Chevrolet 1980 Light Duty Truck Repair Manual page 98

4B-30 REAR AXLE DIFFERENTIAL
Fig. 20F~ M arking From Nom inal on Pinion
M easure each shim separately with a m icrom eter 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 m inus
etching on both the old and new pinion, and adjust the
thickness o f the old shim pack to com pensate for the
difference o f these tw o figures.
For example: If the old pinion reads ( + 2) and the new
pinion is (-2 ), add .004" shim s to the original shim pack.
1. D eterm ine proper inner shim pack (for setting pinion
depth) by using chart in figure 2 IF.
2. Install inner shim pack and oil slinger in inner cup
bore and drive inner cup into position using T ool J -2 1059
used with J-8092.
3. To the outer shim pack (for setting preload) add or
rem ove an equal am ount as was added or rem oved from the
inner shim pack.
4. Install outer cup in carrier bore, using installer J-
7818 with D rive H andle J-8092 as shown in figure 22F.
5. Press inner pinion bearing cone and roller onto
pinion shaft using Installer J-9772 on arbor press as shown
in figure 23F.
6. Install drive pinion and inner bearing cone and roller
assembly in differential carrier.
7. Install shim s and outer pinion cone and roller on
pinion shaft using T ool J-5590 and com panion flange to
press bearing onto pinion, as in figure 24F.
8. Install flange holding bar and install washer and nut
on pinion shaft. Torque nut to 255 ft. lbs.
9. R em ove holding bar and with an inch pound torque
wrench m easure rotating torque. Rotating torque should be
10 to 20 in. lbs. with original bearings or 20 to 40 in. lb.
with new bearings.
Torque reading to start shaft
disregarded.
10. If torque requirements (preload) are not to
specifications, adjust shim pack as necessary. Increase the
outer shim pack to reduce rotation torque. D ecrease shim
pack to increase rotating torque.
11. R em ove nut, washer and flange from pinion shaft.
O V E R H A U L M A N U A L
install oil seal.
specifications.
D IF F E R E N T IA L CASE
Preload and A d ju s tm e n t
into housing. Install bearing caps in their proper position
and tighten screws just enough to hold the bearing cups in
place.
contacting back o f ring gear, as in figure 19F.
housing on ring gear side o f case, and pry ring gear into
m esh with pinion gear as far as it w ill go. R ock ring gear
to allow bearings to seat and gears to mesh. W ith force still
applied, set indicator to "0".
and pry ring gear as far as it will go. N o w take an indicator
reading. Repeat until the sam e reading is obtained every
time. This reading will be the necessary am ount o f shims
between the differential case and differential bearing on the
ring side gear. R em ove differential bearing from the ring
side and assem ble proper am ount o f shims. R eassem ble
bearing.
side o f ring gear. To determine the am ount o f shim s needed
here, use the follow ing method.
gear side o f case from the reading obtained and recoreded
in step 10 o f Differential Case-Reassem bly.
com pensate for preload and backlash.
R eassem bly was .085", and the shim s installed on ring gear
side o f case was .055", the correct am ount o f shim will be
.085" - .055" + .015" = .045".
the proper bearing preload and backlash) and install side
bearing.
In stallatio n
in figure 15F.
location, then install differential case into carrier.
location as indicated by marks m ade at disassem bly. Install
cap screws finger tight. R otate differential assem bly and rap
on case with a soft faced ham m er to ensoure proper seating
o f case in carrier.
specifications.
turning must be
at four equally spaced points around the ring gear. Backlash
must be held to .004" to .009" and must not vary more than
.002" between positions checked.
bearing shim pack should be corrected to bring backlash
within limits.
12. Install oil slinger, gasket and using T ool J-22804
13. Install flange, washer and nut. Torque nut to
1. Place differential assembly (with pinion assem bled)
2. Install dial indicator on carrier with indicator button
3. Place tw o screwdrivers between bearing cup and
4. R eposition screw drivers on opposite side o f ring gear
5. R em ove the differential bearing from the opposite
a. Subtract the size o f shim pack just installed on ring
b. To this figure, add an additional .015" shim s to
Example: If reading in step 10 o f Differential Case-
6. Install shim s as indicated in step 5, (which will give
1. Spread differential carrier, using spreader as shown
2. Install differential bearing outer races in their correct
3. Install differential bearing caps in the correct
4. R em ove spreader and
5. Install dial indicator and check ring gear backlash
6. W henever backlash is not within lim its, differential
torque cap bolts to