Before disassembly, remove the inspection cover. This  will  allow  you  to  observe  transmission  action. Shift the transmission into each gear, and, at the same time,  rotate  the  input  shaft  while  inspecting  the conditions of the gears and synchronizers. The basic disassembly procedures are as follows: 1. Unbolt and remove the rear extension housing. It may be necessary to tap the housing off with a soft face mallet or bronze hammer. 2. Unbolt and remove the front extension housing and any snap rings. 3. Carefully pry the input shaft and gear forward far enough to free the main shaft. 4.  Using  a  brass  driftpin,  push  the  reverse  idler shaft and countershaft out of the transmission case. 5.   Remove   the   input   shaft   and   output   shaft assemblies. Slide the output shaft and gears out of  the  back  of  the  transmission  as  a  unit.  Be careful not to damage any of the gears. After  the  transmission  is  disassembled,  clean  all the  parts  thoroughly  and  individually.  Clean  all  the parts  of  hardened  oil,  lacquer  deposits,  and  dirt.  Pay particular attention to the small holes in the gears and to  the  shifter  ball  bores  in  the  shifter  shaft  housing. Remove all gasket material using a putty knife or other suitable  tool.  Ensure  that  the  metal  surfaces  are  not gouged   or   scratched.   Also,   clean   the   transmission bearings   and   blow-dry   them   using   low-pressure compressed air. NOTE Always use protective eyewear when you are blowing the bearing dry with compressed air.  Do  NOT  allow  the  bearing  to  spin.  Air pressure  can  make  the  bearing  spin  at tremendously  high  rpm,  possibly  causing  the bearing to explode and fly apart. After   all   parts   of   the   transmission   have   been cleaned,   inspect   everything   closely   to   determine whether they can be reused or have to be replaced. The wear or damage to some of the parts will be evident to the  eye.  If  brass-colored  particles  are  found,  one  or more  of  the  synchronizers  or  thrust  washers  are damaged.  These  are  normally  the  only  transmission parts  made  of  this  material.  If  iron  chips  are  found, main drive gears are probably damaged. To check for damage or wear on other parts, it may be necessary to use  measuring  tools  and  gauges  to  determine  their condition. Any  worn  or  damaged  parts  in  the  transmission must be replaced. This is why your inspection is very critical. If any trouble is NOT corrected, the transmis- sion  overhaul  may  fail.  You  would  have  to  complete the  job  a  second  time,  wasting  man-hours  and materials,  as  well  as  unnecessary  equipment  down- time. Always  replace  all  gaskets  and  seals  in  the transmission. Even though the seal or gasket may have not  been  leaking  before  disassembly,  it  may  start  to leak after assembly. When  replacing  a  main  shaft  gear  either  due  to wear or damage, you should also replace the matching gear on the countershaft. If a new gear is meshed with an old gear, transmission gear noise will occur. If new bolts are needed, make sure it is the correct thread type and length. Some transmission use metric bolts.   Remember   mixing   threads   will   cause   part damage. All  parts  must  be  lightly  coated  with  a  medium- grade  lubricating  oil.  This  is  done  immediately  after the  inspection  or  repair.  Oiling  the  parts  give  them  a necessary  rust-preventive  coating  and  facilitates  the assembly  process. After  obtaining  new  parts  to  replace  the  worn  or damaged   parts,   you   are   ready   for   transmission assembly.  To  assemble  the  transmission,  use  the reverse  order  of  disassembly.  Again  refer  to  the  service manual   for   exact   directions,   as   well   as   proper clearances  and  wear  limits  of  the  parts.  The  service manual   will   have   an   exploded   view   of   the   trans- mission.  It  will  show  how  each  part  is  located  in relation  to  the  others.  Step-by-step  direction  will accompany  the  illustrations. Certain  key  areas  of  the  transmission  should  be given extra attention during assembly. One area is the needle bearings. To hold the needle bearings into the countershaft or other shafts, you coat the bearings with HEAVY GREASE. The grease will hold the bearing in place as you slide the countershaft into the gears. Also, measure  the  end  play  or  clearance  of  the  gears  and synchronizers  and  the  countershaft  and  case  as directed by the service manual. Before  installing,  ensure  the  transmission  shifts properly. This will save you from having to remove the transmission if there is still problems. Also, since the transmission  is  already  out,  this  is  an  ideal  time  to inspect the condition of the clutch. 4-24