Jeep 1996 Grand Cherokee Service Manual page 126

ZJ
DIAGNOSIS AND TESTING (Continued)
TRAC-LOK NOISE DIAGNOSIS
If a noise occurs when turning corners, the most
probable cause is incorrect or contaminated lubri-
cant. Before removing the Trac-lok unit for repair,
drain, flush and refill the axle with the specified
lubricant. Refer to Lubricant change in this Group.
A container of Trac-lok Lubricant (friction modifier)
should be added after repair service or a lubricant
change.
Vehicles with a limited slip differential should be
road tested by making 10 to 12 slow figure eight
turns. This maneuver will pump the lubricant
through the clutch discs to eliminate a possible chat-
ter or pop noise complaint.
Refer to Group 0, Lubrication and Maintenance for
additional information.
DIFFERENTIAL TEST
WARNING: WHEN SERVICING VEHICLES WITH A
LIMITED SLIP DIFFERENTIAL DO NOT USE THE
ENGINE TO TURN THE AXLE AND WHEELS. BOTH
REAR WHEELS MUST BE RAISED AND THE VEHI-
CLE SUPPORTED. A LIMITED SLIP AXLE CAN
EXERT ENOUGH FORCE (IF ONE WHEEL IS IN
CONTACT WITH THE SURFACE) TO CAUSE THE
VEHICLE TO MOVE.
The differential can be tested without removing the
differential case by measuring rotating torque. Make
sure brakes are not dragging during this measure-
ment.
(1) Engine off, transmission in neutral, and park-
ing brake off.
(2) Place blocks in front and rear of both front
wheels.
(3) Raise one rear wheel until it is completely off
the ground.
(4) Remove wheel and bolt Special Tool 6790 to
studs.
(5) Use torque wrench on special tool to rotate
wheel and read rotating torque (Fig. 4).
(6) If rotating torque is less than 22 N·m (30 ft.
lbs.) or more than 271 N·m (200 ft. lbs.) on either
wheel the unit should be service.
SERVICE PROCEDURES
LUBRICANT CHANGE
The gear lubricant will drain quicker if the vehicle
has been recently driven.
(1) Raise and support the vehicle.
(2) Remove the lubricant fill hole plug from the
differential housing cover.
(3) Remove the differential housing cover and
drain the lubricant from the housing.
DIFFERENTIAL AND DRIVELINE
Fig. 4 Trac-loc Test
(4) Clean the housing cavity with a flushing oil,
light engine oil or lint free cloth. Do not use water,
steam, kerosene or gasoline for cleaning.
(5) Remove the sealant from the housing and cover
surfaces.
(6) Apply a bead of Mopar Silicone Rubber Sealant
to the housing cover (Fig. 5). Allow the sealant to
cure for a few minutes.
Fig. 5 Typical Housing Cover With Sealant
Install the housing cover within 5 minutes
after applying the sealant.
(7) Install the cover and any identification tag.
Tighten the cover bolts to 41 N·m (30 ft. lbs.) torque.
(8) Refill differential with Mopar Hypoid Gear
Lubricant to bottom of the fill plug hole.
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