Pinion Depth Adjustment; Pinion Installation; Differential Assembly Installation; Adjusting Backlash - GMC 1989 Light Duty Truck Repair Manual

PINION DEPTH ADJUSTMENT

Tools Required:
J 33838 Pinion Depth Setting Gage
J 29763 Dial Indicator
1. Refer to figure 1.
2. Pinion depth is adjusted by selecting a shim (38) of
the proper thickness.
3. Lubricate the inner and outer pinion bearings
liberally with axle lubricant.
4. Hold the pinion bearings in position and install
J 33838 and J 29763 (figu re 19). Set the dial
indicator at ZERO, then position it in J 33838. Push
the dial indicator downward until the needle rotates
approximately three turns to the right.
5. Tighten the dial indicator in this position.
6. Set the button of J 33838 on the differential bearing
bore (figure 19).
7. Rotate the tool slowly back and forth unitl the dial
indicator reads the lowest point of the bore. Set the
dial indicator to ZERO. Repeat the rocking action of
the tool to verify the ZERO setting.
8. After the ZERO setting is obtained and verified,
move the tool button out of the differential side
bearing bore (figure 19). Record the dial indicator
reading.
9. The dial indicator reading is equal to the required
shim size. Exam ple: If the dial indicator reads
0.84 mm in step 8, a 0.84 mm shim is required.
Available shim sizes are listed in " Specifications."
10. Remove the tools and bearing cones.

PINION INSTALLATION

"► 4- Install or C onnect (Figure 1, 2, 10, 20 and 21)
Tools Required:
J 33785 Bearing Installer
J 8614-01 Pinion Flange Remover
J 33792 Seal Installer
1. Shim (38) to the pinion gear (37).
• The shim must be of the proper size, as
selected previously.
2. Bearing (39) onto the pinion gear (37) using J 33785
(figure 20).
3. New spacer (40) onto the pinion gear (37).
4. Bearing (41) into the case.
5. Seal (42) into the case using J 33782 (figure 21).
6. Pinion gear, with bearing and spacer, to the case.
7. Deflector (43), flange (44), washer (45) and nut (46).
• Apply PST sealant (GM part number 1052080
or equivalent) to the pinion gear threads and
on both sides of the washer.
• Tighten nut (46) until no end play is detectable
while holding the flange (44) with J 8614-01
(figue 10).
• No further tightening should be attempted until
bearing preload has been checked.
M easure
Pinion bearing preload. Use an inch pourd torque
wrench (figure 22). The correct preload is 1.7-2.8
N-m (15-25 in. lbs.).
T TRUCK FRONT AXLE 4C3-9
1. Rotate the pinion with the torque w rench and
observe the reading.
2. If the pre lo a d to rq u e is b elow s p e c ific a tio n s ,
c o n tin u e to rq u in g
in c re m e n ts . C h e c k th e
tightening. Each tightening increases the bearing
preload by several inch pounds. If the bearing
preload is exceeded, the pinion will have to be
removed, and a new collapsible spacer installed.
3. Once the preload has been obtained rotate the
pinion several times to make sure that the bearings
have seated. Recheck the preload, and adjust if
necessary.
DIFFERENTIAL ASSEMBLY
INSTALLATION
■H" Install or C onnect (Figures 1, 2, 23, 24 and 25)
Tools Required:
J 33788 Bearing Installer
J 23423-A Bearing Cup Installer
J 33792 Side Bearing Adjuster Wrench
Bearings (30) into the sleeves (32) using J 33788
(figure 23).
2 Sleeves (32) into the carrier case (29). Thread in all
.
the way.
3. Side bearing cups (33) into the carrier case (29)
using J 23423-A.
Differential assembly to the carrier case.
• Place the differential case assembly (35) into
the carrier case half which contains the pinion
gear.
• Turn th e le ft s le e v e (32) in to w a rd th e
differential case using J 33792 until backlash
is felt between the ring and pinion gear.
Carrier case halves (29). Do not use any sealer at
this time.
• If the carrier halves do not make complete
contact, back out the right hand adjusting
sleeve (32). Use J 33792 (figure 24).
Four bolts (28) (figure 25).
• Bolts (28) to 50N N-m (37 ft. lbs.).

ADJUSTING BACKLASH

Tools Required:
J 33792 Side Bearing Adjuster Wrench
J 34047 Dial Indicator Adapter
J 25025-1 Dial Indicator Stand
J 8001-1 Dial Indicator Clamp
1. Refer to figures 1 and 2.
2. Tiguten the right sleeve (32) to 140 N-m (100 ft. lbs.).
Use J 33792 (figure 24).
3. Tighten the left sleeve (32) to 140 N-m (100 ft. lbs.).
Use J 33792 (figure 24).
4. Mark the location of the adjusting sleeves in relation
to the carrier halves (figure 26), so the notches in
the adjusting sleeves can be counted when turned.
5. Turn the right adjusting sleeve OUT two notches
using J 33792.
th e p in io n n u t in s m a ll
p re lo a d a fte r e a ch