G/box mainshaft/output shaft bush

breganzane said:
Can I ask a silly question?  Did you spin the rear wheel with the rear caliper removed but the chain still connected?  Non-returning master cylinders are pretty common, causing pad drag.  It is not at all uncommon for the spline to be hard to turn by hand due to seal drag, but maybe what you observed was pad drag?  Just a thought.
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Rob, did you see this post?  If you did not test for it then perhaps it is possible that once you disconnected the chain the actual problem was gone but you had already in mind the fault was with the gearbox and once you found the output shaft difficult to turn (which it always is in my experience) you had your smoking gun?  This would be a classic case of confirmation bias.  Possible?  Or did you eliminate that?
 
Hi Steve, first thing I did was removed the wheel and check the bearings etc. The problem still existed when I pulled the chain through and turning the sprocket by hand.
Definitely something going on with either the output shaft or layshaft. The mainshaft turned as it should once I removed the primary chains.
Bear in mind that it only had 3000 kays on new bearings. The gear changing was normal. If I hadn't of lubed the chain I'd never notice.
Been turning the rear wheel lubing laverda chains for 40 years now so I know when something doesn't feel right.
The other weird thing was when I cracked the case joint it started turning as it should so I'm thinking maybe the output bearing may have moved in the cases due to sloppy bush/ unsupported shaft therefore binding between the outer and inner race of the bearing.
Can understand you point regarding "confirmation bias" but it really didn't feel right on the counter shaft sprocket.
Will strip the mainshaft and check for trueness next.
 
Or is it possible one or more of the new bearings was fitted out of true?
 
Grant said:
Or is it possible one or more of the new bearings was fitted out of true?
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Highly unlikely.
Remember it went back together just as it should and has been fine up until the last couple of hundred kays as it wasn't like that on the previous lubing the chain exercise.
Say for instance there was too much clearance on the mainshaft and bush. there is only the mating face between the cases and the bearing holding the output shaft in place.
Under hard acceleration whats stopping the output shaft from twisting if it isn't supported at the main shaft end? The main bearing would be working skew whiff and the main shaft wouldn't be true to the bush. Also might explain the reason it freed up once the cases were cracked apart.
I've spoken to my engineering mate in Perth and he'll replace the bushes and dress the main shaft if needed. Hopefully Wolfgang has the bushes available.

Are the countshaft splines repairable?
 
motoddrob said:
Say for instance there was too much clearance on the mainshaft and bush. there is only the mating face between the cases and the bearing holding the output shaft in place. 
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+1.  i agree.  the outer bearing race is gunna try to hold on to that sleeve gear when it wants to misalign.
fig169-Lav180-cr2.jpg

and i suggest the misalignment load sharing between the bearing outer race and the sleeve gear inner bushes will also be dependent on the internal clearance of the bearing, as well as the running clearance between the inner bushes and the mainshaft ??
i'm guessing the bearing is the C3 internal clearance?

anyhow, all academic i guess.
probably just need to assemble it all back to how it was a decade ago, when we were standing around and admiring ya Motodd at the Bello rally of '04.
would luuv to drool over it again, as i've heard from many, that it looks even better than the photos!
all the best.  we know you'll get it back on the road, soon enough.  one step at a time.    (thumbup)
  cheers,  Mark
 
Ok, if it rotated freely shortly after building then maybe the extra power it has now has bent/twisted the shaft?
I assume you ran it in gently at first and sooner or later gave it the berries.
Did you say you had another gearset to hand?
 
OK, I think I must have caught some kind of disease. I now can't stop looking at that Zane triple and am starting to lust after a Benelli TNT. Must be Triple Pox or something.  :o
 
It would need a hell of a lot of clearance in the sleeve bush to let the gear get out of alignment.

If the mainshaft turned OK drom the clutch side with the primary chain off, then the sleeve gear isn't binding. I reckon it's the outer (ball) bearing on the output shaft. Maybe the bearing doesn't have enough internal clearance. Is it a C3?

It could also be a bearing on the layshaft, which is disengaged from the main shaft (but not the sleeve gear) when in neutral, but that seems less likely. If the layshaft was binding, you'd have felt a wee bit of backlash when turning the sprocket by hand (tooth clearance between the 5th gear and its mate on the layshaft).
 
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