GMC T Series 1994 Repair Manual page 905

BORG-WARNER 4470 TRANSFER CASE
N O T IC E : W h e n f a s t e n e r s a r e r e m o v e d , a lw a y s r e in s t a ll th e m a t th e s a m e lo c a t io n f r o m w h ic h th e y w e r e
r e m o v e d . I f a f a s t e n e r n e e d s to b e re p la c e d , u s e th e c o r r e c t p a r t n u m b e r f a s t e n e r f o r t h a t a p p lic a t io n . I f
th e c o r r e c t p a r t n u m b e r f a s t e n e r is n o t a v a ila b le , a f a s t e n e r o f e q u a l s iz e a n d s t r e n g t h ( o r s t r o n g e r ) m a y
b e u s e d . F a s t e n e r s t h a t a r e n o t r e u s e d , a n d t h o s e r e q u ir in g t h r e a d lo c k in g c o m p o u n d w ill b e c a lle d o u t.
T h e c o r r e c t t o r q u e v a lu e m u s t b e u s e d w h e n in s t a llin g fa s t e n e r s t h a t r e q u ir e it. I f th e a b o v e c o n d it io n s
a r e n o t fo llo w e d , p a r t s o r s y s t e m d a m a g e c o u ld r e s u lt.
SUBJECT
General D escription..................................................................................................................................................... 7D6- 1
BW4470 Transfer Case.............................................................................................................................................7D6- 1
Identification...........................................................................................................................................................7D6- 1
Power F lo w ............................................................................................................................................................. 7D6- 1
Disassem bly....................................................................................................................................................................7D6- 2
External Components..............................................................................................................................................,7D 6- 2
Internal Com ponents................................................................................................................................................7D6- 3
Synchronizer Hub Assem bly..................................................................................................................................7D6- 3
Oil Pump Assem bly.................................................................................................................................................. 7D6- 3
Cleaning and Inspection.............................................................................................................................................7D6-11
Assem bly.......................................................................................................................................................................... 7D6-11
Oil Pump Assem bly.................................................................................................................................................. 7D6-11
Synchronizer A ssem bly.......................................................................................................................................... 7D6-12
Internal Com ponents................................................................................................................................................7D6-12
External Components...............................................................................................................................................7D6-13
S pecifications................................................................................................................................................................ 7D6-14
Fastener Tightening Specificaticns..................................................................................................................... 7D6-14
Lubrication Specifications...................................................................................................................................... 7D6-14
Special T o o ls ................................................................................................................................................................. 7D6-14
BW 4470 TRANSFER CASE
The Borg-Warner 4470 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 BW4470 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 BW4470 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
The identification tag is an aluminum tag attached
under the self-tapping extension housing bolts. This tag
provides the transfer case model number, serial num­
ber, and the build date. The information on this tag is
necessary for servicing inform ation. If the tag is
removed or becomes dislodged during service opera­
SECTION 7D6
CONTENTS
GENERAL DESCRIPTION
tions, be sure to keep the identification tag with the unit.
Refer to figures 1 and 2.
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 the 2HI range, torque flows from the input gear to
the range shift hub and mainshaft. Torque flow contin­
ues through the slip/fixed yoke which is splined to the
mainshaft, and finally to the rear propeller shaft and
axle. In the 2HI range, the mode synchronizer remains
in the neutral position. As a result, torque is not trans­
ferred to the driven sprocket.
In the 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
synchronizer sleeve is shifted into engagement with the
clutch hub teeth on the mainshaft. This locks the drive
sprocket to the main shaft through the synchronizer
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