V50 - new gearbox breather, now won't shift

[jamesfjamesf]

I really thought I was done asking questions now that the bike is all assembled, but when I attempted to roll the bike off the workstand using the clutch as a brake while in gear, I discovered it wouldn't shift into gear. Not up nor down. The lever and linkage move, and there is upwards and downwards spring pressure, i.e. it returns to center, it just won't shift into gear. Something is hitting something becasue there is a metallic clack seemingly from the gearbox, the linkage isn't causing it. It's very much like the gears aren't spinning and allowing the dogs to engage, but neither a running engine nor rolling the bike changes anything.

I replaced the stock breather with the recommended banjo bolt and a banjo fitting:

https://www.thisoldtractor.com/moto_guzzi_small_blocks_transmission_breather.html

I didn't move anything during the swap. It's the only thing I touched on the gearbox, other than separating it from the engine. I'm at a loss. Could the breather swap be doing this or is it a red herring?

thanks,
jim

[n3303j]

Take out the breather bolt and see if everything works. Stuff is close to the case in some parts of the transmission. The replacememt breather bolt probably tangled with something moveable.

[Antietam Classic Cycle]

I really thought I was done asking questions now that the bike is all assembled, but when I attempted to roll the bike off the workstand using the clutch as a brake while in gear, I discovered it wouldn't shift into gear. Not up nor down. The lever and linkage move, and there is upwards and downwards spring pressure, i.e. it returns to center, it just won't shift into gear. Something is hitting something becasue there is a metallic clack seemingly from the gearbox, the linkage isn't causing it. It's very much like the gears aren't spinning and allowing the dogs to engage, but neither a running engine nor rolling the bike changes anything.

I replaced the stock breather with the recommended banjo bolt and a banjo fitting:

https://www.thisoldtractor.com/moto_guzzi_small_blocks_transmission_breather.html

I didn't move anything during the swap. It's the only thing I touched on the gearbox, other than separating it from the engine. I'm at a loss. Could the breather swap be doing this or is it a red herring?

thanks,
jim

You didn't lose the (detent plunger) spring did you? That could cause it.

[jamesfjamesf]

You didn't lose the (detent plunger) spring did you? That could cause it.

No, I clearly remember having a very hard time compressing the spring long enough to get the threads started. But how would that cause the shift drum not to rotate? I'd assume the shift drum would rotate quite freely without the spring & plunger to index it.

jim

[Antietam Classic Cycle]

No, I clearly remember having a very hard time compressing the spring long enough to get the threads started. But how would that cause the shift drum not to rotate? I'd assume the shift drum would rotate quite freely without the spring & plunger to index it.

jim

Just throwing it out there.

[jamesfjamesf]

Just throwing it out there.

Ok, I thought maybe I was misunderstanding the function of the spring & plunger. Anyway, turns out the new bolt I received is significantly longer than the breather that came out. I thought I measured it before installing. Backing it off a buncha turns fixed the issue so I need to trim the bolt. Stay off drugs, kids.

jim

[Chuck in Indiana]

Failing memory, thinks you dodged a bullet. That detent locates (from memory again) a bearing? Lose that location, and you're in a heap of trouble, boy. 

[Antietam Classic Cycle]

Failing memory, thinks you dodged a bullet. That detent locates (from memory again) a bearing? Lose that location, and you're in a heap of trouble, boy. 

You're thinking of the oil pressure sender, Chuck. That locates a cam bearing.

[Chuck in Indiana]

You're thinking of the oil pressure sender, Chuck. That locates a cam bearing.

Ahh, right as usual, Charlie.  It's been several years since I have actually *worked* on a small block, and I'm old. :)