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TJ
ADJUSTMENTS (Continued)
(23) Record dial indicator reading.
(24) Subtract 0.002 in. (0.05 mm) from the dial
indicator reading to compensate for backlash between
ring and pinion gears. This total is the thickness of
shim required to achieve proper backlash.
(25) Subtract the backlash shim thickness from
the total preload shim thickness. The remainder is
the shim thickness required on the pinion side of the
axle housing.
(26) Rotate dial indicator out of the way on guide
stud.
(27) Remove differential case and dummy bearings
from axle housing.
(28) Install new side bearing cones and cups on
differential case.
(29) Install spreader W-129-B, utilizing some com-
ponents of Adapter Set 6987, on axle housing and
spread axle opening enough to receive differential
case.
(30) Place side bearing shims in axle housing
against axle tubes.
(31) Install differential case in axle housing.
(32) Rotate the differential case several times to
seat the side bearings.
(33) Position the indicator plunger against a ring
gear tooth (Fig. 73).
(34) Push and hold ring gear upward while not
allowing the pinion gear to rotate.
(35) Zero dial indicator face to pointer.
(36) 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 differential housing to the
other (Fig. 74).
(37) 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 the
Gear Contact Pattern Analysis procedure.
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.
DIFFERENTIAL AND DRIVELINE
Fig. 73 Ring Gear Backlash Measurement
Fig. 74 Backlash Shim Adjustment
(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
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. 75) and adjust pinion depth and gear backlash
as necessary.
3 - 77
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