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

6. If the reading is too low, remove the adjusting nut
locks, and loosen the left nut one slot. Then tighten
the right nut one slot.
• The side bearing preload will not change as
long as the adjusting nut is tightened an equal
amount to the nut which was loosened.
GEAR TOOTH
PATTERN CHECK
Checking the ring gear to pinion tooth pattern is done
only after setting up the axle according to the methods
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 used only 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 18).
2. Apply gear marking compound (GM P/N 1052351)
or equivalent sparingly to all ring gear teeth using a
medium-stiff brush. When properly used, the area
of pinion tooth contact will be visible when a hand
load is applied.
3. Tighten the bearing cap bolts to the specified
torque.
4. Expand the brake shoes until a torque of 54 to 68
N-m (40 to 50 lbs. ft.) is required to turn the pinion.
• A test made without loading the gears will not
give a satisfactory pattern. Turn the pinion
flange with a wrench so the ring gear rotates
one full revolution, then reverse the rotation so
the ring gear rotates one revolution in the oppo­
site direction.
5. Observe the pattern on the ring gear teeth and
compare this with figure 19.
ADJUSTM ENTS AFFECTING
TOOTH CONTACT
Two adjustments can be made that affect tooth con­
tact pattern: backlash and pinion depth. The effects of
bearing preloads are not readily apparent on hand load­
ed tooth contact pattern tests; however, these adjust­
ments should be within specifications before proceeding
with backlash and drive pinion adjustments.
Pinion depth is adjusted by increasing or decreasing
the distance between the pinion head and the centerline
of the ring gear. The shim is used in the axle to com­
pensate for manufacturing tolerances. Decreasing the
distance will move the pinion closer to the centerline 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 and/or adjusting nuts. These move the
case and ring gear 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 (Figure 1)
1. Drive axles.
2. Gasket (23) and cover (24) to the housing.
NOTICE: Refer to "Notice" on page 4B4-1.
3. Cover bolts (25).
• Cover bolts (25) to 27 N-m (20 lbs. ft.
4. Lubricant to the axle.