Hey things are ago again! I have put a little time in to get this other in better shape 3.5 Briggs on my bike too.
I will want to tap 1/4 - 20 threads into a 5/8 jackshaft to aid clutch to stay put. If there was enough room I'd also have a split collar, but it won't fit under existing cover.
I did in the past put threads in the end of the Briggs 3hp crankshaft while it was on the engine. I guess it was dumb luck. Actually I chickened out for a moment when the HF tap which only was probably good for clay, but not mid grade carbon steel failed.
Lucky I found high quality drill, tap, die, and Helicoil (for other projects) parts at a specialty shop in San Jose that will sell individual parts to the public.
Most important I found out what the occasional loud noise that emanated from near the jack-shafts on my bike were. The noise got a good resonance with the cover, but did not make it easy to find until seeing the jack-shaft worn spot under the areas of the 4 pillow bearings.
They are just the width of the bearings. So you know the bearing inner surface was not tight on the jack-shaft.
In removing bearings necessary to reconfigure for new used engine, I also saw on the outside of the outer bearing surface scrapes. Seems I am going to put new bearings in and new jackshafts, but use also Loctite 39150 High Temperature Bearing Mount Stick.
There are bearing by Timken that if I were to buy them, which well I am not going to afford $40 or more each, some of these have a way of tightening on to shaft. Two set screws do not exactly touch the shaft, but (ha for protection) put pressure on a sleeve that then connects all together.
Trademark Shaft Guard Technology is the expensive stuff.
Instead on the cheap I spend $14 on some kind of glue high temp that supposed to keep stuff together. I've hear of hammer peening as well to loose fitting pillows or something to make sure it is the ball bearing that roll.
The idea I heard is if the bearing are too loose fit, they will spin on the shaft and or the pillow bearing mount and create metal dust. The dust then gets into the bearing. The bearings heat due to the foreign matter, and you know the rest.
In the future I will just replace the bearings even before I notice a problem after enough miles put on them, just so for preventative maintenance. I also know weather gets to the bearings and the places I ride are not friendly to them either. Going through streams and mud is fun though!
Just checked, I got 2 and a 1/2 years riding on the bearings now problem before this intermittent scraping started a year ago, but did not pin it down and find out exactly til now.