Service Manual

7.13
FINAL DRIVE
7
All Wheel Drive Operation
Front Gearcase Engagement: The AWD switch may be
turned on or off while the vehicle is moving. Initially, the
vehicle’s electronic system will not enable the AWD until the
engine RPM is below 3100. Once enabled, AWD will remain
engaged until the rear wheels regain traction and the propshaft
speed matches the front axle speed .
Engage the AWD switch before getting into conditions where
the front wheel drive may be needed. If the rear wheels are
spinning, release the throttle before switching to AWD.
Normal Operation: With the AWD switch off the vehicle
drives only the rear wheels (2 wheel drive). When the AWD
switch is activated it electronically activates the Hilliard Clutch,
and enables the front wheels to provide driving torque when
needed.
4x4 Engagement: When the AWD switch is turned on, a 12
Vdc current charges the hub coil and creates a magnetic field.
This magnetic field attracts an armature plate keyed to a roller
cage that contains 20 rollers. The difference in rpm between the
input shaft (propshaft) and the front axles, forces the rollers into
the external cam of the Hilliard clutch assembly. The rollers are
forced inward to engage themselves to the output hubs that link
directly to both front axles, resulting in True All Wheel Drive.
Roller cage and roller’s rotate inward and grip the output hubs
for AWD engagement.
Mechanical Disengagement: As the front and rear wheels gain
traction, rotating very close to the same speed, the front wheels
“overdrive” the output hubs and the rollers are forced outward,
disengaging the AWD. The vehicle is now back to rear wheel
drive until the rear wheels lose traction again.
CAUTION
Switching to AWD while the rear wheels are
spinning may cause severe drive shaft and
gearcase damage. Always switch to AWD while
the rear wheels have traction or are at rest.
CAUTION
If the rear wheels are spinning, release the
throttle before turning the AWD switch on.
If AWD is engaged while the wheels are
spinning, severe drive shaft and clutch
damage could result.
Roller Cage
& H-springs
Rollers
Output Hubs