classic motorcycle forum

sorry I,m not that technicly minded.but I,ll try ,it looks like 18 and measures 5/16ths across. regards steve

thanks,that helps very much,i have had it on and off the shaft a few times, there is a big wobble and I agree it seems to be be the centre rocking on the bearings, but when you say it will be less when its all put back together the wobble is still quite big even with the clutch plates and springs are fitted.that is when my problem started cos I have broken one of the clutch spring nuts and a couple of the others are a bit iffy. so I ordered new clutch spring nuts on line.these are the ones that don,t fit,but I am assured by the seller that these are standard threads.so if I need a new backplate I need to get it apart and that's the bit I,m stuck on.while its on the bench I need to sort it out properly before the engine goes back into the bike.how do you get the plate off the front when the four countersunk screws have been removed.( when I have got it off I will probably take it  to a proper b.s.a. supplier to get the correct parts),cheers guys.it is a retirement project so although its sometimes frustrating it is also still  a great deal of fun !

hi john, right, I,ve stared at it some more and read the manuals. I,ve removed the four countersunk screws and then it says prize off the retaining plate. that's the bit I,m stuck on . how the heck do I get the plate off? bearing in mind I don,t want to damage the studs.. I know its probably been on for 50+years but it feels like its welded on !

cheers mate, I have already pulled the clutch off and ,removed the plates,but my clutch doesn,t look anything like the books. the backplate with the studs maybe has been replaced at some time as this is what the clutch spring nuts screw onto. i still hav,nt found how to get into it and the books don,t help much !

hi guys, this engine overhaul is still giving me loads of problems.i have began work on the clutch and having got the new cluth spring nuts I,ve found that they are fractionately smaller than than the studs on mine.it is clear that the clutch has been changed at some time as this is nothing like the c15 clutch seen in all the manuals etc. my chainwheel  has 40-3204 stamped on the back of it,and although it is still a 4 plate and  fits on the shaft/keyway o.k however there is a wobble/play so probably needs needs new rollers but I hav,nt a clue how to strip it  down any further.  I thought about re tapping the studs to fit my spring nuts but can,t get at them.i know its a long shot but if anyone recognises the number stamped on the back of it or knows what this clutch maybe off,then maybe I can progress further.any help would be appreciated,kind regards, steve.

hi guys, didn't get any replies to my last post,so I thought I,d try and clarify my question and see if anyone can help. when I stripped the primary drive side down,the large nut holding the chainwheel and clutch hub only had a thick washer behind it.i have now bought a tab washer,like it shows in the manuals,it has two wide tabs on it  which I presume lock the nut after tightening and one longer thin tab, but the hub doesn't seem to have any grooves anywhere for the tab to fit. the only groove I can see is where the woodruff key fits on the shaft.i really can,t fathom out how to fit this tab washer so it locks the nut.any help would be appreciated, thanks.

thanks for the help ,i,ve left the chain off and running the engine,the clutch works ok.and I can go down from neutral to first and back up through neutral to second, but then the gear change doesn,t come up any further.