ambo 4 speed rebuild

[harrytief]

I am doing my first 4 speed rebuild. I've read what I can find online but no mention of the reluctance the shift drum has to being rotated when installed in the transmission case and hooked up to the shift forks. With the case open, all shafts in and forks installed, I am trying to align the drum so that it sits with its neutral knob facing the detent plunger port ready for the shift pawls and cam plate install. The d$#^ shift drum is almost impossible to rotate and does so only when I lift the shift forks carefully. Clearly, the ends of the forks are dragging in their tracks on the shift drum. I've tried various shim combinations on either end of the drum with no improvement. All case bearings are new and all shafts spin freely when shift forks are out of the box. Gears and neutral engage when I shift with the forks and drum removed from the box.
Is it common to have the ends of the forks drag so much with the install as described? Is there some problem I am overlooking? Will installing the back cover (thanks Patrick) and and clutch hub cure any alignment issue...wishful thinking?
The 5 speed seemed so much easier
Ideas?
Harry

[guzzisteve]

When things are tightened up it all lines up. Don't do it dry, make sure it all has lube on it.

[pehayes]

Difficult to move a Guzzi transmission when the internals are static.  Works a LOT better when things are rotating internally.  Even after assembly, if you bench test the shifting make sure someone helps by spinning either the input or output shaft while you manipulate the shifter.  I built this jig for my vise so that I could do the bench testing without additional helping hands.

Patrick Hayes
Fremont CA

[harrytief]

OK. So I buttoned it up and yes ,Patrick, it does shift better but now as a two speed. I've got gear engagement on either side of a neutral so I may only have 1rst and 2nd. I don't feel any additional engagement when I try to upshift past "second". The John Schwartz drawing I found on Greg Bender's site suggests that the shift drum and shift pawls need to be in a precise alignment
or the two speed result occurs. I set it up as per John's diagram but the pawls may have moved when I installed the shift arm/spring. I'll look tonight. Any other thoughts?
Harry

[Antietam Classic Cycle]

OK. So I buttoned it up and yes ,Patrick, it does shift better but now as a two speed. I've got gear engagement on either side of a neutral so I may only have 1rst and 2nd. I don't feel any additional engagement when I try to upshift past "second". The John Schwartz drawing I found on Greg Bender's site suggests that the shift drum and shift pawls need to be in a precise alignment
or the two speed result occurs. I set it up as per John's diagram but the pawls may have moved when I installed the shift arm/spring. I'll look tonight. Any other thoughts?
Harry

Sounds like a definite alignment issue. You're basically putting the transmission in third gear before you assemble it.