I've just removed the primary chain case from my 1950 B33 plunger and noticed that there was play in the chainwheel causing it to not run true. Having stripped the clutch I still haven't got to the bottom of the problem, but according to Draganfly there should be a felt and a cork washer, parts 24-4232 and 66-3090 behind the sleeve (photo). Can anyone confirm whether these are normally fitted?
I'm presuming that the centre nut clamps everything tight so if everythings clean without burrs, it should work?
Hi greenfield,
Ive just rebuilt the 6 spring clutch on my 1949 B31.
I'm still not sure so we might both learn something here. I fitted the clutch with both felt and cork washers as on the diagram and after tightening up the clutch centre and fitting the plates etc. the chain wheel would not turn. I removed the cork washer leaving the felt washer and it was slightly better but still tight and not spinning freely. I decided to try with neither and just the sleeve into the brass/bronze bush on the plate. The clutch felt much better and also had better alignment with the drive sprocket for the primary chain. Here's the thing though, I haven't yet had it out on a run to see how it works or how it might leak! Sat in the workshop I can select all gears and neutral when running on the main stand.
The draganfly exploded diagram does say (plunger only) next to the felt and cork washers. Mine is a rigid frame but aim not sure why this would make a difference. I hope someone can enlighten us?
Pete
Hi Pete
Just done some measuring. The length of the exposed shaft is 55mm and the length of the sleeve is 37mm. This gives 18mm free. When the sleeve is fitted there is 17mm exposed. Therefore roughly there's 1mm gap behind the sleeve. There's no way of fitting any felt or anything behind it.
There is quite a gap when the sleeve enters the sliding plate. There's a spiral groove on the sleeve collar. This should return oil to the primary drive but how effective is it? I can't see any other means of stopping oil escaping.
Back to my original issue. I have now discovered that a poorly fitted woodruff key prevented the sleeve seating fully on the shaft. I think that this is the source of the wobble. When I dismantled the clutch, the centre nut had been glued on to the shaft with the lockwasher not turned over, and the sleeve came off without a puller.
Cheers
Hi greenfield,
Yes thanks for the update.
As I say I'm not sure but i wonder when you actually fit the clutch centre nut and tighten (high torque) it might actually seat further in taking up that 1mm you mention??
I must say I have not folded over the tab washer either as i was unable to get a suitable tool into the space available. I just put some medium strength loctite on the thread.
Just checking, but you do have the large felt washer behind the sliding plate fitted don't you?
I'll update further if I discover anything else.
Pete
Yes, there's a felt washer. Before I reassemble I think I'll replace the sliding plate and fit a new felt washer as the hole in the plate is oval. When I got the bike it was covered in oil and I suspect that its been coming out of multiple places. At least its preserved a lot of the metalwork.
Hi greenfield,
Ive done a bit of reading around and discovered that the later gearboxes had a slightly longer main shaft , might this be what allows the cork and felt washers to be fitted?
I would assume though that you'd have a later gearbox as the earlier boxes were fitted up to 1948 according to what Ive read.
Also picking up on your point that it was leaking oil from multiple places - it might be that your crankcase breather is blocked/ not working. This can cause the internal crankcase to become pressurised when running and force oil through any available gap.
Pete
the 46-48 gearbox with the shorter mainshaft does not fit into the frame of the later models.
see this link http://pub37.bravenet.com/forum/static/show.php?usernum=3155626639&frmid=16&msgid=1438450&cmd=show
If the sliding plate is a source of oil leaks it is possible to buy expensive versions with an oil seal incorporated...or if you have access to a lathe you can make one up for a couple of quid.
On the subject of the cork washer...is this a 6 spring or single spring clutch? I don't remember a cork on the 6 spring although the single spring does have one (that nobody bothers to fit usually)
this one that you can buy for a Goldstar
(https://i.ibb.co/7rLPDvz/bsa-goldstar-oil-seal-sliding-plate.jpg) (https://ibb.co/9yS60nv)
and here's one I made for my B31
(https://i.ibb.co/NntnkQt/primary-sliding-plate-with-seal-s.jpg) (https://ibb.co/qF7F4X7)
(https://i.ibb.co/Mc1SJG4/sliding-plate-with-oil-seal-s.jpg) (https://ibb.co/k4DBP9f)
Thanks Petes
Its a 6 spring clutch and its starting to make sense now.
A poorly fitted woodruff key prevented the sleeve seating properly, which produced a wobble in the chainwheel which in turn enlarged the hole in the sliding plate and wore the primary chain. Don't you just love restoring previous incompetency!
Just about everything on the bike needs looking at. I've just started investigating the electrics and a significant amount of the wiring looks to be household twinflex. It'll certainly keep me busy over the next few months.
Oh dear... Should I feel guilty?
Very impressed with Pete C's sliding plate mod. This topic has been a revelation to me. On rebuilding my B31 Bitza (1954 plunger frame, 1950 engine, God-knows what year gearbox) purchased as a non-runner, I was confronted with a 0.210" misalignment of the primary chain sprockets. This was with both the original 6-spring clutch and a replacement Triumph-type 4-spring job. I spent weeks trying to get to the bottom of this (in my pre-forum days......yes I know!). All the pictures I could find of gearboxes seemed to have identical mainshafts. In the end I resorted to moving the engine sprocket and complete primary chaincase outboard by 0.210" which required a bit of modification to the engine sprocket cushdrive in order for it to function properly. It all seems to work quite satisfactorily but if only I had known there are different mainshafts. Curiously though, with this set-up there is just the right gap between the clutch sleeve and the gearbox pinion sleeve/sprocket to nicely compress the cork washer and felt washers. However, on running the bike there was an oil leak from this area. I finally established that it was gearbox oil coming from between the pinion sleeve (which carries the sprocket) and the mainshaft. My fix with an 'O'ring seems to have sorted this – see my previous post (there aren't many).
If you have to investigate the electrics I would say it is probably easier to just rip everything out and completely rewire. These are so simple even I, with a horror of anything electrical, managed it. In fact I've done it now on each of my BSA bikes (M21, B31, B33).
A new loom costs about 25 quid which is cheap for an afternoon's entertainment fitting it and the peace of mind knowing that it is probably going to outlast you.
The loom on my B33 wasn't too bad when I got it but ALL the wires were black, and the thought of having to find a fault on the roadside one day was keeping me awake at nights.