Clutch problems

I replaced mine due to excessive clutch movement, but found the mainshaft was worn too and needed replacing...
On a bike with allegedly 20k miles....

SteveA said:

Yes, and as noted the spacer locks over the circlip and the shims are for clutch drum to engine sprocket alignment, adjusted to ensure a straight run for your triplex chain.

And, sort of irrelevant after L.A.B.s post, but on the pre Commando short mainshaft gearbox on the shelf in my workshop I can see the phosphor bronze bush end maybe 1/16" in from the sleeve gear outer end.

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Thanks. At this point, with the play I have, I'd be surprised to find anything in there.
I'll pull the transmission today and find out though.

EstuaryBoy said:

I replaced mine due to excessive clutch movement, but found the mainshaft was worn too and needed replacing...
On a bike with allegedly 20k miles....

Click to expand...

Yeah, I'm hoping for the best.

JCP said:

Thanks. At this point, with the play I have, I'd be surprised to find anything in there.
I'll pull the transmission today and find out though.

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When you pull the transmission out check that it has a two piece roller bearing on the layshaft on the opposite end to the Kickstart
Check that the main shaft output bearing is tight in the case
Check for any cracks between the layshaft bearing housing and the output bearing housing
Always replace the circlip that the clutch spacer sits against
If you had a tab washer on the clutch retaining nut throw it away and just use loctite

Derek Wilson said:

If it is feeling like the lever has locked up, the cam that the cable fits into inside the transmission has likely slipped down out of position, quite common if the cable is disconnected and the clutch adjuster screw is removed to facilitate the use of the clutch spring compressor.

What do you have for a shop manual?

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The cable/ internal cam should have been fine (until, of course, the cable broke). And when I replaced the repaired cable the cam was moving like it should have.
When it happened, the response of the clutch plates wasn't exactly "locked". At the lever I had almost a "soft" resistant pull until a stop, but it's hard to explain. I have never quite felt it before (on any bike/ ever). Shutting the bike off half way through the ride I couldn't get the clutch plates to open enough to not have the bike jerk and stall when shifting from neutral. I had to ride it down a hill, the bike running and in neutral, and shift into first while I was rolling -- then ten miles later was when I started having more problems and then the cable broke.

JCP said:

The cable/ internal cam should have been fine (until, of course, the cable broke). And when I replaced the repaired cable the cam was moving like it should have.
When it happened, the response of the clutch plates wasn't exactly "locked". At the lever I had almost a "soft" resistant pull until a stop, but it's hard to explain. I have never quite felt it before (on any bike/ ever). Shutting the bike off half way through the ride I couldn't get the clutch plates to open enough to not have the bike jerk and stall when shifting from neutral. I had to ride it down a hill, the bike running and in neutral, and shift into first while I was rolling -- then ten miles later was when I started having more problems and then the cable broke.

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Was the clutch nut (57) loose?

If not, then the nut (26) at the opposite end of the mainshaft might be?

baz said:

When you pull the transmission out check that it has a two piece roller bearing on the layshaft on the opposite end to the Kickstart
Check that the main shaft output bearing is tight in the case
Check for any cracks between the layshaft bearing housing and the output bearing housing
Always replace the circlip that the clutch spacer sits against
If you had a tab washer on the clutch retaining nut throw it away and just use loctite

Click to expand...

Thanks/ will do.
Incidentally, I was in there just a few months ago, replacing the first gear bearing and the kickstart shaft, and shimming the play out...

It's a good thing I love this bike.

L.A.B. said:

Was the clutch nut (57) loose?

Andover Norton Parts Drawings - Genuine Andover Norton Factory Parts - Commando Parts

Andover Norton Parts are the only Norton spare parts in the market manufactured to original drawings, within the factory-approved tolerances, from the correct materials, and with the correct finish.

andover-norton.co.uk

If not, then the nut (26) at the opposite end of the mainshaft might be?

Andover Norton Parts Drawings - Genuine Andover Norton Factory Parts - Commando Parts

Andover Norton Parts are the only Norton spare parts in the market manufactured to original drawings, within the factory-approved tolerances, from the correct materials, and with the correct finish.

andover-norton.co.uk

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Yes, the clutch nut was loose -- movable, but trapped within the center tab washer (which had opened up a little).

JCP said:

Yes, the clutch nut was loose -- movable, but trapped within the center tab washer (which had opened up a little).

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The clutch tab washer is too soft and the nut works it way way loose
This leaves the clutch hub loose on the mainshaft etc

Pulled the shaft -- not a trace of either bushing. Minimal scoring on I.D. and shaft though.



And so I'm clear, two bushings (@1.2") are used?

https://steadfastcycles.com/product...ing-1-2-long-bush?_pos=1&_sid=a0eaadf63&_ss=r

JCP said:

Pulled the shaft -- not a trace of either bushing. Minimal scoring on I.D. and shaft though.

View attachment 81663

And so I'm clear, two bushings (@1.2") are used?

https://steadfastcycles.com/product...ing-1-2-long-bush?_pos=1&_sid=a0eaadf63&_ss=r

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As far as I can remember yes

baz said:

As far as I can remember yes

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Thanks

JCP said:

Thanks

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a suitably fat feeler gauge would have established no bushes from the start.

Wow, good job you found this before something even worse happened !

But, this should not happen… and you haven’t found out why it happened.

Best case scenario is that they were the wrong material or installed wrongly. If so, fitting new ones, properly, is all you gotta do.

But I suspect something else has gone wrong to cause this, perhaps a bent mainshaft? Perhaps poor choice of and / or inadequate oil? I dunno, but you really do need to look closely to find the root cause, otherwise it’s just gonna happen again.

When you look the bushes are cheap, but, you are into some serious effort to build the box back up with suspect parts and maybe then needing to do it again quite soon!

To fit the sleeve gear bushes you will need to remove the sleeve gear and use a press, if they just press in with the sleeve gear in situ in the gearbox it really will be a short-lived fix.

It looks from the images as if the bushes both need be pushed in from the outside end, so you will also need to make up a tool to press them in. (I haven't done the job, maybe someone who has can comment).

Check over any wear on the individual gears and bushes, including layshaft and the layshaft bush in the kickstart, and the selectors.

You have this box open, so surely you are changing the layshaft bearing for a suitable roller anyway!

Cost the sleeve gear complete with fitted bushes, a sleeve gear bearing, a layshaft bearing and a mainshaft, with bearing, maybe a layshaft! And a few other small bits, seals etc.

Putting that lot together is no more effort than reassembling the parts you have, and the rebuilt box should then last a very long time!

It's only money, right!

It IS only money. And not much of it really in the scheme of things.

Gearboxes are one of those things that should not be skimped.

There’s not much protection against a locked up gearbox, well actually there’s none apart from your choice of protective clothing and helmet, even a quick clutch hand won’t save you…

I used the RGM equivalent..... but other options are available

Yeah – lucky something much worse didn’t happen. And yes, I don’t know what happened; only that the final failure happened relatively quick (considering how long it must have taken for the full deterioration). The clutch went from fine to inoperable in 30 miles.

Next weekend I’ll methodically go through everything and report back. I’ve already ordered friction plates and a CNW hub, and I plan on replacing everything I touch that’s the slightest bit outta whack. I prefer to get everything squared away, and it is only money. And yes, not much in the scheme of things.

Does anyone have any thoughts on the interaction between this bushing and say, a too tight final drive chain (the chain stressing the front sprocket further as the swing arm arcs upward), or – to this same effect – shocks with more play (the result being a fuller swing of the swing arm). I’m just thinking out loud, trying to wrap my mind around potential scenarios for failure (outside of a failed component I may find) ... as in: in normal use, what stresses those bushes outside of the rotation of the related shaft. Like, something causing an eccentricity in the rotation of the sleeve gear, like the sprocket taking a directional force.

Not that what happened has to be related to some recent change, but the only change to the bike in the last 50 miles is that I swapped out incredibly stiff (useless) Emgo shocks the previous owner had on for a softer set of Hagons (that compress further -- arguably making the swing arm travel further – thus tensioning the chain more ... then the sprocket ... then the sleeve gear ... then the interior bush? )

Again, just thinking out loud.

I can’t quite work out if a too tight final drive chain would do that, I susoect that might manifest itself in other ways?

But a too tight primary chain could easily have caused it.

A too tight primary chain can cause the mainshaft to bow, clearly that bush hasn’t got space to allow for that, so the shaft will make space !

The original setup had 2 short bushes with a sizeable gap between them, that allowed them to wander and they wandered outwards and got chewed up by the clutch location circlip. The fix was to add a third short bush to fill the gap with loctite on the OD of all 3 bushes, 2 longer bushes would do the same fix also with loctite. A too tight primary will increase the load on the bushes, not sure if it contributes to the wandering bushes.