Cam Unit Assembly - 9 1/2-Inch; Adjustment Of The Differential - GMC T Series 1994 Repair Manual

• Differential case for cracks and scoring.
• Thrust sleeve for excessive wear. Do not replace
the thrust sleeve unless necessary. Inspect the
side gear bore for scoring. If scoring is present,
replace the entire differential.
• All parts and replace if necessary.
CAM UNIT ASSEMBLY - 7 1/2, 7 5/8, AND 8
1/2-INCH
Install or Connect (Figures 1 and 3)
1. Cam plate (16) to the side cam gear (21).
2. Wave washer (15).
3. Clutch plates (12) (7 1/2 and 7 5/8 = 8 plates. 8 1/2
= 10 plates).
• Alternate the plates as shown in figure 1.
4. Retaining ring (22) (figure 3).
5. Guide clips (20) to the clutch plates (12).
• Use grease in the clips to hold them in place on
the plates.

CAM UNIT ASSEMBLY - 9 1/2-INCH

-►+ Install or Connect
1. Cam plate (16) to the side cam gear (21).
2. Wave washer (15).
3. Clutch plates (12).
• Alternate the plates as shown in figure 1.
4. Thrust sleeve (14).
• Press the thrust sleeve flush with the side gear
disc splines.
5. Guide clips (20) to the clutch plates (12).
• Use grease in the clips to hold them in place on
the plates.
A. If the side cam gear or side thrust sleeve has
been replaced, measure and record the overall
length of the gear assembly from the front of
the gear to the back of the side thrust sleeve
(14) including the side gear thrust washer (13).
B. Compare this reading with the reading obtained
earlier in this section.
C. If the new reading is more than 0.0762 mm
(0.003 inch) higher or lower than the original,
select a thrust washer that will return the read­
ing closest to the original reading.

ADJUSTMENT OF THE DIFFERENTIAL

• If it is necessary to replace the cam gear, right side
gear, or thrust block, the entire differential must be
adjusted. The differential is adjusted by using
selective thickness thrust washers behind each
side gear and selective thickness reaction blocks.
• It is important to build up the differential properly.
The proper clearance between parts is critical to
the operation of the unit.
• There are three adjustments needed:
(1) Left side gear backlash.
(2) Right side gear backlash.
(3) Thrust block clearance.
Left Side Gear Backlash Adjustment
1. Install the cam unit and side thrust washer (13) to
the flange end of the case.
2. Place the pinion gears (7) and side gear thrust
washers into the differential.
• Align them with the pinion shaft hole.
3. Press down the side gear, and install the pinion
shaft (18) and lock screw (3).
• If the side gear cannot be pressed down far
enough to install the pinion shaft, replace the
side gear thrust washer with a thinner washer.
4. Rotate the pinion gear closest to the lock screw so
one of the teeth is pointing downward (perpendicu­
lar to the ring gear flange).
5. Insert a large tapered tool, like a screwdriver, firmly
between the side gear and the pinion shaft.
6. Mount a dial indicator to the ring gear flange and
place the stem of the indicator on one of the teeth on
the pinion gear closest to the lock screw (figure 5).
7. Pull the pinion gear firmly into its seat, and rotate
the gear back and forth while reading the dial indi­
cator. Record the reading.
8. Repeat steps 4 through 7 on the opposite pinion
gear.
9. The backlash should be between 0.254 and
0.457 mm (0.010 and 0.018 inch).
10. If the backlash is too high, use a thicker side gear
thrust washer.
11. If the backlash is too low, use a thinner side gear
thrust washer.
Right Side Gear Backlash Adjustment
1. Assemble the clutch plates.
• Alternate the plates as shown in figure 1.
2. Assemble the guide clips (19) to the plates.
• Use grease in the clips to hold them in place on
the plates.
3. Install the side gear thrust washer (8), clutch plate
assembly (9), and right side gear to the differential.
4. Place the pinion gears (7) and thrust washers (6)
into the differential.
• Align them with the pinion shaft hole.
5. Press down on the side gear, and install the pinion
shaft (18) and lock screw (3).
• If the side gear cannot be pressed down far
enough to install the pinion shaft, use a thinner
side gear thrust washer.
6. Rotate the pinion gear closest to the lock screw so
that one of the teeth is pointing downward (perpen­
dicular to the ring gear flange).
7. Insert a large tapered tool, like a screwdriver, firmly
between the side gear and the pinion shaft.
8. Mount a dial indicator to the ring gear flange, and
place the stem of the indicator on one of the teeth on
the pinion gear closest to the lock screw (figure 5).
9. Pull the pinion gear firmly into its seat, and rotate
the gear back and forth while reading the dial indi­
cator. Record the reading.
10. Repeat steps 6 through 9 on the opposite pinion
gear.
11. The backlash should be between 0.051 and 0.243
mm (0.002 - 0.010 inch).
12. If the backlash is too high, use a thicker side gear
thrust washer.
13. If the backlash is too low, use a thinner side gear
thrust washer.