GMC 1990 Light Truck Repair Manual page 182

101 2
4B4-8 / -INCH RING GEAR
T ighten
• The ring gear bolts in sequence to 163 N-m
(120 ft. lbs.).
7. Differential side bearings (18) using J 24429 and
J 8092 (figure 17).
• Place J 8107 into the differential on the side
opposite of bearing installation to protect the
differential case.
• Drive the bearing onto the case using J 24429
and J 8092.
8. Differential case (34) to the axle housing. Refer to
"Side Bearing Preload Adjustment" in this section.
SIDE BEARING PRELOAD ADJUSTMENT
• The differential side bearing preload is adjusted by
two adjusting nuts in the differential bearing bore.
The bore and the bearing cap provide the mating
threads for the bearing nut.
• The differential must be initially preloaded in order
to determine the backlash of the gear set. After the
backlash has been set, the final bearing preload is
set.
-►+ Install or C onnect (Figure 18)
Tool Required:
J 24429 Side Bearing Backlash Spanner
Wrench
1. The bearing cups (20) to the differential bearings in
their original locations.
2. Differential assembly to the axle housing.
3. Adjusting nuts (19).
4. Bearing caps (20) and bolts (28) in their original
positions.
• Assembly the caps loosely.
• Loosen the right side adjusting nut, and tighten the
left side nut using J 24429 until the ring gear
contacts the drive pinion. Do not force the gears into
contact. This is the zero lash point.
• Back off the left adjusting nut approximately two
slots to obtain the initial backlash adjustment.
5. Adjusting nut lock (21) and lock bolt (22) to the left
nut.
• Do not tighten.
Tighten the right adjusting nut firmly to force the
case into solid contact with the left adjusting nut.
Rotate the pinion several times to seat the bearings.
Loosen the right adjusting nut until it is free from its
bearing.
Tighten the right adjusting nut until it just contacts
the bearing. Additionally tighten the nut two slots for
used bearings, or three slots if new bearings are
installed.
Adjusting nut lock (21) and lock bolt (22) to the left
nut.
• Do not tighten.
• The bearing cap bolts (28) to 183 N-m (135 ft.
lbs.).
• Measure the ring gear to pinion backlash. Refer to
" Backlash Adjustment" in this section.
BACKLASH ADJUSTMENT
1. Install a dial indicator to the case using a magnetic
base (figure 19).
2. 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 perpendicular to the
tooth angle.
3. Check and record the backlash at three or four
points around the ring gear.
• The pinion must be held stationary when
checking backlash.
• The backlash should be the same at each
point within 0.05 mm (0.002-inch). If the
backlash varies more than 0.05 (0.002-inch),
check for burrs, a distorted case flange,
uneven bolting conditions, or foreign matter
between the case and the ring gear.
4. The backlash at the minimum lash point measured
should be between
(0.005-0.008-inch). The maximum acceptable
reading is 0.076-0.203 mm (0.003-0.008-inch).
0.125-0.200 mm