GMC 1982 Light Duty Truck Service Manual page 500

4B6-18 REAR AXLE
Fig. 4B6-9H--Cam Plate and Clutch Discs
• Reaction blocks (4 sizes).
• Thrust ring.
• Right side shim (4 sizes).
• Left side guide clips.
A ttem pts to service other components will disturb
critical clearances and may result in differential failure. If
reaction blocks or right side shim must be replaced, the
original pieces must be carefully measured for thicknes and
replaced with a piece of the same size.
C A M /C L U T C H SERVICE
D isa sse m b ly
If cam plate or clutch discs must be replaced, the cam
gear sub-assembly must be serviced as follows: Refer to
Figure 4B6-9H.
1. Measure and record overall length of gear assembly
(front face of gear to back side of thrust ring, include
shim). This dimension will be needed to reassemble
unit if thrust ring is replaced. DO NOT REPLACE
TH RUST RING U N L E SS NECESSARY. If ring is
excessively worn or scored, check bore in case for
scoring. If bore is scored, replace entire differential.
2. With gear hub end up, compress disc pack and install
jaws of split ring bearing removed (J-22912) between
the thrust ring and the top eared disc. Bevel side of
bearing remover should face up toward thrust ring.
3. Place cam gear assem bly with bearing remover
attached in an arbor press supporting the bearing
remover on both sides.
4. Install a 1-1/2" to 1-3/4" diameter plug (J-8107-4) on
gear hub. Press against plug with ram of press to
remove thrust ring. Keep all components in the proper
order.
R e a sse m b ly
Replace cam plate and/or clutch disc as necessary and
reassemble as follows:
1. Place gear on bench with hub end up.
2. Assemble cam plate with cam form down to mate with
cam form on gear.
3. Assemble onto cam plate (2) eared discs, (1) splined
disc, and (1) wave spring alternately as shown Fig.
4B6-9H.
4. Assemble onto gear hub: (4) eared discs and (3) splined
discs alternately as shown. Begin and end with an eared
disc.
5. Locate cam gear assembly in arbor press with hub end
up. Place thrust ring on gear hub and press to shoulder
making sure that ring is square with hub.
a. Compress disc pack by pushing down on the discs to
keep the splined discs from becoming wedged
between the thrust ring and gear shoulder while
pressing the sub-assembly together. Completed sub-
assembly should be checked for proper disc sequence.
Also, make sure the first splined disc (large spline) is
properly located on the cam plate.
R e a sse m b ly
1. Install (6) clutch pack guide clips on the ears of the
cam gear clutch pack using grease for retention.
2. Install cam gear assembly and original shim in right
side case half. If a new thrust ring has been pressed on
the cam gear, reshimming may be necessary. Measure
the overall length of the new cam gear assembly,
including the shim and compare to the dimension
obtained in Step A of cam gear service section. If the
length of the new assembly varies by more than .003"
larger or smaller than the original dimension,
reshimming will be necessary. Select a shim which will
result in a reading closest to the original.
Incorrect shimming will disturb critical
N O T IC E :
clearance dimensions and may result in differential
failure.
3. Install right side reaction block on gear face with
button side of block facing up. Use original block unless
severely scored or worn. If new block is used, determine
face-to-face thickness of original block with calipers
and replace with a service block of the same thickness.
Incorrect block thickness will disturb critical
N O T IC E :
clearances and may result in differential failure.
4. Preassemble pinions and pinion thrust wahsers on
pinion yoke. Index yoke to proper position and install in
housing with center over button end of reaction block.
A light tap on the yoke may be needed to seat it in the
housing.
5. Install left side reaction block on the yoke with flange
side up. Use original block unless severely scored or
worn. If new block is used, determ ine face-to-face
thickness of original block with calipers and replace
with a service block of the same thickness.
Right and left side reaction blocks may not be
N O T IC E :
the same thickness. If blocks are broken or cannot be
accurately measured
differential must be replaced. Incorrect block thickness
will disturb critical clearances and may result in
differential failure.
6. Install governor assem bly and latching barcket in
for thickness, the entire