GMC 1989 Light Duty Truck Repair Manual page 158

8
4B2-10 1 / 2-INCH RING GEAR
11. For an initial backlash setting, move the ring gear
away from the pinion by subtracting
the ring gear side shim pack and adding
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.
.
Install a dial indicator to the case using a magnetic
3.
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 perpendicular to the
tooth angle (figure 24).
Install the differential caps (10) and bolts (18).
5.
T ighten
• The bolts to 80 N-m (60 ft. lbs.).
6
. 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
p oint w ithin 0.05 mm (0.002-inch). If the
b a c k la s h v a rie s
0 002
( . -inch), check for burrs, a distorted case
flange, uneven bolting conditions, or foreign
matter between the case and the ring gear.
Backlash at the minimum lash point measured
should be between 0.13 and 0.23 mm (0.005 and
0.009-inch) for all new gear sets.
0 . 010 -inch from
0 010
. -inch
m o re th a n 0.05 mm
8 . If the backlash is not within specifications, move the
ring gear in or out from the pinion by increasing the
th ic k n e s s of one s h im , and d e c re a s in g th e
thickness of the other shim by the same amount.
This will maintain the correct rear axle side bearing
preload.
• Moving 0.003-inch worth of shim from one side
of the differential to the other will change the
backlash adjustment by
9. Recheck the backlash and correct as necessary.
FINAL ASSEMBLY
|-K -| Install or C onnect (Figure 1)
1 . Drive axles. Refer to the proper service manual.
2. A new cover gasket and the cover (12).
T ighten
• The cover bolts (14) to 27 N m (20 ft. lbs.).
3. Axle housing to the vehicle. Refer to the proper
service manual.
Lubricant to the rear axle.
GEAR TOOTH
PATTERN CHECK
Checking the ring gear to pinion tooth pattern is to be
done only after setting up the axle according to the
methods in this section. The pattern check is NEVER to
be used as an initial check, or instead of checking pinion
depth and backlash adjustments. This check is only to be
used to verify the correct adjustm ent of the gear set after
setup.
1 . Wipe all oil out of the carrier, and carefully clean
each tooth of the ring gear (figure 25).
2. Use gear marking compound 1052351 or equivalent
and apply this mixture sparingly to all ring gear
teeth, using a m edium-stiff brush. When properly
used, the area of pinion tooth contact will be visible
when hand load is applied.
3. Tighten the bearing cap bolts to the specified
torque.
0 002
. -inch.