TM 5-3805-260-24Differential Backlash and Bearing Adjustment:NOTE. The following procedure controls backlash and bearingpreload. This procedure gives the same results for used andnew bearings1 Fasten pinion housing (7) to carrier (4). If original gears,carrier assembly and housing are used again, use theoriginal thickness of shims (5) If any of these parts arereplaced, install a shim pack thickness of 80% of a new fullshim pack.NOTE: Shim pack (5) thickness may have to be changedwhen adjusting the tooth contact pattern2 Tighten eight bolts (6) to a torque of 270 + 25 Nm(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 thedifferential bearings to protect them.5 Install differential in carrier (4) with bevel gear (12) on sideopposite 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 70N m (50 lb ft.) and the other bolt on caps (1) and(14) to atorque of 5 N-m (4 lb ft )8 Tighten adjustment rings (2) and (15) until there is a smallamount of backlash and zero preload on differentialbearings9 Reposition the assembly so that pinion shaft (8) is In thehorizontal position and measure the torque required torotate pinion (8) Record this measurement.10 Tighten adjustment ring (15) while turning bevel gear untilthere is zero backlash11 Loosen adjustment ring (15) to the nearest lock position(maximum of one lug movement).12. Tighten adjustment ring (2) until the torque required torotate 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 adjustmentring (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) untillock 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) andtighten adjustment ring (15) the same amount.17 If backlash is not enough, loosen adjustment ring (15) andtighten adjustment ring (2) the same amount.NOTE The differential preload will be kept only if oneadjustment ring is loosened and the other adjustment ringis 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 beenmade, 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 andoil on the teeth of ring gear (12)b Turn pinion (8) In both directions.c The correct area of tooth contact is located equally onboth sides and starts near the inside end of the teeth of ringgear (12) See Illustration B for an example of the correct areaof 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 7c. Do Steps 15 through 19 again.21 If the marks made on the teeth of ring gear (12) look likethe 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 7c. Do Steps 15 through 19 again.NOTE: Always make sure the backlash adjustment iscorrect before an adjustment is made to the area of toothcontact Several adjustments to the backlash and toothcontact may be necessary to get the correct adjustments.22. After adjustments are made, remove the paint from thegears.23 Install locks and bolts on caps (1) and (14).1-49
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