TM 10-3930-671-24 C. Pinion Gear Shimming 1 - No Replacement of Gears or Housings If the ring and pinion gear or the transmission case  was not   replaced,   use    original    shim    pack    thickness    and proceed to: D. Pinion Gear Installation PINION INNER BEARING SHIM PACK NEW THICKNESS SELECTION If ring and pinion gears or transmission case replaced: 2 - Transmission Housing Replaced If   the   transmission   case   was   replaced,   the   following procedure must be used to set the correct ring gear and pinion contact: On the new transmission case, a dimension for the case bore depth will be stamped on the location shown above. SHIM PACK THICKNESS CALCULATIONS The  following  conditions  are  used  to  calculate  the  shim pack thickness to be installed. A = Nominal  pinion  mounting  distance  5.900  in. (149.860 mm). B = Typical  pinion   mounting   distance   (which   is etched   on   the   outer   diameter   of   the   ring gear). C = Case bore depth (stamped on the case). D = Nominal shim pack of .034 in. (0.86 mm) E = Final   shim   pack   to   be   installed   under   the inner    pinion    bearing    cup    to    position    the pinion shaft. NOTE If original shim pack is lost or must be replaced, use  D  Nominal  shim  pack  thickness  of  .034  in. (0.86 mm). Check new shim pack dimension by measuring  thickness.  Substitute  new   thickness for original (old) thickness where shown. The   following   examples   show   sample   calculations   for determining   the   shim   pack   thickness   to   be   installed under the pinion inner bearing: 1. If the case bore depth (stamped on case) has a "+" (plus) sign, add (C) to the nominal shim pack (D). 2. If the case bore depth (stamped on case) has a "-"  (minus)  sign,  subtract  (C)  from  the  nominal shim pack (D). 3. If    the    nominal    mounting    distance    5.900    in. (149.860    mm)    is    smaller    than    the    mounting distance  etched  on  the  ring  gear,  subtract  (A) 5.900   in.   (149.860   mm)   from   (B)   the   etched mounting   distance.   Subtract   this   answer   from the  answer  of  ’D"  and  ’C".  See  examples  1  and 2. 4. If the mounting distance etched on the ring gear is smaller than the nominal mounting dimension 5.900   in.   (149.860   mm),   subtract   the   etched mounting distance from 5.900 in. (149.860 mm). This  difference  is  added  to  the  answer  of  "D"  and  "C". See examples 3 and 4 above. F-368