Model 231 Transfer Case; Operating Ranges; Two-Wheel Drive Operation; Four-Wheel Drive Operation - Jeep 1987 Wrangler Workshop Manual

GEARBOXES
MODEL 231 TRANSFER CASE
GENERAL INFORMATION
Transfer Case Application
The Model 231 transfer c a s e is used in 1987
W r a n g l e r / Y J m o d e l s b u i l t a f t e r V I N
2 B C C L 8 1 1 9 H B 5 1 8 2 9 0 and in all 1988 Wran-
gler/YJ models.
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Description
The Model 231 is a part-time transfer c a s e with
a built-in low range reduction gear system. It
has three operating ranges plus a Neutral posi-
tion. The low range system provides a gear
reduction ratio of 2.72:1 for i n c r e a s e d low
speed torque capability.
Operating Ranges
The Model 231 is a part-time unit with three
operating ranges which are: Two-wheel drive
high, four-wheel drive high and four-wheel drive
low. The four-wheel drive ranges are undiffer-
entiated. Differential action between the front/
rear axles does not occur in the four wheel drive
ranges.
Two-Wheel Drive Operation
Two-wheel drive range is for on-road, highway
operation or whenever the vehicle is operated
on a hard road surface.
Two-wheel drive is provided by a disconnect
mechanism in the front axle. A vacuum oper-
ated shift motor on the axle disconnects the
r i g h t - h a n d a x l e s h a f t w h e n 2 H r a n g e is
selected. T h e axle shift motor is controlled by a
vacuum switch that is actuated by the transfer
c a s e shift sector and linkage.
Four-Wheel Drive Operation
Two internal m e c h a n i s m s provide the four-
wheel drive r a n g e s . A v a c u u m shift motor
connects the right-hand axle shaft and a syn-
chronizer assembly engages the transfer c a s e
front output shaft. T h e shift motor is operated
by a vacuum switch mounted on the transfer
c a s e . The switch is actuated by the transfer
c a s e shift linkage.
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