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REAR DRIVELINE MODULE
REAR DRIVELINE MODULE (Continued)
SPECIFICATIONS - REAR DRIVELINE MODULE
DESCRIPTION
Bolt, Driveline Module-to-
Body
Bolt, Overrunning Clutch
Housing-to-Differential
Nut, Input Flange
Plug, Differential Drain/Fill
Plug, Overrunning Clutch
Housing Drain/Fill
Vent, Differential/
Overrunning Clutch
Housing
SPECIAL TOOLS
Tool 6958
Tool 8493
Tool 8802
TORQUE SPECIFICATIONS
N·m
54
60
135
35
30
12
BI-DIRECTIONAL
OVERRUNNING CLUTCH
DESCRIPTION
The bi-directional overrunning clutch (BOC) (Fig.
41) works as a mechanical disconnect between the
front and rear axles, preventing torque from being
transferred from the rear axle to the front. The BOC
is a simply an overrunning clutch which works in
both clockwise and counter-clockwise rotations. This
means that when the output (the rear axle) is rotat-
ing faster in one direction than the input (front axle),
there is no torque transmission. But when the input
speed is equal to the output speed, the unit becomes
locked. The BOC provides significant benefits regard-
ing braking stability, handling, and driveline durabil-
ity. Disconnecting the front and the rear driveline
during braking helps to maintain the braking stabil-
ity of an AWD vehicle. In an ABS/braking event, the
locking of the rear wheels must be avoided for stabil-
ity reasons. Therefore brake systems are designed to
lock the front wheels first. Any torque transfer from
the rear axle to the front axle disturbs the ABS/brak-
ing system and causes potential instabilities on a
slippery surface. The BOC de-couples the rear driv-
eline as soon the rear wheels begin to spin faster
than the front wheels (front wheels locked) in order
to provide increased braking stability. Furthermore
the BOC also reduces the likelihood of throttle off
over-steer during cornering. In a throttle off maneu-
ver, the BOC once again de-couples the rear driveline
forcing all the engine brake torque to the front
wheels. This eliminates the chance of lateral slip on
the rear axle and increases it on the front. The vehi-
cle will therefore tend to understeer, a situation
Ft. Lbs.
40
44
100
26
22
—
CS
In. Lbs.
—
—
—
—
—
110
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