Here are my machine shop plans. I left the details up to the shop, which decided to use wire EDM (Electrical Discharge Machining). I think that grinding could also be used. I can email you a Word or PDF version which shows things actual size, and lined up properly. If you want the file (it is less than 800 KB), send me a note: TGLEONE AT GMAIL DOT COM
Modification sequence for Gear #1 Note: This gear must be modified before Gear #2
Original appearance of Gear #1 (side and edge views): 
Modification: Locate on I.D. (splines), and remove all material greater than 1.25 inch diameter (+/- 0.005 inch). Accurately measure new O.D. "A" to use for Gear #2. Chamfer one edge of O.D. if necessary for pressing and/or welding. [My shop decided not to chamfer this one.]
Gear #1 after modification (side and edge views):
Modification sequence for Gear #2
Note: This gear must be modified after Gear #1
Original appearance of Gear #2 (side and edge views): 
Modification: Remove all material to the right of line "Y-Y". Locate on Surface "X" (or on gear teeth), and make a concentric hole, starting at "Y-Y" and going through center of gear. Final diameter of the hole should be 1.4 to 2.4 thousands of an inch less than O.D. "A" of Gear #1, so that Gear #2 becomes a press fit onto Gear #1. Then remove material to left of line "Z-Z" and make that surface approximately flush with side of gear. Chamfer one edge of I.D. if necessary for pressing and/or welding. [My shop decided not to chamfer this one.] Avoid overheating gear, to preserve its heat treatment.
Gear #1 after modification (side and edge views):
Modification sequence for Gear #3
Note: This gear must be modified before Gear #4
Original appearance of Gear #3 (side and edge views): 
Modification: Locate on I.D., and remove material from O.D. until gear teeth are barely removed (approximately 2.85 inch diameter). Accurately measure new O.D. "B" to use for Gear #4. Chamfer one edge of O.D. if necessary for pressing and/or welding. [My shop decided not to chamfer this one.]
Gear #3 after modification (side and edge views):
Modification sequence for Gear #4
Note: This gear must be modified after Gear #3
Original appearance of Gear #4 (side and edge views): 
Modification: Locate on I.D. at right end (inside synchro cone, not inside gear teeth), and make a hole starting from left end. This may require two steps to avoid separating gear teeth from original I.D. before hole is finished. Final diameter of the hole should be 1.9 to 2.9 thousands of an inch less than O.D. "B" of Gear #3, so that Gear #4 becomes a press fit onto Gear #3. Then remove material to right of line "J-J" and make that surface approximately flush with side of gear. Chamfer one edge of I.D. if necessary for pressing and/or welding. [My shop decided to chamfer this one about 1/8th inch to get weld penetration.] Avoid overheating gear, to preserve its heat treatment.
Gear #4 after modification (side and edge views):
Pressing and welding [or silver soldering] gears together
Press Gear #2 over Gear #1, so that one edge of Gear #2 is 10 to 20 thousandths of an inch from one edge of Gear #2. [My shop heated the large piece and cooled the small one, rather than just pressing together. The weld is at a shoulder so no chamfer is necessary for weld penetration on this one.] Then weld two gears together at opposite edge. Please pre-heat before welding, and weld a little at a time to avoid ruining heat treatment of gear teeth. If I ever do this again, I might silver solder them together instead of welding, to avoid possible damage to the heat treatment. In hindsight, I think that the welding also caused distortion of the gears (see "Durability Failure" above). 
Press Gear #4 over Gear #3, so that one edge of Gear #4 is flush with synchro edge of Gear #3. [My shop heated the large piece and cooled the small one, rather than just pressing together.] Then weld two gears together at opposite edge. Please pre-heat before welding, and weld a little at a time to avoid ruining heat treatment of gear teeth. If I ever do this again, I might silver solder them together instead of welding, to avoid possible damage to the heat treatment. In hindsight, I think that the welding also caused distortion of the gears (see "Durability Failure" above).
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- Tom Leone TGLEONE AT GMAIL DOT COM
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