Chevrolet 1973 Overhaul Manual page 29

3-8 FRONT AXLE DIFFERENTIAL
1. Wipe oil out of carrier and carefully clean each
tooth of ring gear.
2. Use gear marking compound and apply this
mixture sparingly to all ring gear teeth using a
medium stiff brush. When properly used, the area
of pinion tooth contact will be visible when hand
load is applied.
3. Tighten bearing cap bolts to 55 lb. ft.
4. Apply a load until a torque of 40-50 lb. ft. is
required to turn the pinion.
NOTE: A test made without loading the
gears will not give a satisfactory pattern.
Turn companion flange with wrench so that
ring gear rotates one full revolution then
reverse rotation so that ring gear rotates one
revolution in opposite direction. Excessive
turning of ring gear is not recommended.
5. Observe pattern on ring gear teeth and compare
with Figure 12.
HIGH FACE CONTACT
IN C R E A S E P IN IO N S H IM
CHEVROLET OVERHAUL MANUAL
Adjustments Affecting Tooth Contact
Two adjustments can be made which will affect tooth
contact pattern. These are backlash and position of drive
pinion in carrier. The effects of bearing preloads are not
readily apparent on hand loaded teeth pattern tests:
however, these adjustments should be within specifica­
tions before proceeding with backlash and drive pinion
adjustments.
NOTE: It may be necessary to adjust both
pinion depth and backlash to obtain the
correct pattern.
The position of the drive pinion is adjusted by
increasing or decreasing the shim thickness between the
pinion head and inner race of rear bearing. The shim is
used in the differential to compensate for manufacturing
tolerances. Increasing shim thickness will move the
pinion closer to centerline of the ring gear. Decreasing
shim thickness will move pinion farther away from
centerline of the ring gear.
Fig. 12—Gear Tooth Contact Pattern
HEEL CONTACT
D E C R E A S E B A C K L A S H