Trans Prob Solved -Shift drum bracket installed upside down

sdaigle240 · Post by **sdaigle240** » Tue Aug 04, 2015 8:49 am

Hello h305,
Trying to figure out whats wrong with the shifter/transmission on a 65 cb77. bikes a bit of a basket case with unknown history. runs, drives and stops... it shifts but its pretty "jammed up"

It was acting a bit like it had a broken or absent shifter return spring but its there and good. i would have to manually return the shifter to center to be able to get it to click again. so i removed the clutch assembly, got a feel for the shifter linkage then put the cover back on to see what happens. for the only time, it appeared to go through the gears, and then bam, it "jammed" so i took the case back off to see what said jam was. What i noticed was how poorly the gear shift arm and gear shift drum interact. it appears the drum does not fully toggle over when the arm is pushed. now ill say im pretty sure if i yank away at the shifter while rolling the back wheel it will "free up" again.

Below is a picture of the drum with the arm pushed all the way one way and released and the other photo is pushed the other way and released. you can see im kind of stuck in limbo as it hasnt moved enough to allow for another shift. occasionally the assembly seems to work right allowing for me to get in a few shifts but nine times out of ten its as described.

Pushed right and released

Pushed left and released

just an up close with the arm pulled away from the case

any and all assistance is greatly appreciated!
-Steve

G-Man · Post by **G-Man** » Tue Aug 04, 2015 11:04 am

Is the shaft straight and free in the case? it might have taken a hit on the gear shift lever and bent the shaft.

Does the drum rotate freely if you strip off the shifter mechanism?

G

Tim Miller · Post by **Tim Miller** » Tue Aug 04, 2015 11:56 am

Looks like drum plate is on upside down. If so it will drag on detent mechanism.

Tim

G-Man · Post by **G-Man** » Tue Aug 04, 2015 2:31 pm

Good spot!

G

Tim Miller wrote:Looks like drum plate is on upside down. If so it will drag on detent mechanism.

Tim

sdaigle240 · Post by **sdaigle240** » Tue Aug 04, 2015 4:06 pm

G-Man wrote:Is the shaft straight and free in the case? it might have taken a hit on the gear shift lever and bent the shaft.

Does the drum rotate freely if you strip off the shifter mechanism?

G

Thanks for the reply G

the shift shaft has been rewelded at some point. it broke internal to the case but is pretty darn straight considering.

with the mechanism pulled away I was using a screw driver to try and move the drum with no more luck than the shifter mechanism. again, if i get a little rough with the shifter and roll the wheel backa nd forth i can usually free things up temporarily. it shifted gloriously up all gears when i put the cover back on without the clutch stuff. that lasted a few clicks before it jams up and seems to only go up one and then back down one.

sdaigle240 · Post by **sdaigle240** » Tue Aug 04, 2015 4:07 pm

Tim Miller wrote:Looks like drum plate is on upside down. If so it will drag on detent mechanism.

Tim

you rock, tim. i will investigate!

sdaigle240 · Post by **sdaigle240** » Fri Aug 07, 2015 5:32 pm

The bracket was indeed installed upside down but I can't for the life of me figure out how you would get the bracket on correctly without doing it during case assembly. The internal shift fork appears to be bolted to the drum so I cannot pull the drum far enough out to slip the bracket into the collar. If it is that it needs to be installed during assembly of the case do you think I could just cut the bracket in half and install it as two pieces? Seems reasonable given its function.