Standard Differential; Differential Ovehaul - Amc/Jeep Axle; Differential Disassembly - Jeep 1979 CJ-5 Technical & Service Manual

AXLES 2F-21
S T A N D A R D D I F F E R E N T I A L
Page Page
Differentia! Operation 2F-21
Differential Overhaul—Axle Models 3 0 4 4 4 0
2F-30
Differential Overhaul—AMC/Jeep Axle 2F-21 General 2F-21
GENERAL
CJ models use the Model 30 front axle and the AMC/
Jeep rear axle which has tapered axle shafts.
Cherokee, Wagoneer, and Truck models use the Model
44F front axle and the Model 44 rear axle with flanged
axle shafts. Truck models rated at 6800 GVWR (3084 kg)
and up use the Model 44F front axle and the Model 60
rear axle with full-floating axle shafts.
Rear axle Models 44 and AMC/Jeep are semi-floating
type axles. Only the Model 60 is a full-floating type unit.
DIFFERENTIAL OPERATION
The differential gear system divides the torque be-
tween the axle shafts and allows them to rotate at dif-
ferent 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, which is bolted
to the differential case, rotates the case. The differential
pinion gears, which are mounted on the pinion mate
shaft, which is fitted in the case, rotate the side gears.
The side gears, which are 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. 2F-29).
When turning corners, the outside wheel must travel
a greater distance than the inside wheel in order to
complete the turn. This difference must be compensated
for in order to prevent the wheels from scuffing and
sliding through the turn. To accomplish this, the differ-
ential becomes effective allowing the axle shafts to ro-
tate at unequal speeds (fig. 2F-30). 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.
I N S T R A I G H T A H E A D D R I V I N G ,
E A C H W H E E L R O T A T E S A T 1 0 0 %
O F C A S E S P E E D
P I N I O N G E A R S R O T A T E
W I T H C A S E
A 5 0 1 1 3
Fig. 2F-29 Differential Operation—Straight Ahead Driving
/
O U T E R W H E E L
1 1 0 % C A S E S P E E D
A X L E
1 0 0 % D I F F E R E N T I A L
C A S E S P E E D
/
I N N E R W H E E L
9 0 % C A S E S P E E D
P I N I O N G E A R S R O T A T E
ON P I N I O N S H A F T
Fig. 2F-30 Differential Operation—On Turns
DIFFERENTIAL OVERHAUL-AMC/JEEP AXLE
Differential Disassembly
N O T E : It is not necessary to remove the rear axle as-
sembly in order to overhaul the differential All differ-
ential service operations can be performed with the axle
mounted in the vehicle.
(1) Remove axle shaft dust caps and retaining nuts.
(2) Raise and support vehicle.
(3) Remove axle housing cover and drain lubricant.