning, inspection and repair, and assembly of
components used in the clutch cylinder bore. Refer
to applicable master cylinder illustration.
D ISA SSEM B LY
1. Clean all dirt from outside of unit, using a
non-petroleum solvent.
2. Remove snap ring from groove in cylinder
bore.
3. Remove piston assembly, primary cup,
return spring and retainer assembly from clutch
cylinder bore.
4. Remove cover from cylinder housing.
C L E A N IN G
Immerse all parts in denatured alcohol and
wash thoroughly. Wipe small parts dry and blow
out inside of reservoir and cylinder bore. Make
sure intake and bypass ports in cylinder housing
and bleeder holes in piston are clean.
C A U T IO N : Do not use kerosene or gasoline for
cleaning master cylinder components.
INSPECTION A N D REPAIR
Master cylinder repair kits are available
which contain all the parts ordinarily required
when servicing master cylinders. Refer to applic­
able parts book for part number of repair kit. In
addition to replacement of parts contained in repair
kit, master cylinder should be inspected and re­
paired, if necessary, as follows:
1. Examine cylinder bore. If scored or rust­
ed, recondition by honing. Be sure to use proper
size hone. Clutch cylinder bore is 1-1/8-inch. Do
not hone more than necessary to remove scores and
smooth up cylinder. Remove burrs caused by
honing from around by-pass and intake ports.
2. Check piston fit in cylinder bore. Clearance
Figure 16— Master Cylinder Pedal Stop Adjustment
(Tilt Cab Models— 80)
between piston and cylinder wall should be within
0.001" to 0.006" when checked with feeler gauge.
A S SE M B L Y
1. Before assembling, coat inside of cylinder
bore and dip all internal parts in hydraulic brake
fluid.
2. Install components in clutch cylinder bore
as follows:
a. Install return spring in cylinder bore, large
diameter first.
b. Install primary cup in cylinder bore with
lip of cup toward outlet end. Make sure end of
spring seats inside the cup.
c. Insert piston and secondary cup into cyl­
inder bore, with open end of piston toward open
end of cylinder.
d. Press piston into cylinder bore, compress­
ing spring, and install snap ring in groove in bore.
N O T E : Install piston stop plate in cylinder
used on " R " Models.
Make sure snap ring is fully seated in groove.
3. Check clearance between edge of primary
cup and the bypass port in each cylinder as follows:
a. From inside the reservoir, insert a straight
wire (tag wire or any wire of approximately 0.010"
diameter) through the bypass port.
b. While moving the wire up and down in the
bypass port, push the piston in very gently until a
slight drag is felt on the wire. Check clearance
between end of piston and snap ring. Clearance
should be 0.035 inch minimum. If less than 0.035
inch, the wrong size cup or a swollen cup has been
installed, or the parts were improperly assembled.
Disassemble unit and reassemble, using the cor­
rect parts.
4. Install cover on cylinder reservoir.
CLUTCH CONTROL SLAVE CYLINDER
Clutch control slave cylinder assembly is
mounted at side of clutch housing or transmission.
When cylinder is pressurized it activates the mech­
anical clutch release fork or lever to disengage
clutch.
Components of cylinder consists of an alum­
inum piston with two captive block-type seals (fig.
17). The return of the piston on clutch apply is
provided for by the external return spring. Cylin­
der bore is of 15 /1 6 " diameter.
R E M O V A L
1. Remove return spring from clutch release
fork or lever.
2. Disconnect fluid line at slave cylinder.
3. Remove bolts retaining slave cylinder at
mounting, then remove cylinder assembly.
CHEVROLET SERIES 70 -80 H EAVY DUTY TRUCK SH O P M A N U A L