GMC T Series 1994 Repair Manual page 850

teeth of the drive sprocket. This locks the drive sprocket
to the mainshaft through the synchronizer. Torque is
then transmitted through the drive sprocket to the driven
sprocket by the connecting drive chain. Since the front
output shaft is splined to the driven sprocket, torque
flows through the output shaft to the front propeller
shaft and axle resulting in high range four-wheel drive.
EXTERNAL COMPONENTS
Clean
• The transfer case exterior using a solvent and a
stiff brush.
Remove or Disconnect (Figures 1 through 4)
1. Front output flange nut (77), washer (76), rubber
sealing washer (75), and front output flange (74)
from the front output shaft.
2. Four-wheel drive actuator switch (46) and O-ring
seal (47).
3. Speedometer sensor (9) and O-ring seal (85).
4. Poppet screw (68), O-ring seal (69), poppet spring
(71), and poppet plunger (70).
M AINSHAFT EXTENSION AND
OIL PUM P HOUSING
Remove or Disconnect (Figures 3 and 4)
1. Rear extension housing bolts (3) and rear exten­
sion (4).
2. Bearing retainer (snap ring) (5) from the mainshaft
(19).
3. Pump retainer housing bolts (7).
• Pump retainer bolts are shouldered.
4. Pump retainer housing (8) from the rear case half
(17).
38. Input Gear
44. Input Bearing Retainer
46. 4WD Actuator Switch
63. Shift Lever Nut
65. Shift Lever
74. Front Output Flange
In the 4LO range, the path of torque through the
transfer case is exactly the same as in the 4HI range
but with one major difference.
In the 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.
DISASSEMBLY
5. Retainer (snap ring) (10), speedometer tone wheel
(11), and retainer (snap ring) (10) from mainshaft
(19).
6. Case bolts (3) from case halves.
• Note two longer case bolts (16) and washers
(27) go into the doweled case holes (33).
• Separate the case halves. Insert two screwdrivers
into the slots cast into the case ends and pry apart.
Do not attempt to wedge the case halves apart at
any point on the mating surfaces.
• Be careful not to damage the oil pump (12)
(located in the rear case half) (17).
INTERNAL COMPONENTS
Remove or Disconnect (Figures 3 through 9)
Tools Required:
J 2619-01 Slide Hammer
J 8092 Driver Handle
J 22912-1 Bearing Remover
J 29369-1 Output Shaft Bearing Remover
J 29369-2 Output Shaft Bearing Remover
J 9276-21 Slide Hammer Adapter
J 33832 Bearing Installer/Remover