Mr Patrick -
Several ideas for you....
• IMHO .050" axial play is not excessive, and may have steered you from measuring the REALLY important dimension... namely the diameter of the end journals of the layshaft. The bronze layshaft bushes are worthless. They absorb grit, which then act like grinding stones reducing the journal diameter (basically grinding it down as you ride).
• I believe that journal is supposed to be 11/16 (.6875) inches diameter on both ends. It's not unusual for pre-unit layshafts to loose .030" or more using old plain bronze bushes. That goes on to affect the shifting.
• If there is any way possible, you should convert your layshaft bearings (both ends) to the needle roller type used from ~1963 on. If your journal diameter is reduced, you may have to find a layshaft from a 1963-65 model (such as in your photo) that still used the speedo drive off the layshaft end.
• Conversion will require that you fit the shaft with the 0.66" long journals that you show in your photo. That's the difference in those 2 shafts in your photo:
pre-unit plain bush vs. unit construction with Torrington needle roller bearing journal lengths. Once you have the shorter layshaft, conversion is easy. You simply tap the needle rollers into place with THIS TOOL
. No machining of the cases is required.
• Let me urge you to further reduce your gearbox wear by converting over to 90W or 80/90W gear oil
. Your Manual
may suggest 50W engine oil, but that is so far outdated as to be laughable. OTOH you don't need expensive synthetic, just plain old EP gear oil will do fine. Synthetic is simply too expensive to change every 6 months like you should be doing.
• If you have evidence of a lot of water collecting in the outer g/b cover then you may want to consider drilling an extra drain hole as I did on my 1966...
This allows all the water to drain out during a regular oil change. Without the lower hole the water is simply trapped.
Hope this helps! :bigt