Jeep Wrangler 1997 Manual page 208

3- 82 DIFFERENTIAL AND DRIVELINE
GENERAL INFORMATION (Continued)
API GL 5 quality specifications . Mopar Hypoid Gear
Lubricant conforms to both of these specifications .
" Lubricant is a thermally stable SAE 80W-90
gear lubricant.
" Lubricant for axle with Trailer Tow is SAE
75W-140 SYNTHETIC gear lubricant.
" Trac-Lok differentials add 4 oz. of friction mod-
ifier .
" Lubricant capacity is 1.66 L (3 .50 pts.) .
CAUTION : If axle is submerged in water, lubricant
must be replaced immediately to avoid possible
premature axle failure .
DESCRIPTION AND OPERATION
AXLES
TJ vehicles with 4.0 L engine is equipped with a
Model 216 RBI rear axle.
The Model 216 RBI axle housing has a cast iron
center section. Two steel axle shaft tubes are pressed
and welded into the center section.
It is not necessary to remove the axle from the
vehicle for service . A removable differential cover is
provided for routine vehicle service.
IDENTIFICATION
Model 216 RBI axle has the assembly part number
and gear ratio listed on a tag. The tag is attached to
the left side of the housing cover. Build date identifi-
cation codes on axles are stamped on the axle shaft
tube cover side.
STANDARD DIFFERENTIAL OPERATION
The differential gear system divides the torque
between the axle shafts . It allows the axle shafts to
rotate at different speeds when turning corners.
Each differential side gear is splined to an axle
shaft. The pinion gears are mounted on a pinion
mate shaft and are free to rotate on the shaft. The
pinion gear is fitted in a bore in the differential case
and is positioned at a right angle to the axle shafts .
In operation, power flow occurs as follows :
" The pinion gear rotates the ring gear
" The ring gear (bolted to the differential case)
rotates the case
" The differential pinion gears (mounted on the
pinion mate shaft in the case) rotate the side gears
" The side gears (splined to the axle shafts) rotate
the shafts
During straight- ahead driving, the differential
pinion gears do not rotate on the pinion mate shaft.
This occurs because input torque applied to the gears
is divided and distributed equally between the two
side gears. As a result, the pinion gears revolve with
the pinion mate shaft but do not rotate around it
(Fig . 2).
IN STRAIGHT AHEAD DRIVING
EACH WHEEL ROTATES AT 100%
OF CASE SPEED
PINION GEARS ROTATE
ON PINION SHAFT
TJ
PINION GEARS ROTATE
WITH CASE J9303-13
Fig. 2 Differential Operation-Straight Ahead Driving
When turning corners, the outside wheel must
travel a greater distance than the inside wheel in
order to complete a turn . The difference must be
compensated for, to prevent the tires from scuffing
and skidding through turns. To accomplish this, the
differential allows the axle shafts to turn at unequal
speeds (Fig. 3). In this instance, the input torque
applied to the pinion gears is not divided equally.
The pinion gears now rotate around the pinion mate
shaft in opposite directions . This allows the side gear
and axle shaft attached to the outside wheel to rotate
at a faster speed.
OUTER WHEEL 100% DIFFERENTIAL INNER WHEEL
110% CASE SPEED CASE SPEED 90% CASE SPEED
Fig. 3 Differential Operation-On Turns
J9303-14
TRAC-LOK OPERATION
In a conventional differential, the torque applied to
the ring gear is transmitted to the axle shafts
through the differential gears. During normal opera-
tion, the torque transmitted to each wheel is equal at
all times. However, if one wheel spins, the opposite