TM 10-3930-671-24 E. Trial Wheel End Assembly For Ring & Pinion Gear Contact & Backlash Check (Pinion Gear & Differential Installed) 1. Position the differential assembly in transmission case. 2. Assemble    the    wheel    end    housings    on    the transmission   case   as   marked   at   disassembly. Align with differential bearings. 3. Install the wheel end housing bolts and washers. Tighten  bolts  to  torque  spec;  80-88  lb-ft.  (108- 119 N•m). 4.    Check ring and pinion gear backlash. Open the inspection  cover  on  the  top  of  the  differential case Set up and position a dial indicatoron a ring gear   tooth   to   check   the   ring   gear   to   pinion backlash.   Hold   pinion,   move   ring   gear   within backlash free play range several times. Backlash should   be   measured   at   3   places   minimum around the ring gear (rotate ring gear). The backlash must be as indicated on the outer diameter of the ring gear as "BL". To  set  the  correct  backlash,  shims  behind  the  tapered bearings  on  the  wheel  end  housings  are  removed  from one side and added to the other. Remove the wheel end housings,  remove  bearings  and  move  shims.  Repeat above assembly and checking procedure. 5.    Check ring and pinion gear tooth bearing contact pattern. •  Also  refer  to  Spiral  Bevel  and  Hypoid  Tooth  Bearing Contact Chart, Section 7.0. To   check   the   ring   gear   and   pinion   for   proper   tooth contact pattern (correct position). apply a coating of gear checking compound. e.g., red lead. to the ring gear teeth Rotate  the  ring  and  pinion  gears  through  a  minimum  of one  revolution  Apply  a  load  (hold  by  hand)  to  the  gears as  they  are  turned  When  the  ring  gear   is   turned   the compound is squeezed away by the contact action at the teeth,  leaving  bare  area  that  are  the  exact  shape.  size and area of the tooth contact pattern. Check the tooth contact area on the drive (convex) side of the ring gear teeth See figure above for typical correct tooth contact pattern If the tooth contact is not as shown, recheck the pinion mounting procedure and also the ring and pinion backlash reading. Disassemble the parts, add or remove, or move shims as needed to adjust pin ion or ring gear position and backlash and recheck. IMPORTANT-   Each   time   the   ring   gear   or   pinion   is moved,  the  backlash  and  the  bearing  preloads  must  be checked and reset as needed. F-370