Chevrolet 1980 Light Duty Truck Repair Manual page 75

Fig. 6B --Installing G aging Tool
spaced positions around the gear. Variation in readings
should not exceed .001". Position the dial indicator so that
indicator button is perpendicular to tooth angle and in line
with gear rotation.
14. If variation in backlash readings exceeds .002";
m easure ring gear and case runout as shown in figure 11B.
Gear runout should not exceed .003"; should runout exceed
this limit, check ring gear and case for deform ation a n d /o r
foreign m atter between case and gear.
15. If gear lash is not within limits, correct by
decreasing shim thickness on one side and increasing
th e sam e am ount.
thickness o f other shim
thickness m ust be m aintained at all tim es to m aintain proper
preload.
16. Backlash changes approxim ately .002" for each
.003" change in shim dimensions.
If backlash exceeds .008", increase the shim thickness
on the ring gear side, w hile decreasing the shim thickness
an equal am ount.
on the opposite side
than .005", decrease the shim thickness on the ring gear
side, w hile increasing the shim thickness on the opposite
an equal am ount.
side
D R IV E P IN IO N
Removal
1. R em ove differential as previously outlined.
2. Check torque required to rotate drive pinion, as
described under "Drive
Adjustment". If there is no preload reading, check for
looseness o f pinion assembly by shaking (push-pull) the
com panion flange. Looseness indicates the need for bearing
replacement.
3. Install H older J-8614-11 on flange by using tw o bolts
with flat washers, as shown in figure 12B. Position J-8614-
11 on flange so that the four notches are toward the flange.
4. R em ove pinion nut and washer.
5. Thread end o f J-8614-3 into sm all O .D . end o f J-
8614-2. Then with J-8614-11 installed as in step 3, insert
J-8614-2 into J-8614-11 and turn it 1/8 o f a turn to locked
position. R em ove flange by turning J-8614-3 w hile holding
J-8614-11 as shown in figure 13B.
T otal shim
I f backlash is less
Pinion - Installation and
REAR AXLE DIFFERENTIAL
6. To rem ove the drive pinion, first thread the original
pinion nut h alf way on the pinion, for thread protection.
7. Place the differential cover tem porarily back onto
the housing, using tw o screws. T his will prevent the pinion
from falling to the floor during removal.
8. Tap the end o f the pinion nut with a large hammer
and a soft drift, as show n in figure 14B.
Care m ust be taken not to damage pinion bearings
w hile rem oving pinion from carrier Insoect bearings nrd
cups for dam age and replace if needed.
9. R em ove the pinion oil seal and the front pinion
bearing. R em ove the cover and retrieve the drivt pinion
from the housing. Discard the pinion oil seal, nut, and
collapsible spacer. U se a new oil seal, nut and spacer on
reassembly.
Bearing Rem oval and Cup R eplacem ent
1. If front pinion bearing is to be replaced, drive outer
race from carrier using a drift in slots provided for this
purpose. Tap alternately on opposite sides o f the bearing cup
to avoid cocking.
2. If rear pinion bearing is to be replaced drive outer
race from carrier using a drift in slots provided for this
purpose.
3. R em ove rear pinion bearing from pinion shaft using
press plate J-8612 for 8-1/2" ring gear and J-22912 for 8 -7 /
8" ring gear as show n in Figure 15B.
Tighten nuts on tool until plates are under the bearing
inner race. Then set the tool on a press. M ake sure the plates
straddle the opening on the press. D o not position bolts
across the opening. To do so may bend the bolts when
pressure is applied. Press bearing from pinion. R ecord the
thickness o f shim rem oved from between bearing and pinion
head.
4. Inspect carrier pinion bearing bores and shoulders
for nicks. R em ove as necessary. Clean the bores and the
installation tools.
5. Lubricate both bearing cups w ith liberal am ounts of
hypoid lubricant.
6. Install the rear cup, with the large end against the
bore shoulder, using Installer J-8608 for 8-1/2" ring gear
and J-0270-14 for the 8-7/8" ring gear as shown in figure
16B.
7. Install the front cup, with the large end against the
bore shoulder, using Installer J -8 6 1 1-01 for the 8-1/2" ring
gear or J-7137 for the 8-7/8" ring gear as shown in figure
17B.
8. Check both bores to make sure cups are fully seated.
S e ttin g Pinion D ep th and in stallin g Pinion
Bearings
If the original ring gear and pinion and the pinion rear
bearing assembly are to be reinstalled, the original shim
thickness may be used.
R ing and pinion gear sets are m atched in a special test
m achine which perm its adjustment o f pinion depth in ring
gear until a point is reached where best operation and proper
tooth contact under load is obtained. A t this point, the
setting o f the pinion with reference to the centerline o f the
ring gear is indicated by the machine. T his setting m ay vary
slightly from the design or "nominal setting " due to
allowable variation in m achining the parts. W hen a pinion
is found haivng a plus or minus reading recorded in
4B-5