Chevrolet 30 Series 1967 Service Manual page 200

REAR SUSPENSION AND DRIVE LINE 4-42
Fig . 84 - Removing Autom atic Switch
Installation
1. Check the two lead wires on the housing terminals.
2. With the seal between the carrier and shift unit po­
sitioned correctly; slide the shift unit on the differ­
ential carrier studs with the torsion spring swivel
block inserted in the shift fork slot.
3. Install the stud nuts, tightening to 50-70 foot-pounds
torque.
4. F ill the shift unit to operating capacity with lubricant
as specified under "General Maintenance."
5. Check installation by making a "LO" and "HI" range
shift. Ignition must be turned on before check can be
made.
NOTE: The shift unit motor runs equally well
in either direction, however, if the lead wires
are reversed at the terminals on the shift unit,
the axle will shift to the opposite range of that
indicated on the control switch.
. Connect wire at plug.
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VACUUM CYLINDER DIAPHRAGM
Replacement
1. Remove clamps on hose connections at the vacuum
cylinder and slip hoses off the connecting fittings.
2. Remove the three retaining bolts and lock washers
retaining the vacuum cylinder assembly to the dif­
ferential ca rrier housing and remove the vacuum
cylinder assembly from the vehicle.
3. Remove the screws that attach the two halves of the
vacuum cylinder and remove the outer half.
4. Using two 1/2" open end wrenches, one to hold the
push rod inner nuts and the other to remove the outer
nut from the push rod, remove the diaphragm plates
and diaphragm.
5. Install new diaphragm and plates to push rod and
tighten the retaining nut securely.
NOTE: Apply Permatex around push rod hole
between diaphragm plates.
. Assemble outer half of vacuum cylinder to inner half,
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install retaining screws and tighten securely.
7. Install a new gasket and install the vacuum shifter
assembly on the differential carrier housing.
. Replace hose connections and install clamps.
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CAUTION:
Be careful not to transpose hose
connections.
9. Test operation of shifting mechanism in all speeds.
VACUUM CYLINDER OIL SEAL
Replacement
1. Remove clamps from hose connections and remove
hoses from fittings.
2. Remove the three lower retaining bolts and lock
washers that attach the vacuum cylinder to the dif­
ferential ca rrier housing and remove the vacuum
cylinder assembly from the differential carrier
housing.
3. Remove the two retaining bolts and lock washers at­
taching the vacuum cylinder to its housing and sepa­
rate the two assemblies.
4. Remove the screws that attach the two halves of the
vacuum cylinder and remove the outer half.
5. Remove the diaphragm plates, and shaft as an as­
sembly.
. Drive the old seal out of the housing.
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7. Soak new seal in engine oil to provide for initial lu­
brication. Coat outer diameter of seal with Perm a­
tex and replace it in the inner half of the cylinder
with the free side of the leather down and press it
into place with seal installer Tool J-0968.
. Assemble the diaphragm shaft assembly into the
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housing.
9. Install the outer cover, and retaining screws.
CAUTION: Install the cover with the vacuum
line connection aligned with the connection on the
lower outer cover.
10. Assemble the vacuum cylinder assembly into its
housing, install the two retaining bolts and lock
washers and tighten securely.
NOTE:
The felt seal and felt seal in the hous­
ing should be inspected for damage and replaced
when necessary.
11. Install the completed assembly to the ca rrie r housing
with new gasket and the three retaining bolts and lock
washers and tighten securely.
12. Replace the hose connections and install clamps.
13. Test the operation of the shifting mechanism in all
speeds.
CHEVROLET TRUCK SERVICE M ANUAL