GMC 1982 Light Duty Truck Service Manual page 464

4 B 4 -4 REAR A X LE
Fig. 4B4-7--Marking From Nominal on Pinion
1. Position differential side gears and new thrust washers
in differential case.
2. Position differential pinions and new thrust washers in
differential case. Align pinions with holes in differential
case.
3. Install pinion shaft in differential case. Align hole in
shaft with hole in case, then install lock pin. Peen hole
to prevent pin dropping out of case.
4. Position ring gear to case, then install cap screws.
Tighten cap screws
specifications.
5. With an arbor press, press differential side bearings
onto case using Tool J - 2 1051. Do not install shims at
this time.
6. Place differential case in carrier and install bearing
caps. Care should be taken to install caps in original
position. Use m ark placed on caps and c arrie r at
removal. Tighten caps just enough to keep bearing caps
in place.
7. Install dial indicator on carrier with indicator button
contacting back of ring gear, as in figure 4B4-6. Rotate
differential case and check for runout. If runout is
greater than .002", the assem bly should be removed
and the ring gear rem oved from the case. Again in­
stall differential case and check runout at differential
case flange.
8. Should runout of case flange be greater than .002" the
defect is probably due to bearings or differential case,
and should be corrected before proceeding further.
9. Position two screwdrivers between bearing cup and
carrier on opposite side of ring gear (away from dial
indicator side). Pull on screwdrivers and
differential case as far as possible toward the dial
indicator. Rock the ring gear to set the bearings. With
force still applied, set indicator at "0".
10. Reposition screwdrivers between bearing cup and
carrier on ring gear side. Pull on screwdrivers and force
differential case as far as possible toward center of
carrier. Record the indicator reading. This will be the
evenly and altern ately
force
total amount of shims needed (less preload) for setting
backlash later during assembly.
11. Remove differential from carrier.
DRIVE P IN IO N
In s ta lla tio n a n d A d ju s tm e n t o f D epth a n d Preload
Ring gears and pinions are supplied in matched sets
only. Matching numbers on both pinion and ring gear are
etched for verification. If a new gear set is being used, verify
the numbers of each pinion and ring gear before proceeding
with assembly.
On the button end of each pinion there is etched a plus
( + ) number, a minus (-) number, or a zero (0) number,
which indicates the best running position for each particular
gear set. This dimension is controlled by the shimming
behind the inner bearing cup. W henever baffles or oil
slingers are used, they become a part of the adjusting shim
pack.
F o r example: If a pinion is etched + 3 , this pinion
would require .003" less shims than a pinion etched "0 ".
This means by removing shims, the mounting distance of
the pinion is increased by .003" which is ju st w hat a + 3
etching indicates. O r if a pinion is etched - 3 , we would
want to add .003" more shims than would be required if the
pinions were etc h e d "0 ". By adding .003" shim s, the
mounting distance of the pinion was decreased .003" which
is ju st what a - 3 etching indicated. See figure 4B4-7.
If the old ring and pinion set is to be reused, measure
the old shim pack and build a new shim pack to this same
dimension. If baffle is in the axle assembly, it is considered
as part of the shim pack.
To change the pinion adjustm ent, shims are available
to
in thicknesses of .003", .005" and .010".
If baffle or slinger is bent or mutilated, it should be
replaced.
Measure each shim separately with a micrometer and
add together to get total shim pack thickness from original
build up.
If a new gear set is being used, notice the plus or minus
etching on both the old and new pinion, and adjust the
thickness of the old shim pack to com pensate for the
difference of these two figures.
F o r example: If the old pinion reads (+ 2 ) and the new
pinion is ( - 2 ) , add .004" shims to the original shim pack.
1. Determine proper inner shim pack (for setting pinion
depth) by using chart in figure 4B4-8.
2. Install inner shim pack and oil slinger in inner cup bore
and drive inner cup into position using Tool J - 2 1059
used with J-8092.
3. To the outer shim pack (for setting preload) add or
remove an equal amount as was added or removed from
the inner shim pack.
4. Install outer cup in carrier bore, using installer J-7818
with Drive Handle J-8092 as shown in figure 4B4-9.
5. Press inner pinion bearing cone and roller onto pinion
shaft using Installer J-9772 on arbor press as shown in
figure 4B4-10.
6. Install drive pinion and inner bearing cone and roller
assembly in differential carrier.
7. Install shims and outer pinion cone and roller on pinion
shaft using Tool J-5590 and companion
to press bearing onto pinion, as in figure 4 B 4 -11.
flange