Jeep 1996 Grand Cherokee Service Manual - page 122
Trac-lok operation is normal. In extreme cases of dif-
ferences of traction, the wheel with the least traction
may spin.
DIAGNOSIS AND TESTING
GENERAL INFORMATION
The Model 44 housing has an aluminum center
casting (differential housing) with axle shaft tubes
extending from either side. The tubes are pressed
into the differential housing 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 loads are supported by the axle
shaft and bearings. The axle shafts are retained by
C–clips in the differential side gears.
The cover provides a means for servicing the differ-
ential without removing the axle.
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 spacer shims
positioned between the side bearing race and the
housing. Pinion bearing preload is set and main-
tained by the use of a collapsible spacer.
GEAR AND BEARING NOISE
GEAR NOISE
Axle gear noise can be caused by insufficient lubri-
cant. Incorrect backlash, tooth contact, or worn/dam-
aged gears can cause noise.
Gear noise usually happens at a specific speed
range. The range is 30 to 40 mph, or above 50 mph.
The noise can also occur during a specific type of
driving condition. These conditions are acceleration,
deceleration, coast, or constant load.
When road testing, accelerate the vehicle to the
speed range where the noise is the greatest. Shift
out–of–gear and coast through the peak–noise range.
If the noise stops or changes greatly, check for insuf-
ficient lubricant. Incorrect ring gear backlash, or
gear damage can cause noise changes.
Differential side and pinion gears can be checked
by turning the vehicle. They usually do not cause
noise in straight–ahead driving. The side gears are
loaded during vehicle turns. If noise does occur dur-
ing vehicle turns, the side or pinion gears could be
worn or damaged. A worn pinion gear mate shaft can
also cause a snapping or a knocking noise.
BEARING NOISE
The axle shaft, differential and pinion gear bear-
ings can all produce noise when worn or damaged.
Bearing noise can be either a whining, or a growling
sound.
Pinion gear bearings have a constant–pitch noise.
This noise changes only with vehicle speed. Pinion
bearing noise will be higher because it rotates at a
faster rate. Drive the vehicle and load the differen-
tial. If bearing noise occurs the pinion rear bearing is
the source of the noise. If the bearing noise is heard
during a coast, front bearing is the source.
Worn, damaged differential bearings usually pro-
duce a low pitch noise. Differential bearing noise is
similar to pinion bearing. The pitch of differential
bearing noise is also constant and varies only with
vehicle speed.
Axle shaft bearings produce noise and vibration
when worn or damaged. The noise generally changes
when the bearings are loaded. Road test the vehicle.
Turn the vehicle sharply to the left and to the right.
This will load the bearings and change the noise
level. Where axle bearing damage is slight, the noise
is usually not noticeable at speeds above 30 mph.
Fig. 3 Trac-lok Limited Slip Differential Operation
ZJ
DIFFERENTIAL AND DRIVELINE
3 - 77
DESCRIPTION AND OPERATION (Continued)