Backlash Adjustment - Chevrolet 1991 Light Duty Truck Repair Manual

401-10 8 1/2-INCH RING GEAR FRONT AXLE
• Production shims are cast iron and are not to be
reused.
• Service spacers are available from 4.32 to 4.37
mm (0.170 to 0.172-inch) thick.
• Service shims are available in kits from 0 040 to
0.070-inch.
• Be sure that the side bearing surfaces are clean
and free of burrs.
1. Place the differential case and the bearing cups
into the axle housing.
• Lubricate the axle bearings with axle lubricant.
• Support the case to keep it from falling into the
axie housing.
2. Install the strap from J 22779 on the left bearing
with the cap bolts. Tighten the bolts snug.
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 19).
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 20).
• 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 hous­
ing.
7. Determine bearing preload by inserting progres­
sively larger feeler gage sizes between the carrier
and the service shim.
• Push the feeler gage downward so that it con­
tacts 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. Measure J 22779 in three places using a microme­
ter. Average the readings (figure 21).
10. Add the dimensions of the service spacer, service
Figure 21— Measuring the Gage Plate Thickness
Figure 23—Checking Ring Gear Backlash
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. Install the differential. Refer to " Backlash Adjust­
ment" in this section.

BACKLASH ADJUSTMENT

1. Install the differential case, bearing cups, spacers,
and shims as determined from the "Side Bearing
Preload Adjustment" earlier in this section (figure
22
).
• 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.