Backlash Adjustment - GMC 1989 Light Duty Truck Repair Manual

4C1-10 V -INCH RING GEAR
8 2
• Support the case to keep it from falling into the
axle housing.
2. Install the strap from J 22779 on the left bearing with
the cap bolts. Tighten the bolts snuggly.
3. Push the ring gear towards the pinion.
• Engage the ring gear with the pinion tightly to
obtain a backlash of .000 mm to 0.0254 mm
(0.000 to 0.001-inch).
4. Insert J 22779 between the axle housing and the left
bearing cup (figure 20).
5. Move the tool back and forth in the bore while
turning the adjusting nut to the right until a noticable
drag is produced (figure 21).
• Tighten the lock bolts on the side of the tool.
• Leave the tool in place.
6. Install a service spacer (9) and a service shim (9)
between the right bearing cup and the axle housing.
7. Determine bearing preload by inserting progresively
larger feeler gage sizes between the carrier and the
service shim.
Figure 21— Measuring Side Bearing Shim
Requirements
• Push the feeler gage downward so that it
contacts the shim at the top and bottom, and
then contacts the axle housing.
• The point just before additional drag begins is
the correct feeler gage thickness. This is the
zero setting without preload.
8. Remove the strap, J 22779, the service spacer,
service shim, feeler gage, and differential case from
the axle housing.
9. M e a s u re J 22779 in th re e
micrometer. Average the readings (figure 22).
10. Add the dimensions of the service spacer, service
shim, and the feeler gage.
11. For an initial backlash setting, move the ring gear
away from the pinion by subtracting 0.010-inch from
the ring gear side shim pack and adding 0.010-inch
to the shim pack on the opposite side.
12. To obtain the proper preload on the side bearings
add 0.10 mm (0.004-inch) to the measurement of
each shim pack.
13. In s ta ll th e d iffe r e n tia l. R e fe r to " B a c k la s h
Adjustm ent" in this section.

BACKLASH ADJUSTMENT

1. Install the differential case, bearing cups, spacers,
and shims as determined from the " Side Bearing
Preload Adjustm ent" earlier in this section (figure
23).
• Tap the final shim into position, using a soft
faced hammer.
2. Rotate the case several times to seat the bearings.
3. Install a dial indicator to the case using a magnetic
base.
4. Place the indicator stem at the heel end of a tooth.
• Set the dial indicator so that the stem is in line
with the gear rotation and at a right angle to
the tooth angle (figure 24).
5. Install the differential caps (10) and bolts (18).
p la c e s u s in g a