GMC 1982 Light Duty Truck, Service Manual

Page: 1196 / 1435

7B3-12 89M M MANUAL TRANSMISSION
F ig . 7 B 3 - 2 3 ~ S id e C o v e r B o lt Id e n tific a tio n
M A IN S H A F T
Assembly
1. Slide second gear over mainshaft (synchronizer cone
toward rear) and down against shoulder on shaft. Refer
to Fig. 7B3-15.
2. Slide lst-2nd synchronizer assembly (including stop
ring with lugs indexed in hub slots) over mainshaft,
down against 2nd gear cone and secure with a new snap
ring. Slide next stop ring over shaft and index lugs into
clutch hub slots. Refer to Fig. 7B3-15.
3. Slide first gear (synchronizer cone toward clutch sleeve
gear just installed) over mainshaft into position against
clutch sleeve gear.
4. Install mainshaft bearing retainer ring, followed by
mainshaft rear bearing. Using an arbor and a suitable
tool, drive or press bearing down into position. Install a
new snap ring on shaft to secure bearing. Refer to Fig.
7B3-14. This snap ring is a select fit for minimum end
play.
5. Install partially assembled mainshaft into extension
housing far enough to engage bearing retaining ring in
slot in extension housing. Expand snap ring with pliers
so th at mainshaft ball bearing can move in and bottom
against its th ru s t shoulder in extension housing.
Release ring and seat it all around its groove in
extension housing. Refer to Fig. 7B3-13.
6. Slide overdrive gear over mainshaft (with synchronizer
cone toward front) followed by O / D gear stop ring.
7. Install 3 r d - 0 / D synchronizer clutch gear assembly on
mainshaft (shift fork slot toward rear) against O /D
gear. Be sure to index rear stop ring with clutch gear
struts. Install retaining snap ring. Refer to Fig. 7B3-12.
8. Using grease, position front stop ring over clutch gear,
again indexing ring lugs with struts.
T R A N S M IS S IO N
Assembly
1. Place the transmision case on its side with the shift
cover opening toward the assembler.
2. Install countergear assembly into the case aligning the
tangs on the front washer with the slots in the case.
Next install the rear washer aligning the tans with the
slot at the rear of the case and then let the countergear
rest in the bottom of the case. (Be sure thrust washers
stay in position). Refer to Fig. 7B3-9).
3. Coat a new extension gasket with grease, then place it
in position on the extension.
4. Insert mainshaft assembly into the case tilting it as
required to clear the countershaft gear.
5. Rotate the extension housing to expose the rear of the
countershaft bore. Install one bolt to hole the extension
in inverted position and prevent it from moving
rearward. Refer to Fig. 7B3-7.
6. Install drive gear assembly through the front of the
case and position it in the front bore. Install outer snap
ring in bearing groove. Tap lightly into place using a
soft faced hammer. If everything is in proper position,
the outer snap ring will bottom onto the case face
without excessive effort. If not, check to see if a strut,
roller bearing, or a stop ring is out of position.
7. Raise the countergear assembly into position with the
teeth meshed with the drive gear. Make sure thrust
washer remain in position on ends of the arbor and
tangs are aligned with slots in case.
8. S tart the countershaft into the rear bore of the case and
push forward until the shaft is approxim ately half way
through the gear. Install woodruff key and push the
shaft forward until end is flush with case. Remove
arbor Tool J-29793.
9. Install reverse shift lever shaft in case bore followed by
greased " O " ring and retainer.
10. Remove extension housing bolt and rotate extension to
provide clearance for installation of the reverse idler
gear in end of case.
1 1. Push the shaft in far enough to position reverse idler
gear on protruding end of shaft with fork slot toward
rear. At the same time, engage slot with reverse shift
fork.
12. Install woodruff key on shaft and drive shaft in flush
with end of case.
13. Align extension housing to case and install bolts.
Torque housing bolts to specifications.
14. Install drive gear bearing retainer and gasket. Coat
threads with sealing compound, then install bolts and
torque to specifications.
15. Install new expansion plug coated with sealing
compound in countershaft bore at front of case.
16. Position both synchronizer sleeves in neutral. Place the
1-2 shift fork into the groove of the 1-2 synchronizer
sleeve. Slide reverse idler gear to neutral.
17. Rotate each shift lever to neutral position (straight up)
and install 3rd/overdrive shift fork into its bore and
under both interlock levers.
18. Position side cover gasket on case using grease to
retain it. Install reverse d etent ball followed by the
spring into its bore in the case.
19. Lower the side cover onto the case guiding the 3rd/
overdrive shift fork into its synchronizer groove, then
lead the shaft of the 1-2 shift fork into its bore in the
side cover. Hold the reverse interlock link against the
1-2 shift lever to provide clearance as the side cover is
lowered into position. To finish the installation of the
side cover, use a screw driver and raise the interlock
lever against its spring tension to allow the 1-2 shift
fork to slip under the levers. Be sure the reverse
detent spring is positioned in the c o v er bore.