Jeep 1997 Grand Cherokee Service Manual page 102

DIAL CATOR INDI-
3 - 44 DIFFERENTIAL AND DRIVELINE
ADJUSTMENTS (Continued)
(34) Rotate the differential case several times to
seat the side bearings.
(35) Position the indicator plunger against a ring
gear tooth (Fig. 76).
(36) Push and hold ring gear upward while not
allowing the pinion gear to rotate.
(37) Zero dial indicator face to pointer.
(38) Push and hold ring gear downward while not
allowing the pinion gear to rotate. Dial indicator
reading should be between 0.12 mm (0.005 in.) and
0.20 mm (0.008 in.). If backlash is not within specifi-
cations transfer the necessary amount of shim thick-
ness from one side of the axle housing to the other
(Fig. 77).
(39) Verify differential case and ring gear runout
by measuring ring to pinion gear backlash at several
locations around the ring gear. Readings should not
vary more than 0.05 mm (0.002 in.). If readings vary
more than specified, the ring gear or the differential
case is defective.
After the proper backlash is achieved, perform
Gear Contact Pattern Analysis procedure.
Fig. 76 Ring Gear Backlash Measurement
GEAR CONTACT PATTERN ANALYSIS
The ring and pinion gear teeth contact patterns
will show if the pinion gear depth is correct in the
axle housing. It will also show if the ring gear back-
lash has been adjusted correctly. The backlash can be
adjusted within specifications to achieve desired
tooth contact patterns.
(1) Apply a thin coat of hydrated ferric oxide, or
equivalent, to the drive and coast side of the ring
gear teeth.
(2) Wrap, twist, and hold a shop towel around the
pinion yoke to increase the turning resistance of the
pinion gear. This will provide a more distinct contact
pattern.
(3) Using a boxed end wrench on a ring gear bolt,
Rotate the differential case one complete revolution
FOR MORE BACKLASH INCREASE SHIM THIS SIDE FOR LESS BACKLASH
DECREASE INCREASE SHIM THIS DIE SHIM THIS
SIDE FOR MORE BACK- FOR LESS BACKLASH
LASH
Fig. 77 Backlash Shim Adjustment
in both directions while a load is being applied from
shop towel.
The areas on the ring gear teeth with the greatest
degree of contact against the pinion gear teeth will
squeegee the compound to the areas with the least
amount of contact. Note and compare patterns on the
ring gear teeth to Gear Tooth Contact Patterns chart
(Fig. 78) and adjust pinion depth and gear backlash
as necessary.
SPECIFICATIONS
181 FBI AXLE
Axle Type . . . . . . . . . . . . . . . . . . . . . . . . . . . Hypoid
Lubricant . . . . . . . . SAE Thermally Stable 80W–90
Lube Capacity . . . . . . . . . . . . . . . . . . 1.2 L (2.5 pts.)
Axle Ratio . . . . . . . . . . . . . . . . 3.07, 3.55, 3.73, 4.10
Differential Side Gear Clearance . . . . 0.12–0.20 mm
Ring Gear Diameter . . . . . . . . . 18.09 cm (7.125 in.)
Backlash . . . . . . . . . . . 0–0.15 mm (0.005–0.008 in.)
Pinion Std. Depth . . . . . . . . . . . 92.1 mm (3.625 in.)
Pinion Bearing Rotating Torque . . . . . . . . . . . . . . . .
Original Bearings . . . . . . . . 1–2 N·m (10–20 in. lbs.)
New Bearings . . . . . . . . . 1.5–4 N·m (15–35 in. lbs.)
FOR MORE BACKLASH
DECREASE SHIM THIS
SIDE FOR LESS BACK-
LASH
ZG
(0.005–0.008 in.)