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Clutch drum end play

Submitted by peter_eldridge on Wed, 03/05/2023
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Commando

I've just been fitting an Alton starter to my 850 Mk1 - all went well but on re-assembly I noticed that I can move the clutch drum in and out about 1-2mm.

I can take up this play by tightening down the clutch push rod screw.

Is it normal to have some play? Or does it mean that the nut on the end of the shaft at the gearbox end is loose and/or the bushes are worn?

Any advice gratefully received before I strip it down. Thanks 

Submitted by steven_gould on Wed, 03/05/2023

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Hi Peter,

If the whole mainshaft is moving then I suspect the nut on the other end of the mainshaft has come loose. No need to strip down, just remove the outer gearbox cover and remove the clutch actuating arm nut, this might have come loose and if the nut is tight, the outer race of the bearing may be moving within the inner cover, the clutch actuating nut should hold this but if the bearing fit is no longer a press fit then you may need to loctite the bearing.

It goes without saying that if the bearing (in the inner cover) is badly worn, you may get axial play in the mainshaft. But I have not seen one that bad.

Finally, I assume that the clutch assembly retaining circlip, it's recessed washer (that stops the circlip jumping out) and shims have all been checked for integrity and still line up the outer clutch housing with the front engine sprocket.

Regards

Steve

Submitted by peter_eldridge on Thu, 04/05/2023

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Hi Steve

Thanks for the response. I've just taken the outer case off and the mainshaft nut was tight and the bearing looked OK - I assume I'll need to take off the inner case to replace the bearing?

Not sure what else to check?

At the other end of the shaft, I replaced the circlip and fitted the recessed washer and shims - so I think that end is fine

Regards. Pete

Submitted by stan_thomas on Thu, 04/05/2023

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While the clutch is off, can you move the mainshaft in and out? If so then you'll have to follow Stephen's directions and pull the gearbox cover(s) off. If the mainshaft is firmly located then, with the clutch plates out, mount up the clutch on the mainshaft and you'll quickly find where the play is coming from.

Submitted by philip_hannam1 on Thu, 04/05/2023

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Has the thick spring washer that sits under the mainshaft nut been omitted by mistake? That would let the clutch body move about.

Checkout the diagram.......the washer is labelled as 60.  On my gearbox the item is a shake-proof washer.

Attachments
Commando Clutch.jpg

Submitted by peter_eldridge on Sat, 06/05/2023

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Thanks for the responses.

I removed the clutch plates and checked end float at the clutch centre - it was almost nothing.

So I guess that means the mainshaft & nut is OK and the problem is just down to wear between the clutch centre and clutch drum.

I have already replaced the bearing, so I don't think there's much else I can do?

I've been thinking of getting a belt drive kit to go with the Alton starter anyway (I may look for some advice between RGM and Norvil!?), so that should take care of the clutch drum. If that doesn't cure the problem then I guess I could replace the clutch centre.

Thanks again for the help.

Submitted by philip_hannam1 on Sat, 06/05/2023

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The clutch body sits on the Gearbox mainshaft which in turn runs through the sprocket sleeve gear pinion.  Changing the large bearing for the Sprocket Sleeve Gear is not going affect movement of the mainshaft.  Any 'push-pull' movement of the mainshaft will be down to the small bearing that sits in the inner shell at the far end of the mainshaft. This could be worn out or have a loose nut on it.

 



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