Chevrolet 1980 Light Duty Truck Repair Manual page 81

Fig. 22 B ~ ln sta llin g Rear Bearing
A d ju s tm e n ts A ffe c tin g Tooth C o n tact
T w o adjustments can be m ade w hich w ill affect tooth
contact pattern. These are backlash and position o f drive
pinion in carrier. The effects o f bearing preloads are not
readily apparent on hand loaded teeth pattern tests;
however, these adjustments should be within specifications
before proceeding with
adjustments.
It may be necessary to adjust both pinion
depth and backlash to obtain the correct pattern.
The position o f the drive pinion is adjusted by
increasing or decreasing the shim thickness between the
Fig. 2 3 B ~ ln sta llin g Pinion Oil Seal
backlash and drive pinion
REAR AXLE DIFFERENTIAL
Fig. 24 B ~ M e asu ring R otating Torque
pinion head and inner race o f rear bearing. The shim is used
in the differential to com pensate
tolerances. Increasing shim thickness will m ove the pinion
closer to centerline o f the ring gear. D ecreasing shim
thickness will m ove pinion farther away from centerline o f
the ring gear.
Backlash is adjusted by means o f the side bearing
adjusting shim s w hich m oves the entire case and ring gear
assem bly closer to, or farther from the drive pinion. (The
adjusting shim s are also used to set side bearing preload).
To increase backlash, increase right shim and decrease left
shim an equal am ount. To decrease backlash, decrease right
shim and increase left shim an equal am ount.
The im portant thing to note is that the contact pattern
is centrally located up and dow n on the face o f the ring gear
teeth.
Fig. 25B--Gear Tooth N om enclature
4 B -1 1
for manufacturing
O V E R H A U L M A N U A l