Morning gents,

I'm restoring an M21 which I obtained as boxes of bits, and have received a lot of help from the fellas at the BritBike website. However, I have a question which I am advised to rather ask you gentlemen.

My bike has the single spring clutch, and my question is: outside of the clutch nut is there supposed to be a locknut fitted? No parts list or diagram I have ever seen features such a thing, however one of the gents on BritBike thinks there should be, and I also have a nut which seems to have no home to go to, but turns out to fit perfectly on the inner thread of the clutch shaft and bears on the clutch nut - thereby working perfectly as a locknut. On the other hand, it has a hex head and the chap I was talking to remembers it being a C-spanner type nut.

Can anyone advise me?

Thanks,

Ian

email (option): iwiggins@cbi-electric.com

There is just the sleeve nut #62 which holds the clutch to the mainshaft (I use Loctite) and the big nut #85 which compresses the spring. The only hex nut I can think of is #82 which holds the ball bearing retainer in the clutch cover plate. Ron


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email (option): ronpier@talk21.com

Yes, thanks Ron, that's how I understood it. And I wouldn't have given it another thought except for someone telling me that there should be a locknut.

However, have a look at this picture (which I finally figured out how to download).

Could this have been a factory option or a common modification or something like that?

(Please ignore the broken studs by the way)



Cheers,

Ian

email (option): iwiggins@cbi-electric.com

Well I've never seen that! Does the clutch cover plate actually fit without fowling? I think that when the actual spring nut is done up tight, it's held from undoing by the biggest 'spring washer' in creation. However, the cush drive nut is prone to undo itself under inertia (Again I use Loctite) Has anyone ever had the single spring clutch nut come undone? Ron

email (option): ronpier@talk21.com

Sleeve nut yes
Spring nut no
Like every one else some blue or green loctite on the sleeve nut and do up with a rattle gun

Uf theat nut is very long it might have been used as a spring compressor to get that !%#? clutch spring started.

email (option): bsansw1@tpg.com.au

Trevor has a point! BSA's way of getting the spring nut started is to press something up against it, which is something I've never wanted to try! I have my home made tool and rattle gun with special socket. Maybe that hex nut is a compressing tool? Ron

email (option): ronpier@talk21.com

Hmmm...

Don't think it's a spring compressor. If you look below, the thread is much too short. Unless perhaps used in conjunction with a 5/16" rod, but then why would it need to be threaded?

Actually it's just curiosity driving this now. I think we can accept that a locknut is neither standard nor needed - it's just that I had one gentleman telling me that there should be a lock nut (or perhaps his bike had one), and I had an odd nut that seemed to fit nowhere, but was just the right size and shape to fill the role of the theoretical lock nut! I added two and two and got five perhaps, but I'm still curious!