GMC 1976 ZEO 6083 Maintenance Manual page 177

3C- 1 4 FINAL DRIVE
and rotated while applying as much hand pressure as
possible .
NOTE :
Minute scratches and pits that appear on
rollers and races at low mileage are due to the
initial pre-load and bearings having these marks
should not be rejected .
2. Examine the ring gear and drive pinion teeth
for excessive wear and scoring. Any of these condi-
tions will require replacement of the gear set.
3 . Examine housing bores and remove any burrs
that might cause leaks around the OD of the seal .
4. Inspect the differential pinion shaft for unusual
wear; also check the pinion and side gears and thrust
washers.
5. Side beatings must be a tight press fit on the
hub.
6. Diagnosis of a differential failure such as
chipped bearings, loose (lapped-in) bearings, chipped
gears etc. is a warning that some foreign material is
present; therefore, the housing must be thoroughly
cleaned and inspected .
CHECKING PINION DEPTH
1 . Install pinion front outer race as shown in
Figure 35 . Drive race until it bottoms.
2. Lubricate front bearing with final drive lubri-
cant and install into front outer race .
3. Position Tool J-21777-10 on front bearing. In-
stall Tool J-2 f579 on final drive housing and retain
Figure 36-Pre-Loading Pinion Front Bearing
Figure 37-Pinion Depth Gauge Tool Installation
with two bolts. Thread screw J-21777-13 into J-
21579 until tip of screw engages Tool J-21777-10 .
Torque screw J-21777-13 to 20 in . lbs. to pre-load
bearing. (figure 36)
4. Remove dial indicator post from Tool J-21777-
1 and install Discs J-21777-22 as shown in Figure 37 .
Reinstall dial indicator post .
5 . Place the gauging discs in the side bearing
bores and install the side bearing caps . Torque cap
bolts to 75 ft . lbs.
6. Position the dial indicator, J-8001 on the
mounting post of the gauge shaft and with the con-
tact rod OFF the gauging area of J-21777-10 . Set dial
indicator on ZERO, then depress the dial indicator
until the needle rotates 3/4 turn clockwise. Tighten
the dial indicator in this position . RESET DIAL
INDICATOR ON ZERO .
7. Position the gauge shaft assembly in the hous-
ing so that the dial indicator contact rod is directly
in line with the gauging area BUT NOT ON and the
discs seated fully in the side bearing bores.
8. Rotate the gauge shaft assembly until the dial
indicator rod contacts the gauging area of J-21777-
10 . Rotate gauge shaft slowly back and forth until
the dial indicator reads the greatest deflection .
9. At the point of greatest deflection, read the dial
indicator directly for pinion depth.