Gearbox Stuck - The last straw?

[Laverda Dave]

OK, thanks.

I'll try that once I get the clutch off. Trying to find someone with a castellated socket; I'm here with 4 spanners, a screwdriver and a vise grip! 

You need the correct tool to remove the clutch centre nut, it is held on really tight. You'll need to probably use a torque ratchet to get the oomph needed to loosen it and make sure you have bent the tabs back on the lock washer before attempting to undo the nut (and replace the tab washer, not worth the risk of using the old one).

[SeanFD]

I've got the clutch off now - had to hire an impact wrench to remove the centre nut!

The only thing that looked amiss in the selector setup was the actuator to the end of the gear shaft; it seemed to have moved outwards and was not meshing with the pins on the drum centre.

With everything off, it looks to me as if the selector drum, when the gearbox is in "neutral" that the hole to align with the drum centre is rotated too far anti-clockwise?

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I can move the drum only about 30º and there is a positive and solid click each time it moves - I replaced the bits on the end of the drum to allow me to rotate it. It will only go anti-clockwise and I've no way of telling if different gears are actually being selected.

What next? The only thing I can think, is reassemble and see f it works!

Not feeling too hopeful here! 

[K2-K6]

You should be able to feel the difference in ratio by turning the rear wheel, it will rotate the centre (clutch) shaft at different speed.

1st would spin that shaft fastest, 6th the slowest.

[SeanFD]

It doesn't seem to change; at least not noticeably.

[K2-K6]

Have you got the shift mech reassembled  ?

If so, with a mark on the outer face to show movement, it should "index" around each time the lever is used. Then obviously return to original position by going back down the ratios.

[SeanFD]

Which direction does it move when going up through the gears?

I can only move things anticlockwise, 4-5 "clicks".

That reference hole on the drum doesn't move at all.

I have 2 settings:
1.  Rear wheel and shaft turn together - each one turns the other in both directions. As I said earlier, it doesn't feel like it gets easier/harder or /faster/slower as I move through those 5 clicks.

2.  Wheel and shaft are separated; each can turn independently.

[Bryanj]

It is very difficult to diagnose long distance but from what you are describing i think something is assembled wrong, at leasr you dont have to take any top end stuff off to check

[SeanFD]

She ran OK, with noting feeling wrong for a short while, so I would think it is more like something has come adrift or broken.

Anyway, I'll not be taking anything further for now; I have to go home and prepare to finish my odyssey - I still haven't heard if Iran is issuing visas again yet.

So just when I thought I could jump into the water, looks like I'll be sitting on the bank for another while; probably be Xmas before I'm back to try and finish the job.

My general philosophy: It'll be all right in the end. If it's not all right ....!

[SeanFD]

OK, so I went out this morning just to reassemble everything and put it away, but of course I couldn't just do that, could I.

I got this video once things were back together.

https://youtube.com/shorts/3N8Lcwp9agM?feature=share

It looks to me like the selector drum has rotated because that locator pin is too far anticlockwise when compared to the only other shot I could find of it on-line.

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With mine the way it is, the actuator has only two lugs to act on.

[Bryanj]

I rhink it can only do that with the gearshafts out

[SeanFD]

when I get home, I think I have more pics of the assembly. It'll be interesting to see where it was when I put it together.

[SeanFD]

Greetings,

So I've finished my wee RTW jaunt, with a rapid blast through Saudi, Kuwait, Iraq, Turkey, Greece, Italy and France.

(belfast2belfastbybike.com if anyone is interested)

Now with Xmas coming, it's time to think about the annual visit to the old homestead, where my nemesis awaits - deep breath!

To remind anyone who has memory akin to my own, I rebuilt it, rode it for a few kms. Set out on a longer ride and after less than 1 km it wouldn't shift out of 1st gear. Examination and adjustment of everything reasonably accessible - clutch, gear shift mechanism, gear change pedal ... resolved nothing. At the end a comparison of before and after photos suggested that the gear selector drum has rotated!

So the decision was put everything back in place and leave it till .... well, now.

The plan is to remove the engine and take the lower case off to see if I can see anything untoward. From memory (very fallible) and the parts fiche, it seems that the only parts I will need for this is a new sump gasket - assuming all is well internally.

Have I got this right? Has anyone any tips to make the task easier?

Stay well all.

[Laverda Dave]

You'll need some hondabond (or similar but not instant gasket) to rejoin the cases along with plenty of clean rags to prevent any of the old gasket from dropping into the engine as you scrape it off.
If it were me and I was disturbing the final drive oil seal I would be replacing that as well, the last thing you want is weeping oil when you put it all back together. Take the lower case off slowly in case any crankshaft bearing shells stick to the crank, don't want to mix those up!
Good luck🤞

[Dolomite_]

I've just had the same issue, after a 30 mile ride this morning. On the last mile when pulling away from traffic lights it wouldnt go from 1st into 2nd.

Ive done 700+ faultless miles since I rebuilt the engine in the summer of 2024.

There is a sound coming from the gearbox when I put it in 1st, hold the clutch in and spin the wheel. I cant remember if that was there before and is normal. There seems to be too much resistance when its in 1st and I spin the wheel with the clutch held in.

I'm worried that its the worse case and something has gone wrong internally but I'll take the same steps as you and take a look at the gear selector mechanism behind the clutch drum.

Hopefully you update the thread with some good news!

[McCabe-Thiele (Ted)]

Just trying to think outside the box, could this be caused by the retainig clip coming off the gear selector fork?