TM 5-3805-260-24
Differential Backlash and Bearing Adjustment:
NOTE. The following procedure controls backlash and bearing
preload. This procedure gives the same results for used and
new bearings
1 Fasten pinion housing (7) to carrier (4). If original gears,
carrier assembly and housing are used again, use the
original thickness of shims (5) If any of these parts are
replaced, install a shim pack thickness of 80% of a new full
shim pack.
NOTE: Shim pack (5) thickness may have to be changed
when adjusting the tooth contact pattern
2 Tighten eight bolts (6) to a torque of
270 + 25 N
m(200 + 18 lb ft.)
3 With housing (7) fastened to carrier (4), position pinion (8)
in the vertical position, downward.
4 Lubricate bearings and install bearing cups on the
differential bearings to protect them.
5 Install differential in carrier (4) with bevel gear (12) on side
opposite the pin hole in carrier (4)
6. Install caps (1) and (14) and adjustment rings (2) and (15).
Adjustment rings (2) and (15) must turn freely.
7. Tighten one bolt (16) on caps (1) and (14) to a torque of 70
N m (50 lb ft.) and the other bolt on caps (1) and(14) to a
torque of
5 N-m (4 lb ft )
8 Tighten adjustment rings (2) and (15) until there is a small
amount of backlash and zero preload on differential
bearings
9 Reposition the assembly so that pinion shaft (8) is In the
horizontal position and measure the torque required to
rotate pinion (8) Record this measurement.
10 Tighten adjustment ring (15) while turning bevel gear until
there is zero backlash
11 Loosen adjustment ring (15) to the nearest lock position
(maximum of one lug movement).
12. Tighten adjustment ring (2) until the torque required to
rotate pinion (8) increases to 0.2 to 0.6 N-m (1 to 4 Ib.in.)
over the torque reading in Step 9.
13 Put a mark (A) on cap (1). Put a mark (B) on adjustment
ring (2) three lugs from mark (A). Tighten adjustment ring
(2) until mark (B) is in alignment with mark (A).
14. If lock can not be installed, tighten adjustment nut (2) until
lock can be installed.
15. Measure the backlash between the ring gear and pinion.
The backlash must be 0.20 to 0.42 mm (.008 to .017 in.).
16 If backlash is too much, loosen adjustment ring (2) and
tighten adjustment ring (15) the same amount.
17 If backlash is not enough, loosen adjustment ring (15) and
tighten adjustment ring (2) the same amount.
NOTE The differential preload will be kept only if one
adjustment ring is loosened and the other adjustment ring
is tightened the same amount.
18. Tighten bolts(16) in caps (1)and (14) to a torque of
475 + 50 N m (350 + 37 Ib.ft.)
19. After the backlash and preload adjustments have been
made, the tooth contact between pinion (8) and ring gear
(12) must then be checked Do the procedure that follows:
a. Put a small amount of a mixture of paint pigment and
oil on the teeth of ring gear (12)
b Turn pinion (8) In both directions.
c The correct area of tooth contact is located equally on
both sides and starts near the inside end of the teeth of ring
gear (12) See Illustration B for an example of the correct area
of tooth contact.
20. If the marks made on the teeth of ring gear (12) look like
the marks in Illustration C, do the procedure that follows:
a. Add some of shims (5)
b. Loosen bolts (16) to the torque indicated in Step 7
c. Do Steps 15 through 19 again.
21 If the marks made on the teeth of ring gear (12) look like
the marks in Illustration D, do the procedure that follows:
a. Remove some of shims (5).
b. Loosen bolts (16) to the torque indicated in Step 7
c. Do Steps 15 through 19 again.
NOTE: Always make sure the backlash adjustment is
correct before an adjustment is made to the area of tooth
contact Several adjustments to the backlash and tooth
contact may be necessary to get the correct adjustments.
22. After adjustments are made, remove the paint from the
gears.
23 Install locks and bolts on caps (1) and (14).
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