Jeep Wrangler 1997 Manual page 174

3-48
DIFFERENTIAL AND DRIVELINE
DESCRIPTION AND OPERATION (Continued)
through the differential gears. During normal opera-
tion, the torque transmitted to each wheel is equal at
all times . However, if one wheel spins, the opposite
wheel will generate only as much torque as the spin-
ning wheel.
In the Trac-lok differential, part of the ring gear
torque is transmitted through clutch packs. The
clutch packs contain multiple disc. The clutch will
have radial grooves on the plates, and concentric
grooves on the discs or bonded fiber material that is
smooth appearance .
In operation, the Trac-lok clutches are engaged by
two concurrent forces . The first being preload force
exerted through Belleville spring washers contained
in the clutch packs. The second from separating
forces generated by the side gears as torque is
applied through the ring gear (Fig . 4).
Fig. 4 Trac-lok Limited Slip Differential Operation
The Trac-lok design provides differential action
needed for turning corners and for driving straight
ahead. However, when one wheel looses traction, the
clutch packs transfer additional torque to the wheel
having the most traction. Trac-lok differentials resist
wheel spin on bumpy roads and provide more pulling
power when one wheel looses traction . Pulling power
is provided continuously until both wheels loose trac-
tion . If both wheels slip due to unequal traction,
Trac-lok operation is normal. In extreme cases of dif-
GEAR AND BEARING NOISE
TJ
ferences of traction, the wheel with the least traction
may spin .
DIAGNOSIS AND TESTING
DIAGNOSTIC INFORMATION
Axle bearing problem conditions are usually caused
by:
" Insufficient or incorrect lubricant
" Foreign matter/water contamination
" Incorrect bearing preload torque adjustment
Axle gear problem conditions are usually the result
o£
" Insufficient lubrication
" Incorrect or contaminated lubricant
" Overloading (excessive engine torque)
" Incorrect clearance or backlash adjustment
Insufficient lubrication is usually the result of a
housing cover leak . It can also be from worn axle
shaft or pinion gear seals . Check for cracks or porous
areas in the housing or tubes .
Using the wrong lubricant or over filling will cause
overheating and gear failure. Gear tooth cracking
and bearing spalling are indicators of this.
Axle component breakage is most often the result
of:
" Severe overloading
" Insufficient lubricant
" Incorrect lubricant
" Improperly tightened components
Common causes of overloading is from full throttle
acceleration . Overloading happens when towing
heavier than recommended loads. Component break-
age can occur when the wheels are spun excessively .
Insufficient or incorrect lubricants contribute to
breakage through overheating. Loose differential
components can also cause breakage .
Incorrect bearing preload or gear backlash will not
result in component breakage . Mis-adjustment will
produce enough noise to cause service repair before a
failure occurs . If a mis-adjustment condition is not
corrected, component failure wil result .
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