GMC T Series 1994 Repair Manual page 876

4401 TRANSFER CASE
The Borg-Warner 4401 transfer case is a chain driv­
en, four-position unit providing four-wheel drive high
and low ranges, a two-wheel high range, and a neutral
position. The BW4401 is a part-time four-wheel drive
unit. Torque input in four-wheel drive is undifferentiated.
The range positions are selected by a floor-mounted
gear shift lever. The unit has a gear reduction ratio of
2.69:1.
The BW4401 has a three-piece aluminum case with
provisions for a power take off (PTO) and uses an elec­
tric synchronizer when shifting into four-wheel drive.
IDENTIFICATION (Figures 1 and 2)
The identification tag is an aluminum tag attached
under the self-tapping extension housing bolts. This tag
provides the transfer case model number, serial number
and the build date. The information on this tag is neces­
48. Shift Lever
58. Front Output Flange
60. Four Wheel Drive
Indicator Switch
78. Vent
100. Main Shaft Oil Seal
GENERAL DESCRIPTION
Figure 1— BW4401 Rear Case Half
100
sary for servicing information. If the tag is removed or
becomes dislodged during service operations, be sure
to keep the identification tag with the unit.
POWER FLOW
In all drive range positions input torque is transmitted
to the transfer case gear train through the transfer case
input gear (figure 3).
In 2HI range, torque flows from the input gear to the
range shift hub and mainshaft. Torque flow continues
through the slip/fixed yoke which is splined to the main­
shaft, and finally to the rear propeller shaft and axle. In
2HI range, the mode synchronizer remains in the neu­
tral position. 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 4HI position, the mode