well, I am still having trouble - the crank arm will not stay on
i did manage to lengthen the interval between failure though.
So, i experimented with simply removing the 3mm spacer, to get more of the pedal arm over the drive side spindle. It was obvious that this would not work because the spindle was now about 1/2mm too long - with the crank arm on as far as it would go, there was a tiny gap. The spindle would be free to slide back and forth, and the with the chain rings moving in and out by 1/2mm, the shifting would not be very good.
I fact, one of the first signs that the arm is coming off is that i can no longer shift to the large chain ring - as the pedal arm loosens and begins to slip off, the chain rings move outboard, and the large ring gets beyond the limit stop.
anyway, i next experimented with a home-made spacer of about 1/2mm, made from a takeout food container, installed without the 3mm spacer. This seemed to work better - certainly I got the pedal arm on to the spindle much further. It was tight and shifting was good.
I then found these delrin spacers made for shimano BB's by Wheels Manufacturing
https://wheelsmfg.com/products/botto...-brackets.html
they have a 1mm and a 1/2mm spacer.
I installed a 1mm spacer in place of the 3mm spacer.
I also bought a new part
#4 , and a new crank arm
on closer inspection of the crank arm and spindle it seems they are fine, so i did not use the new crank arm yet.
everything goes on fine - i get the arm seated well on to the spindle. Shifting is good.
but after say 100-150miles, i notice the shifting problem - it gets hard, then impossible, to shift to the large chain ring, as the arm begins to slip off the spindle and the whole crank is free to move side-to-side a bit.
I carry the tools, and can fix it on my ride - but it sure is a pain.
I am thinking of trying the new crank arm.