GMC 1989 Light Duty Truck Repair Manual page 227

Press the bearings on using a suitable tool.
DIFFERENTIAL INSTALLATION
|-n -| Install or C onnect
1. Bearing cups (33) to the carrier (36).
2. Adjusting nuts (32).
3. Bearing caps (25).
4. Cap bolts (23).
&
Tighten
• Bolts to 176 N-m (130 ft. lbs.).
The bearing cups must have a hand fit in the
bearing bores: If the fit is too tight, rework the bore
with emery cloth, until a hand fit is obtained (figure
23).
Rem ove or D isconnect
Cap bolts (23).
Bearing caps (25).
Adjusting nuts (32).
Bearing cups (33).
0
Install or C onnect
Lubricate all parts with axle lubricant.
Bearing cups (33) onto the bearings.
Differential assembly (36) to the carrier.
Bearing adjusting nuts (32).
• Turn the nuts hand-tight against the bearing
cups.
Bearing caps (25) (figure 24).
• Tap lightly into position.
Cap bolts (23).
&
Tighten
• Bolts to 176 N m (130 ft. lbs.)
CHECKING RING GEAR RUN OUT
Measure
1. Ring gear run out.
• Mount a dial indicator to the carrier. The dial
indicator stem should rest on the back face of
the ring gear.
• Loosen the adjusting nut opposite the ring
gear enough to n otice end play on the
indicator.
• Tighten the same adjusting nut just enough to
have 0.000-inch end play on the indicator.
• Rotate the gear, and check for run out. If the
run out exceeds 0 .008-inch, rem ove the
differential, and determine the cause.
BACKLASH 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.
12
-INCH RING GEAR (ROCKWELL) 4B6-9
Figure 25— Adjusting Side Bearing Preload
Adjust
1. The bearing preload by tightening the adjusting nuts
(32) one notch each from 0.000 end play. Refer to
"C hecking Ring Gear Run O ut" (figure 25).
• Mount a dial indicator to the carrier (46). Place the
stem of the indicator onto the toe end of a tooth
(figure 26).
2. Backlash by moving the ring gear toward or away
from the pinion.
• If setting up the original ring and pinion gear
set, use the backlash reading obtained earlier.
• Set the backlash to 0.005 - 0.015-inch for new
gear sets.
• If the backlash is too high, move the ring gear
toward the pinion.
• If the backlash is too low, move the ring gear
away from the pinion.
Figure 2 6 — C hecking B acklash
F-04788