housing has an aluminum center casting (differential
housing) with axle shaft tubes extending from either
side. The tubes are pressed into the differential hous-
ing to form a one–piece axle housing.

The integral type housing, hypoid gear design has

the center-line of the pinion set below the center-line
of the ring gear.

The axle has a vent hose to relieve internal pres-

sure caused by lubricant vaporization and internal
expansion.

The axles are equipped with semi–floating axle

shafts, meaning that vehicle load is supported by the
axle shaft and bearings. The axle shafts are retained
by bearing retainer plates on the axles which are
bolted to flanges at the outboard end of the axle
tubes.

The cover provides a means for servicing the differ-

ential without removing the axle.

For vehicles equipped with ABS brakes, the axles

have a tone ring pressed onto the axle shaft. Use
care when removing axle shafts to ensure that the
tone wheel or the wheel speed sensor are not dam-
aged.

The 226 RBA axle has the assembly part number

and gear ratio listed on a tag. The tag is attached to
the differential housing by a cover bolt. Build date
identification codes are stamped on the cover side of
an axle shaft tube.

The differential case is a one-piece design. The dif-

ferential pinion mate shaft is retained with a
threaded pin. Differential bearing preload and ring
gear backlash is adjusted by the use of selective
spacer shims. Pinion bearing preload is set and
maintained by the use of a collapsible spacer (Fig. 1).

Axles equipped with a Trac-Lok

y differential are

optional. A Trac-Lok differential has a one-piece dif-
ferential case, and the same internal components as
a standard differential, plus two clutch disc packs.

Axles equipped with a Vari-Lok

y differential are

optional. A Vari-Lok

y differential has a one-piece dif-

ferential case which contains the gerotor pump
assembly and the clutch mechinism. The Vari-Lok

unit is serviced only as an assembly.

226 RBA AXLE

3 - 95

OPERATION

The axle receives power from the transmission/

transfer case through the rear propeller shaft. The
rear propeller shaft is connected to the pinion gear
which rotates the differential through the gear mesh
with the ring gear bolted to the differential case. The
engine power is transmitted to the axle shafts
through the pinion mate and side gears. The side
gears are splined to the axle shafts.

LUBRICANT

DESCRIPTION

A multi–purpose, hypoid gear lubricant which con-

forms to the following specifications should be used.
Mopar

t Hypoid Gear Lubricant conforms to all of

these specifications.

• The lubricant should have MIL–L–2105C and

API GL 5 quality specifications.

• Lubricant is a thermally stable SAE 80W–90

gear lubricant.

• Lubricant for axles intended for heavy-duty or

trailer tow use is SAE 75W–140 SYNTHETIC gear
lubricant.

Trac-lok

y differentials require the addition of

0.11L (0.25 pts.) of friction modifier to the axle lubri-
cant. The 226 RBA axle lubricant capacity is 2.24 L
(4.75 pts.) total, including the friction modifier if nec-
essary.

Vari-lok

y equipped axles require the addition of

0.12L (0.25 pts.) of friction modifier to the axle lubri-
cant. The 226 RBA axle lubricant capacity for axles
equipped with a Vari-lok

y differential is 2.25 L (4.75

pts.) total, including the friction modifier.

CAUTION: If axle is submerged in water, lubricant
must be replaced immediately to avoid possible
premature axle failure.

STANDARD DIFFERENTIAL

DESCRIPTION

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.

OPERATION

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 pin-

ion 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).

Fig. 1 Shim Locations

1 – PINION GEAR DEPTH SHIM
2 – DIFFERENTIAL BEARING SHIM-PINION GEAR SIDE
3 – RING GEAR
4 – DIFFERENTIAL BEARING SHIM-RING GEAR SIDE
5 – COLLAPSIBLE SPACER

Fig. 2 Differential Operation—Straight Ahead Driving

1 – IN STRAIGHT AHEAD DRIVING EACH WHEEL ROTATES AT

100% OF CASE SPEED

2 – PINION GEAR
3 – SIDE GEAR
4 – PINION GEARS ROTATE WITH CASE

3 - 96

226 RBA AXLE

DESCRIPTION AND OPERATION (Continued)

When turning corners, the outside wheel must

travel a greater distance than the inside wheel 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.

VARI-LOK

Y DIFFERENTIAL

DESCRIPTION

Vari-lok

y differentials are a speed-sensing torque

transfer differential. Similiar to Trac-lok

y differen-

tials, these differentials transfer torque to the wheel
with the greater traction. Unlike typical differential
systems, torque transfer is proportional to wheel
speed

difference

rather

than

torque

difference.

Response

can

tuned

driving

conditions,

enabling use of this system in the front axle. Both
front and rear Vari-lok

y axle torque transfer charac-

teristics are tuned to provide smooth operation.
Except for the ability to maintain headway under
low-traction conditions, operation is barely noticable
to the driver.

OPERATION

In a standard differential, if one wheel spins, the

opposite wheel will generate only as much torque as
the spinning wheel.

A gerotor pump and clutch pack are used to pro-

vide the torque transfer capability. One axle shaft is
splined to the gerotor pump and one of the differen-
tial side gears, which provides the input to the pump.
As a wheel begins to lose traction, the speed differ-
ential is transmitted from one side of the differential
to the other through the side gears. The motion of
one side gear relative to the other turns the inner
rotor of the pump. Since the outer rotor of the pump
is grounded to the differential case, the inner and
outer rotors are now moving relative to each other
and therefore creates pressure in the pump. The tun-
ing of the front and rear axle orifices and valves
inside the gerotor pump is unique and each system
includes a torque-limiting pressure relief valve to
protect the clutch pack, which also facilitates vehicle
control under extreme side-to-side traction varia-
tions. The resulting pressure is applied to the clutch
pack and the transfer of torque is completed.

Under conditions in which opposite wheels are on

surfaces with widely different friction characteristics,
Vari-lok

y delivers far more torque to the wheel on

the higher traction surface than do conventional
Trac-lok

y systems. Because conventional Trac-loky

differentials are initially pre-loaded to assure torque
transfer, normal driving (where inner and outer
wheel speeds differ during cornering, etc.) produces
torque transfer during even slight side-to-side speed
variations. Since these devices rely on friction from
this preload to transfer torque, normal use tends to
cause wear that reduces the ability of the differential
to transfer torque over time. By design, the Vari-lok

system is less subject to wear, remaining more con-
sistent over time in its ability to transfer torque. The
coupling assembly is serviced as a unit. From a ser-
vice standpoint the coupling also benefits from using
the same lubricant supply as the ring and pinion
gears.

Fig. 3 Differential Operation—On Turns

1 – PINION GEARS ROTATE ON PINION SHAFT

226 RBA AXLE

3 - 97

DESCRIPTION AND OPERATION (Continued)

Content .. 35 36 37 38 ..