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Comet clutch centre splines

derek

Well Known and Active Website User
VOC Member
I think that the problem with the clutch centre, is that the spline length is only 1/4" and only about 3/16" engage on the shaft. improvement can be made by replacing the thick washer (one thick one thin either side of the rollers, chainwheel bearing) the inside one, for the thiner one. ie. two thin washers: I improved mine further, by using the thick washer but counter boring it and machining the back of the clutch centre to suit, I now have a full 1/4" engagement of the splines. With regaurds to locking the nut, it can be tapped and a grub screw used to tighten against the clutch centre. The now supplied nuts are larger (mine 32mm across flats) allowing this to be done. Although, I have only used thread lock.
 

Vic Youel

Well Known and Active Website User
Non-VOC Member
Burman splines

It is a pretty awful design though and the Conway Honda conversion, which I have adopted after my splines stripped, makes far better use of the spline depth.....half and inch or so but I wonder how long the skinny bearing will last?

Anther solution would be to modify the shaft and centre with deeper and wider splines for the quarter inch depth.

Cheers

Vic
 

A_HRD

Well Known and Active Website User
VOC Member
Clutch Bearing/Centre Modification

I think that the problem with the clutch centre, is that the spline length is only 1/4" and only about 3/16" engage on the shaft. improvement can be made by replacing the thick washer (one thick one thin either side of the rollers, chainwheel bearing) the inside one, for the thiner one. ie. two thin washers: .

Derek,

I accept I may have mis-understood you here, but it seems to me that doing this will lead to chain misalignment twixt clutch sprocket and engine sprocket.

Incidentally, I removed the clutch from my Tatty Commuting/Shopping Comet last week to clean it all up in the hope of improving the crunch when selecting first at stand-still. I strongly believe that its never been off ever before (the engine has never been apart either). I struggled for 2 hours to get the clutch nut undone - even with a thick steel clutch plate welded to a strong handle to hold the plot still - and a 3 foot wrecker bar. In the end, I borrowed an air wrench and after about 15 seconds of continuous running this tool did the trick at 90psi.

What surprised me was that the splines on the shaft and clutch centre were like new and I know for a fact they've done a little over 50K miles from new on short trips in commuter traffic. The mainshaft splines measured 0.127 ins with my digital vernier. The conclusion I draw from that is that a thoroughly tight mainshaft nut does much to keep the splines in good shape over long periods of time - despite the poor amount of engagement. A loose nut can do untold damage in just a few miles.

Peter B
Bristol, UK.
 

donrapide

Website User
Non-VOC Member
Can only agree with A HRD about the need for a tight clutch nut.

Do not use the thin mild steel locking tab washer, it squashes out under the stress of the tight nut, find another way to lock the nut. Also fit a large, thick washer under the nut. If possible find a washer that is dished and fit it with the concave face to the clutch.

If the splines are slack see if you can fit steel shim material in the gap, turning the hub in the drive rotation before fitting same. I've use slivers of cat food tins before.

The end of the shaft splines should be below the surface of the drum, it would be very unusual if they were not but check anyway.
 

derek

Well Known and Active Website User
VOC Member
fitting thinner washer.

Fitting a thinner washer or as I described, does not alter chain alignment, as this is dictated by the inboard already thin washer, it is the outboard washer and clutch center that I altered. Derek
 

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