Figure 3-14. Adjusting backlash.

TM 10-3930-631-34

(15)If pinion is a minus .005 inches (etched

shown on figure 3-14. Backlash should be between

2.645) the .005 inches has been subtracted from the

.005 and .010 inch (0.127-0.254 mm).

theoretical setting therefore the amount of shims

required is found as follows:

2.715 total

-2.645,

.070 thickness of shims required

Note

The above dimensions are examples.

Use the exact one-half outside diameter

as measured plus the distance measured

in (12) above. Subtract the dimension

etched on the pinion to get the shim

thickness required in the differential of the

truck being repaired.

(16)Remove differential assembly from

carrier and remove tool and bearing from carrier.

(17)Install proper amount of shims on pinion.

Measure shim thickness with a micrometer for exact

installation.

(18)Install pinion (23, fig. 3-8) in carrier

housing. Install rear bearing cone (19), washer (18),

tab washer (17) and nut (16) on pinion shaft. Tighten

lock nut (16) so that 15-25 pound feet (2.0-3.4 m-kg)

are required to rotate pinion shaft. Bend tabs on

washer to secure nut.

Note

Install a /2-13 screw in threaded hole in end

of shaft and rotate with a torque wrench to

get proper reading Remove screw from

shaft.

(19)Place the differential assembly in the

Figure 3-14. Adjusting backlash.

carrier. Move the ring gear toward the pinion so that

all backlash is taken up.

(20)Install bearing caps (36, fig. 3-8) on

(28)Move ring gear by hand in a clockwise

carrier and secure with screws (35). Check marks to

direction until all play or movement is eliminated

be sure bearing caps are installed properly. Secure

between ring gear and pinion.

screws with lock wire (34).

(29)With stem of dial indicator against the

(21)Install bearing adjusting nuts (31) in

side (face flank) of ring gear tooth, move ring gear in

carrier. Tighten both nuts until they contact the

opposite direction and read backlash on dial

bearing caps. Loosen the adjusting nut on op- posite

side from ring gear until ring gear and differential are

indicator. Backlash should be in tolerance shown

loose in the bearings (approximately two to three

above.

revolutions).

(30)Check backlash at four positions on ring

(22)Tighten other adjusting nut (nut next to

gear approximately 90 degrees apart.

ring gear) against bearing until all backlash between

(31)If adjustment is required, turn adjusting

ring and pinion gear has been eliminated.

nuts one notch at a time. Turn each adjusting nut

(23)Loosen ring gear side adjusting nut

exactly the same distance to preserve correct

three to four notches.

(24)Tighten other adjusting nut one to two

bearing preload.

notches more. Do not tighten adjusting nuts to a

(32)To increase backlash loosen adjusting

torque of more than 25 pound feet (3.4 m-kg). Do

nut on side of carrier nearest ring gear and tighten

not exceed two notches of tightening.

opposite adjusting nut.

To decrease backlash,

(25)Wrap a cord around differential case

loosen adjusting nut on side away from ring gear and

and attach a spring scale to loose end. Start pulling

tighten opposite nut.

on the scale and note effort to rotate case. Case

(33)When backlash is adjusted, install locks

should start and maintain rotation at less than 3

pounds (1.35 kg) pull.

(30, fig. 3-8), lock washers (29) and screws (28) to

(26)Make, final backlash adjustment as

securely lock adjusting nuts.

follows:

e. Installation.

(27)Install a dail indicator on carrier as

(1) Aline dowel pin and install carrier

3-14