Hi Folks,
I’ve been troubleshooting an occasional missed gear change on a 71 bonnie. Generally on the upshift to 2nd/3rd.
I "feel" from riding this summer that the gearbox "overshifts" when it ends up in neutral on the occasional upshift, and I push down to get back to the gear I wanted in the first place. (seems to be similar to the problem indicated in service bulleting 8-59, with too much movement)

Discussing previously with Bruce/Hermit, he mentioned he had a similar problem that went away with a new gear shift quadrant. His problem was when down shifting the cam plate would not turn enough (incomplete shift). (the opposite of the service bulleting 8-59)
It should be noted there is another troubleshooting page that indicates filing away the quadrant instead of building it up in case of "improper upshifts" with too little movement as experienced by Bruce.

To try to understand the problem we attached degree wheels to the gearlever shaft and measured the movement on up- and down-shifts.
Bruce consistently got 19 degrees up-shift and 19 1/2 degrees down-shift on his good working gearbox. (on his 69 Bonnie)
I checked my degrees today. I did it a bit differently with the degree wheel on the outside of the bike but results should be the same. (Bruce did his on the inside of the dethatched gearbox cover)

My gear change movements, and return to centre, were also very repeatable, as were Bruces.
However, my downshifts were only 17 degrees movement, while my upshifts were 18.5 degrees of movement. See attached pictures.

Interesting that I have much less movement than Bruce on the “good” (downshift) side (17 vs 19 degrees) and slightly less on the “problem” (upshift) side (18.5 vs 19 degrees). The cover and quadrant are the same part numbers for '71 and '69...

I wonder if anyone else has measured their movement as we have done?

I will try a little bit of temporary plate on the upshift (bottom quadrant stop in the cover) to limit movement and see what it does next year when I ride again

[Linked Image]

Last edited by BrettF; 11/21/18 1:09 pm.

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Bikes: '69 T120 on average (1967 rolling frame and 1971 Bonnie engine) + '56 1/2 T110 on average (58 rolling frame - with 55 iron head engine) + 74 T150 Home model.