GMC 1990 Light Truck Repair Manual page 140

4B1-6 7' fe AND 7s/s-INCH RING GEAR AXLES
Tighten
£
• Stud nut to 2.2 N m (20 in. lbs.).
6. Rotate the gage plate and bearings several
complete revolutions to seat the bearings.
7. Tighten the stud nut until a torque of 1.6 to 2.2 N m
(15 to 25 in. lbs.) is obtained to keep the gage plate
in rotation.
8. Assembly J 21777-45, J 23597-11, and J 8001 to the
differential bearing bores as shown in figure 9.
• The bearing bores must be clean and burr
free.
9. Install the side bearing caps and tighten the bolts
finger tight.
10. Rotate the gage plate until the gaging areas are
parallel with the disks.
11. Position the gage shaft assembly in the carrier so
that the dial indicator rod is centered on the gage
area of the gage block.
12. Set the dial indicator at zero. Push the indicator
down on the indicator shaft until the needle rotates
approximately 3 U of a turn to the right. Tighten the
dial indicator in this postion.
13. Rotate the gage shaft slowly back and forth until the
dial indicator reads the greatest deflection (when the
indicator needle is centered between moving to the
left and to the right).
14. At the point of greatest deflection, set the dial
indicator to zero. Repeat the rocking action of the
gage shaft to verify the zero setting.
15. Rotate the gage shaft until the dial indicator rod
does not touch the gage block.
16. Record the actual number on the dial indicator and
not the number which represents how far the needle
travels. This is the nominal pinion setting.
EXAMPLE: If the indicator needle moved to the left
1.70 mm (0.067-inch) to a dial reading of 0.84 mm
(0.033-inch) as shown in figure 10, record the dial
reading of 0.84 mm (0.033-inch) not 1.70 mm
(0.067-inch).
The dial indicator should be in the 0.50 to the 1.27
mm (0.020 to 0.050-inch) range.
17. Check the pinion face for a pinion adjustment mark.
This mark indicates the best running position for the
pinion from the nominal setting.
• If the pinion is stamped with a plus number,
add that many thousandths to the nominal
setting. If the nominal setting is 0.033-inch and
the pinion is marked +2, the correct shim
depth would be 0.033-inch + 0.002-inch =
0.035-inch.
• If the pinion is stamped with a minus number,
subtract that many thousandths from the
nominal setting. If the nominal setting is
0.033-inch and the pinion is marked -2, the
correct shim depth would be 0.033-inch -
0.002-inch = 0.031-inch.
• If the pinion has no plus or minus marked on
the pinion, use the nominal pinion setting to
select a shim.
18. Remove bearing caps (31) and depth gaging tools.
19. Install the correct pinion shim (19) according to this
procedure to the pinion.
DIFFERENTIAL CASE ASSEMBLY
♦«- Install or Connect (Figure 1)
Tools Required:
J 25299 Differential Side Bearing Installer
J 8092 Driver Handle
J 8107-2 Differential Side Bearing Remover
Plug
• Lubricate all parts with rear axle lubricant.
1. Side gear thrust washers (28) to the side gears (26).
2. Side gears (28) to the differential case (24).
• Place the side gears in place on the same side
as removed.
3. Pinion gears (28) to the differential without the thrust
washers (27).
• Place one pinion gear onto the side gears and
rotate the gears until the pinion is exactly
opposite from the differential opening.
• Place the second pinion gear onto the side
gears so that the pinion gear holes line up.
• Rotate the pinion gears into place, and veryify
that the pinion gears line up with the pinion
shaft holes.
4. Pinion thrust washers (27).
• Rotate the pinion gears toward the differential
opening just enough to slide in the pinion
thrust washers.
5. Pinion shaft.
6. Pinion shaft screw.
• Check that the mating surfaces of the differential
case and the ring gear are clean and burr free.
7. Ring gear (20) to the differential case (24) (figure
11).
• Thread two left-hand threaded studs into the
ring gear on opposite sides.
• Place the ring gear onto the case, and align
the studs with the holes in the case.
8 New ring gear bolts (25).
• Tighten the ring gear bolts alternately in
stages gradually pulling the ring gear onto the
differential case.
Tighten
• The ring gear bolts in sequence to 120 N m
(90 ft. lbs.).
9. Differential side bearings (22) using J 25299,
J 8092, and J 8107-2 (figure 12).
• Place J 8107-2 into the differential on the side
opposite of bearing installation to protect the
differential case.
• Drive the bearing onto the case using J 25299
and J 8092.
10. Differential case (24) to the axle housing. Refer to
" Side Bearing Pre-Load Adjustment" in this section.
SIDE BEARING PRE-LOAD ADJUSTMENT
• The side bearing pre-load adjustment must be
made before installing the pinion.
• The case side bearing pre-load is adjusted by
changing the thickness of both the left and right
shims equally. This will maintain the original
backlash.