Transmission slipping at high revs and have no idea why

[owain]

When I took everything apart, there were only 2 lobes on the sprocket and 2 lobes on the cush drive. There definitely weren't 4 lobes on either. Perhaps it may appear that way because I tried grinding the profile of the lobes with a dremel in a bid to stop them sliding over each other. :/

[BSA_54A10]

It looks very wrong to me an also looks like they are jumping over each other.

[Topdad]

I totally agree , there is something completely wrong with that cush drive unit and I feel you may be stuck in Llandudno for some time if you don't change 'em . Is there any one on the forum in England who may have so spare bits of a plunger cush drive for you ?  I can't see any other way to deal with it except change it !

[Greybeard]

Owain, you are about 80 miles from Andrew Guttman at Priory Magnetos who is very likely to have what you need.

[BSA_54A10]

When I took everything apart, there were only 2 lobes on the sprocket and 2 lobes on the cush drive. There definitely weren't 4 lobes on either. Perhaps it may appear that way because I tried grinding the profile of the lobes with a dremel in a bid to stop them sliding over each other. :/

Well now I have read you post properly, it confirms things.
The lobes should not be able to pass over each other with the cush nut done up to the shoulder.
You can check this without the spring.
If they can skip over each other then they either are not a set or are worn beyond their useable limits.

[owain]

Thanks for all the help on this issue. I ordered a new old stock sprocket/cush drive sleeve/ such drive cam/ etc. When comparing parts it was very obvious why cush drive and sprocket lobed were sliding past each other...The back of the sprocket and cush drive sleeve were incredibly badly worn...in fact it had even won abit of the crankhousing behind the sprocket as well. (New parts on left/ Old parts on right).

[ellis]

That's the ticket owain now you will soon be up and running with no slippage.   


ELLIS

[duTch]

 Given the step in the flange part, I don't think it's worn like that, otherwise you'd also have a step in the worn part- I would suspect the sprocket part has been machined to accommodate some clutch mis-alignment which you'll need to address as you re-assemble (though I can't imagine how that would happen to such a degree, but still worth addressing).. good luck with it, you're lucky to find the parts and I think the sleeve part may be from a '54 on as the flange seems a bit wider than the other (not stepped), to accommodate a seal- but should still fit