Pinion And Cage Assembly; Differential And G E A R - GMC 1982 Light Duty Truck Service Manual

4 B 5 - 1 0 REAR A X LE
Selecting Pinion C ag e Shim Pack Thickness
A means of accurately installing a new pinion and cage
assembly into the carrier is to mathematically calculate the
proper pinion cage shim pack thickness.
The following are the procedures to use:
1. Measure the thickness of the original shim pack used
with the gear set being replaced. Use a micrometer or
vernier gage. Record this measurement for future use.
2. Observe the " P C " or variation number on the original
pinion being replaced. If this number is a plus ( ) value,
subtract it from the original shim pack measurement
taken in item " 1 " . If the variation number is a minus
(-) value, add it to the measurement from item " 1 " .
Make a note of this value.
The value calcu lated in item "2" will estab lish a
"standard shim pack thickness", without a variation.
This value will be used in calculating the shim pack
thickness used with a new pinion and gear set.
3. Observe the " P C " or variation number on the new
pinion, (locations of the " P C " num ber are shown
above). Add or substract this number as indicated by
the variation sign ( add or - substract) from the
calculated "standard shim pack thickness" determined
in item " 2 " .
T he resulting answer indicates the thickness (in
thousandths) of the new shim pack to be used. Refer to
the following examples which cover all the possible
combinations of or - original and new " PC " variations.
After calculating the shim pack thickness, assemble
the new pinion and cage assembly with the correct shim
pack into the carrier as follows:
R em em b er all drive
m anufactured and sold only in matching sets. Therefore, if
either a pinion or a ring gear should require replacement,
both must be replaced in a matching set.
pinion and gear sets are
Pinion and C ag e Assembly
In sta lla tio n
1. Position the correct shim pack between the pinion cage
and carrier.
U se a minimum o f three (3) shim s per pack. If the pack
is made up from various thicknesses of shim s, locate
thinnest shims on both sides o f the pack for maximum
sealing ability.
2. Install the pinion and cage assembly with shims into
carrier and tap into position with soft mallet.
3. Install pinion cage capscrews. Tighten capscrews to the
correct torque.
After the differential and gear assembly is installed into
4.
carrier, make a gear tooth contact check (Refer to
Section 4B ).
D ifferen tial and G ear
Assem bly
NOTICE: The ring gear m ust be heated before
assembling onto the case half, otherwise damage to the
case half will result.
Proper service replacement of the differential ring gear
onto the differential case half is necessary for correct gear
a d ju stm ent and longer
Fig. 4B5-20--lnstalling Flange
drive unit service life.