Gear Tooth Pattern Check; Adjustm Ents Affecting Tooth Contact; Final Assembly - GMC T Series 1994 Repair Manual

4. To adjust the backlash, the differential case must
be removed from the housing, the differential bear­
ings removed, and the proper number of shims
moved from one side to the other.
5. Make the final gear pattern check.
GEAR TOOTH
PATTERN CHECK
Checking the ring gear to pinion tooth pattern is done
only after setting up the axle according to the methods
described in this section. The pattern check is NEVER
used as an initial check or instead of checking pinion
depth and backlash adjustments. This check is only
used to verify the correct adjustment of the gear set
after setup.
1. Wipe all oil out of the housing and carefully clean
each tooth of the ring gear (figure 29).
2. Apply gear-marking compound (GM P/N 1052351)
or equivalent to all ring gear teeth using a medi-
um-stiff brush. When properly used, the area of
pinion tooth contact will be visible when a hand
load is applied.
NOTICE: Refer to "Notice" on page 4B5-1.
3. Tighten the bearing cap bolts to 115 N.m
(85 lbs. ft.).
4. Load the differential until a torque of 62 N-m
(45 lbs. ft.) is required to rotate the pinion.
A load may be placed on the differential by pry­
ing between the differential case and the axle
housing with a suitable prying device while rotating
the pinion and observing the torque required to
rotate it.
A test made without loading the gears will not
give a satisfactory pattern. Turn the pinion flange
with a wrench until the ring gear rotates one full
revolution, then reverse the rotation until the ring
gear rotates one revolution in the opposite direc­
tion.
5. Observe the pattern on the ring gear teeth and
compare this with figure 30.
ADJUSTM ENTS AFFECTING
TOOTH CONTACT
Two adjustments can be made that affect tooth con­
tact pattern: backlash and drive pinion depth. The
effects of bearing preloads are not readily apparent on
hand loaded tooth contact pattern tests; however, these
adjustments should be within specifications before pro­
ceeding with backlash and drive pinion adjustments.
The position of the drive pinion is adjusted by
increasing or decreasing the distance between the pin­
ion head and the centerline of the ring gear. Decreasing
the distance will move the pinion closer to the center-
line of the ring gear. Increasing the distance will move
the pinion farther away from the centerline of the ring
gear.
Backlash is adjusted by means of the side bearing
adjusting shims that move the case and ring gear
assembly closer to, or farther from, the drive pinion.
(The adjusting shims are also used to set side bearing
preload).
If the thickness of the right shim is increased (along
with decreasing the left shim thickness), backlash will
increase.
If the thickness of the left shim is increased (along
with decreasing the right shim thickness), backlash will
decrease.

FINAL ASSEMBLY

-► <- Install or Connect
1. RTV to the axle cover.
2. Axle cover (14) to the housing.
NOTICE: Refer to "Notice" on page 4B5-1.
Tighten
&
• Cover bolts (17) to 47 N-m (35 lbs. ft.).
3. Lubricant to the axle.