Chevrolet 30 Series 1967 Service Manual page 401

REMOVAL FROM VEHICLE
1. Drain lubricant from transmission.
2. Disconnect the speedometer cable from speedometer
driven gear fitting and disconnect shift control rods
from the shifter levers at the transmission.
3. Remove the propeller shaft as outlined in Section 4.
4. Remove the 2 top transmission to clutch housing cap
screws and insert 2 transmission guide pins, Tool
J-1126 in these holes.
5. Remove the 2 lower transmission to clutch housing
cap screws.
. Slide the transmission straight back on guide pins
6
until the clutch gear is free of splines in the clutch
disc.
NOTE: The use of the 2 guide pins during this
operation will support the transmission and pre­
vent damage to the clutch disc through springing.
7. Remove transmission from under the body.
General Description.........................................................
Maintenance and Adjustments..........................................
Governor Switch and P i n io n .......................................
Sun Gear Solenoid, Oil Seal & Control Cable Bracket .
Case Rear Oil S e a l......................................................
Control Shaft Lever and/or "O " Ring Oil Seals . . . .
Speedometer Driven G e a r ..........................................
Electrical Unit C hecks................................................
Overdrive Relay ...................................................
A ir G ap ...............................................................
Point O p e n in g ...................................................
The overdrive unit is essentially a two-speed planetary
transmission attached to the rear of a fully synchronized
three-speed transmission. In overdrive, engine speed is
approximately 30 per cent slower at a given road speed
since the drive train includes planetary gears which pro­
vide a lower overall gear ratio than that obtained in high
gear with the conventional transmission.
The electrical equipment which controls the automatic
action of the mechanical portion of the overdrive unit
consists of a solenoid, a speed-sensitive governor switch,
a relay and a kickdown switch. The circuit including this
equipment makes it possible to operate in overdrive
above a pre-set cut-in speed, or in conventional drive at
any speed.
SERVICING THE OVERDRIVE
With the overdrive assembly removed from the trans­
SERVICE OPERATIONS
TRANSMISSION OVERDRIVE
IN D EX
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GENERAL DESCRIPTION
CLUTCHES AND TRANSMISSIONS 7-15
INSTALLATION IN VEHICLE
1. Install guide pins, Tool J-1126, in upper transmis­
sion to clutch housing bolt holes for alignment and
place transmission on guide pin. Start clutch gear
shaft into clutch disc and slide transmission forward.
2. Install the two lower transmission mounting bolts and
lock washers and tighten securely. Remove guide pin
and install upper mounting bolts and lockwashers and
tighten securely.
3. Install propeller shaft.
U-bolts and nuts which retain rear trunnion bearings
to pinion flange and tighten securely.
4. Connect first and reverse and second and third con­
trol rods to shifter levers at side cover.
5. Check and adjust linkage as necessary as outlined
under "Maintenance and Adjustments".
. Remove speedometer driven gear and add 1/2 pint
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transmission lubricant to housing. Reinstall speed­
ometer driven gear.
7. Connect speedometer cable to driven gear and tighten
securely.
. F ill transmission with lubricant (1 1/2 pts.).
8
Closing V o ltage...................................................
S o le n o id ..................................................................
Closing Coil ......................................................
Engaging Spring ................................................
Ignition Grounding Contact.................................
Governor S w itch ......................................................
Kickdown Sw itch ......................................................
Linkage A djustm ent................................................
Diagnosis - O v e rd riv e ......................................................
M e c h a n ic a l..................................................................
E le c tric a l............................................................ ... . .
mission, service operations on the transmission proper
are the same as for the passenger car three-speed
transmission.
Repairs to the overdrive housing, output shaft, ring
gear assembly, clutch cam, roller retainer, pinion cage,
sun gear, shift rail, sun gear control plate, output shaft
bearing, oil seal, speedometer drive gear, solenoid pawl
and interlock plunger may be performed underneath the
vehicle, if so desired, by removing the overdrive housing
without disturbing the transmission. Refer to Passenger
Overhaul Manual for Service Procedure.
If the transmission mainshaft, overdrive adapter or
transmission rear bearing which is retained in adapter
require replacement, the entire transmission and over­
drive assembly should be removed and overhauled on the
bench.
Align yokes and install
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CHEVROLET TRUCK SFP.VICE MANUAL