Chrysler RAM TRUCK 2500 1994 Service Manual page 127

3 - 20 REAR SUSPENSION AND AXLE •
(19) Remove the tools from the shaft. Rotate the
pinion several complete revolutions (both directions)
to additionally seat the bearing rollers.
CAUTION: Never loosen the pinion gear nut to de­
crease the pinion gear bearing preload torque. If the
specified preload torque is exceeded, a replacement
collapsible spacer must be installed. The torque se­
quence will have to be repeated.
(20) Measure the pinion bearing preload torque by
rotating pinion shaft with a Newton-meter or an
inch-pound torque wrench. The correct bearing pre­
load torque is 2-4 N-m (20-30 i n . lbs.). This torque
value is with replacement bearings and pinion nut
tightened to a minimum of 285 N-m (210 ft. lbs.)
torque (Fig. 25)
When using original pinion rear bearing and
a replacement front bearing. The correct pre­
load torque is 1 N-m (10 in. lbs.) torque plus the
torque measured and recorded during disas­
sembly.
Fig. 25 Bearing Preload Torque Measurement
The bearing preload torque should be con­
stant during a complete revolution of the drive
pinion gear shaft. If preload torque varies
while rotating the shaft, there is an internal
binding that must be corrected before assem­
bly.
(21) I f specified torque is not obtained, tighten the
nut i n small increments until preload torque is ob­
tained.
The differential will be unacceptable for use
i f the final nut torque is less than 285 N-m (210
ft. lbs.) torque. If preload torque is not within
the specified range this is also unacceptable.
DIFFERENTIAL CASE INSTALLATION
(1) Apply a coating of hypoid gear lubricant to the
differential bearings, bearing cups and threaded ad­
justers. A dab of grease can be used to keep the ad­
justers i n position. Carefully position the assembled
differential case i n the housing.
(2) Observe the reference marks and install the
differential bearing caps at their original locations
(Fig. 26).
Fig. 26 Bearing Caps & Bolts
(3) Install the bearing cap bolts (Fig. 26). Tighten
the upper bolts to 14 N-m (10 ft. lbs.) torque. Tighten
the lower bolts finger-tight until the bolt head is
lightly seated.
DIFFERENTIAL BEARING PRELOAD AND RING
GEAR BACKLASH ADJUSTMENT
The following must be considered when adjusting
bearing preload and gear backlash:
• The maximum ring gear backlash variation is
0.003 inch (0.076 mm)
• Mark the gears so the same teeth are meshed dur­
ing all backlash measurements
• Maintain the torque while adjusting the bearing
preload and ring gear backlash
• Excessive adjuster torque will introduce a high
bearing load and cause premature bearing failure.
Insufficient torque can cause excessive differential
case free-play and ring gear noise
• Insufficient adjuster torque will not support the
ring gear correctly. This can cause excessive differen­
tial case free-play and ring gear noise.
The differential bearing cups will not always
immediately follow the threaded adjusters as
they are moved during adjustment. Ensure ac­
curate bearing cup responses to the adjust­
ments. Maintain the gear teeth engaged
(meshed) as marked. The bearings must be
seated by rapidly rotating the pinion gear a
half turn back and forth. Do this five to ten
times each time the threaded adjusters are ad­
justed.
(1) Use Wrench C-4164 to adjust each threaded ad­
juster inward (Fig. 27). Adjust until the differential
bearing free-play is eliminated. Allow some ring gear