Touchy Feely

[Mosin]

Here are some pictures of the clutch centre as requested. As you can see, it slots perfectly well through the hole in the sliding plate when the primary inner case is off the bike. But there does seem to be some problem with its ability to slide home on the gearbox centre shaft.

Your ideas and suggestions are most welcome fellas, keep them coming!

[bsa-bill]

Looks to me like your centre is of the original type and probably OK, I base this on the internal thread for the puller as the repro ones I've seen have very little thread for this (one turn) and the scroll on yours looks like it is right ( kind of hard to get my old brain around what's clock or anti clock in a photo these days), if this is the case then the taper is probably ok.
This leaves the position of the engine,geabox,main-shaft or the primary case in question.
Don't think you want to delving into the gearbox without good reason Mosin so I would suggest removing the primary inner case and assemble the clutch and cushdrive then check chain alignment, then lets see what is good and not so good.
Is this possibly going to be something strange like bent engine plates ?

all the best - Bill

[chaterlea25]

HI Again Simon,
The point of my observations were that when assembled the scrolled part ofthe clutch centre
should be sitting well into the sliding plate, not fully hard up into it but almost,
I dont think its possible to assemble the engine / gearbox plates wrongly so the gearbox would be out of line
but at this stage I'm running out of ideas!!
By any chance do you still have the remains of the original clutch centre?
If you have sit that on the gearbox shaft and see where the back of the scrolled bit sits relative to the sprocket nut and compare with the new one!
By any chance was the inner primary case loose when you took the earlier photos which show the gap???
I'm presuming the spacer and gaskets are fitted between the crankcase and inner primary?
The total thickness of these should be around 0.130 in, in a previous reply its said the spacers should be 0.090 and say 0.040 for the  gaskets??
Fit a 5/16 bolt into the centre front hole to pull that side in as well as the two rear bolts before you check the position of the scrolled bit to the plate,

If you assemble the drive without the cases as Bill says lets see how much misalignment is there??

Its possible to turn out the tapered hole a bit to let the centre go onto the shaft a bit further,
It takes careful setting up and I have found using a spare shaft helpful for setting the taper on the lathe
Also as you know already a certain amount of shim/spacer can be fitted between the crank spacer and splined sleeve.

If you get the sprockets lined up, then its possible to reposition the inner primary case to a degree by adding or removing gaskets or fitting a thicker /thinner spacer between crankcase and primary

Awaiting the next episode ????
John O R

[Mosin]

I think we might be making some progress.

For the record, I removed the primary inner casing a couple of days ago, figuring that the most important task was to get the two sprockets to line up. Once I have done that I will sort out fitting the casings around them!

I am attaching a photo of the remains of the old six spring clutch centre alongside the new four spring centre. It can clearly be seen that the collar on the old centre is shallower than the scrolling on the new one by almost exactly the same distance as my sprockets are out of alignment (5mm). It stands to reason then that with the old centre, the clutch would be able to sit further back along the gearbox mainshaft, thus bringing the sprockets into alignment.

Yesterday I spoke to the chap I bought the clutch off and as it happens I am working in the vicinity of his workshop this afternoon, so I have arranged to take the clutch centre along and try it on an A7 which he has got there. This bike is also running a four spring clutch so we will be able to compare the two centres side by side and this should reveal a great deal I hope.

I will keep you informed.

Incidentally, the second photo is purely to show the damage I had to do to the old clutch centre just to get it off the shaft back in February. Even now I'm amazed that it came off without even marking the shaft at all!

[Mosin]

It's fixed!

And it turns out that the clutch was fine all along. This afternoon I went to see Paul from JB Restorations who I bought the clutch from. He is a top bloke and It turns out he knows quite a bit about BSAs! He informed me that unbeknown to a lot of people, BSA actually made two different types of cush drive sleeve, both the same length, but with different thickness flanges on them. He supplied me with one with a thicker flange and tonight I fitted it and guess what? With a few shims added for final adjustment, both sprockets finally line up perfectly and the primary case goes on as well!

I am amazed that no-one else has experienced a similar problem on here, but hopefully by documenting my experiences here I can save a huge amount of time and sleepless nights for the next poor sod who has a similar problem!

Anyway, a picture tells a thousand words, so here you go:

[chaterlea25]

Hi Simon
Every day's a school day

Cheers
John O R

[wilko]

I knew all along,  i just wanted you to suffer! 

[muskrat]

Great work. Now the ? is which one is for which model, and their part #'s. I knew the plunger/rigid differed from the S/Arm.
Cheers

[bsa-bill]

Nice one Simon - it's been a bit of a journey but you got the answer that benefits us all

All the best - Bill