GMC 1989 Light Duty Truck Repair Manual page 234

4B7-4 LOCKING DIFFERENTIALS
11. If the backlash is too low, use a thinner 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 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 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
thrust washer with a thinner washer.
6. Rotate the pinion gear closest to the lock screw so
th a t one of th e te e th is p o in tin g d o w n w a rd
(perpindicular to the ring gear flange).
7. Insert a large tapered tool such as 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
indicator. 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 thrust
washer.
13. If the backlash is too low, use a thinner thrust
washer.
Thrust Block Clearance Adjustment
Install or C onnect
Left thrust washer (13) to the differential.
Cam unit to the differential.
Right thrust washer (8) to the differential.
Clutch plates with guide clips to the differential.
• Assemble alternatively as shown in figure 1.
Right side gear (10) to the differential.
Pinion shaft (18) and lock screw (3). Insert a large
tapered tool such as a screwdriver firmly between
each side gear and the pinion shaft.
A 1 to 2-inch telescoping gage between the side
gear faces, not the gear teeth.
• Measure the side gear spread (figure 6).
M easure
Remove the telescoping gage.
Measure the telescoping gage with a micrometer.
Measure the original thrust block at the outer corner
with a micrometer (figure 7).
If the th ru s t b lo ck th ic k n e s s is not 0.000 to
0.006-inch less than the side gear spread, adjust the
clearance by:
— Selecting a new thrust block the correct size to
obtain 0.000 to 0.006-inch clearance.
— Reshiming the right and/or left clutch disk
pack. The backlash m ust rem ain 0.002 -
0.010-inch.
ASSEMBLY OF THE DIFFERENTIAL
Install or C onnect (Figure 1)
1. Left thrust washer (13).
2. Cam unit. Refer to "Cam Unit Assem bly" in this
section.
3. Right thrust washer (8).
4. Right clutch plates with guide clips (19).
• Assembly alternatively as shown in figure 1.
5. Right side gear (10).
6. Thrust block (17), thrust washer (6), and pinion gear
(7).
• Place the pinion gears into the differential 180
degrees apart.
• Rotate the gears and thrust block into position.