GMC 1989 Light Duty Truck, Repair Manual, Page: 247 / 998

8
V
2
-INCH RING GEAR 4C1-7
PINION INSTALLATION
13. Rotate the gage shaft slowly back and forth until the
dial indicator reads the greatest deflection (when the
indicator needle is centered between movement 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 num ber 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 13, record the dial
reading of 0.84 mm (0.033-inch) not 1.70 mm
(0.067-inch).
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 m any thou san d ths from the
nom inal setting. If the nom inal 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 and depth gaging tools.
19. In sta ll the c o rre c t p in io n shim to the p in ion
according to this procedure.
-►<- Install or C o nnect
Tools Required:
J 8609-01 Rear Pinion Bearing Cone Installer
J 22388 Pinion Oil Seal Installer
J 8614-01 Pinion Flange Remover
J 5590 Rear Pinion Bearing Cone Installer
• The bearing cups should have been installed in
“ Pinion Depth A djustm ent” in this section.
1. The pinion inner bearing (5) using J 8609-01.
• Press the bearing onto the pinion until the
bearing cone seats on the pinion shims.
2. A new collapsable spacer (4).
• Lubricate the pinion bearings with axle lubricant.
3. Pinion (7) to the axle housing.
4. Outer pinion bearing (39) onto the pinion using
J 5590.
• Hold the pinion forward from inside the case
while driving the bearing onto the pinion.
5. Pinion oil seal (38) using J 22388 (figure 14).
6. The pinion flange (37) to the pinion by tapping it with
a rawhide hammer until a few threads show through
the pinion flange.
7. The pinion washer (36) and a new nut (35) while
holding the pinion flange with J 8614-01 (figure 15).
Tig h ten
• The nut until the pinion end-play is just taken
up. Rotate the pinion while tightening the nut
to seat the bearings. Once there is no end-play
in the pinion, the preload torque should be
checked.
• R em ove J 8614-01. U sing an in c h -p o u n d
torque wrench, check the pinion preload by
rotating the pinion with the wrench. Preload
should be 2.2 to 2.8 N m (20 to 25 in. lbs.) on
new bearings, or 1.1 to 1.6 N m (10 to 15 in.
lbs.) for used bearings (figure 16).
• If the preload torque is below the preloads
given above, continue torquing the nut in small
increm ents. C heck the preload after each
tig hte nin g. Each tig h te n in g increases the
bearing preload by several pounds. If the
bearing preload is exceeded, the pinion will
have to be removed, and a new collapsible
spacer installed.
• Once the preload has been obtained, rotate
the pinion several times to make sure that the
bearings have seated. Recheck the preload,
and adjust if necessary.
8. Differential case. Refer to “ Backlash A djustm ent” in
this section.
DIFFERENTIAL CASE ASSEMBLY
Install or C onnect (Figure 1)
Tools Required:
J 8107-4 Differential Side Bearing Remover
Plug
J 8092 Driver Handle