GMC T Series 1994 Repair Manual page 839

gear to the range shift hub and mainshaft. Torque flow
continues through the slip yoke which is splined to the
mainshaft, and finally to the rear propeller shaft and
axle. The mode synchronizer remains in the neutral
position and does not lock the drive sprocket to the
mainshaft. As a result, torque is not transferred to the
driven sprocket.
In 4HI range, input torque from the input gear is
transmitted to the mainshaft in exactly the same fashion
as in 2HI range. However, in the 4HI position, the mode
synchronizer sleeve is shifted into engagement with the
clutch teeth of the drive sprocket. This locks the drive
sprocket to the mainshaft through the synchronizer.
EXTERNAL COMPONENTS
| Clean (Figures 3 and 4)
The transfer case exterior using solvent and a stiff
brush.
Remove or Disconnect
1. Front output yoke nut (77), washer (76), rubber
sealing washer (75), and front output yoke (74)
from the front output shaft.
2. Bolts (95) and encoder motor (94).
3. Vacuum switch (46) and O-ring seal (47).
4. Speed sensor (6) and O-ring seal.
5. Poppet screw (68), poppet spring (71), and poppet
plunger (70).
M AIN SHA FT EXTENSION AND
O IL PUMP HOUSING
+-► Remove or Disconnect (Figures 1, 3, and 4)
1. Rear extension bolts (3) and rear extension (4).
2. Bearing retainer snap ring (5) from the mainshaft
(19).
3. Pump retainer housing bolts (7).
4. Pump retainer housing (8) from the rear case half
(17).
5. Speedometer tone wheel (11) from the mainshaft
(19).
6. Case bolts (3) from the case halves.
• Note, the two longer case bolts and washers go
into the doweled case holes (33).
Important
Some transfer case models
to them by the case half bolts,
from the others and must be
holes.
• Separate the case halves
into the slots cast into the
Do not attempt to wedge
any point on the mating
case may result.
DISASSEMBLY
have a bracket attached
These bolts are different
put back into the correct
by inserting screwdrivers
case ends and pry apart,
the case halves apart at
surfaces. Damage to the
Torque is transmitted through the drive sprocket to the
driven sprocket by the connecting drive chain. The
torque flows through the front output shaft to the front
propeller shaft and axle resulting in high range
four-wheel drive.
In 4LO range, the path of torque through the transfer
case is exactly the same as in 4HI range but with one
major difference. In 4LO range the range shift hub is
shifted into engagement with the planetary carrier. This
causes the input gear to rotate the planetary pinions
inside the annulus gear, causing the planetary carrier,
range shift hub, and mainshaft to rotate at a gear
reduction ratio of 2.72:1.
• Be careful not to damage the oil pump (12)
(located in the rear case half) while removing
the rear case half (17).
INTERNAL COMPONENTS
Remove or Disconnect (Figures 3 through 8)
Tools Required:
J 8092 Driver Handle
J 36370 Bearing Installer/Remover
J 29170 Bearing Remover
J 29369-1 Bearing Remover
J 9276-21 Adapter
J 2619-01 Slide Hammer
J 33790 Bearing Remover
Important
The annulus gear found in this transfer case is not
serviceable or removable, and should only be replaced
as a unit with the front case half. If the annulus gear is
removed, damage will result to the case.
1. Oil pump (12), pickup tube (18), O-ring (14), and
pump pickup filter (35) from the rear case half (fig­
ure 5).
2. Fork shift spring.
3. Mainshaft (19), chain (58), and driven sprocket (22)
from the front case half (45) as a unit. Mode shift
fork (54) and shift rail (48) will be removed with the
mainshaft (figure 3).
4. Retainer (snap ring) (83) from the mainshaft (19).
5. Synchronizer assembly (81).
6. Drive sprocket (20) from the mainshaft (19) (figure
6
).
7. Range shift fork assembly (51) and range shift hub
(34) from the planetary carrier (36).
• It is necessary to rotate the sector shaft (55) to
obtain clearance when removing the range fork
(51) (figure 3).
8. Retainer (snap ring) (63), O-ring (64), and shift sec­
tor (55) from the front case half (45).
9. Input bearing retainer bolts (43) and input bearing
retainer (44) from the front case half (45).
10. Bearing retainer (snap ring) (39).
11. Planetary carrier (36) and the input gear (38) from
the annulus gear (62) using a soft faced hammer.