A7SS Gearbox

[MikeN]

Your clutch is  now dragging because ,as you say ,you have loosened the adjuster off too much and so now you dont have enough pull on the lever.
 So next,remove chaincase and check and adjust the pressure plate spring adjusters  (you could have 5,4 or 3 springs depending on which clutch you have ).If they are all right, then undo them and pull out all the clutch-plates and check the friction plates for wear (lack of friction material).
 Also check plates are not "hanging up" (unlikely)and are actually being compressed by the pressure plate
 When Ive worked on clutches I often go for a short ride to try it out before re-fitting the chain case.You can rest your left foot on the pillion f/rest to keep it clear of the chain.
Mike

[BSA_54A10]

1) go to ATF in the primary
2) clutch plates oily ?
3) clutch springs too weak or binding.
4) cage or center with deep notches
5) hub not seated properly and spinning on mainshaft

[Mosin]

I'll give it a go..... What could possible go wrong.....?

[Mosin]

Well, I have now had my clutch to bits as suggested. Because I have never worked on one before, I don't really have anything to compare it too in terms of wear on the friction plates. However, none of the plates were oily and the springs were all the same length. I tightened the springs each one in turn to ensure a uniform pressure and I now have the clutch so tight that I can only just pull it in at the lever but it is still slipping when under load. Incidentally, it has six springs. At low speed/revs it seems to be working ok and it is engaging fine (even though it is very stiff) it just seems to be slipping under load. I am inclined to think that it is probably not simply a case of wear on the friction plates as it was working fine before I started messing with the gearbox.

I am now getting very frustrated with it having spent the past three hours riding it up and down the road with my left fut on the pillion peg and the chaincase off stopping every couple of hundred yards to adjust all the nuts or the push rod. None of which have left me feeling as though I am getting any closer to actually making the thing work again.

Any suggestions would be most welcome.

Simon   

[trevinoz]

This may be a silly question, have you checked that the shaft key is still intact?
I have seen this problem on an A65 with the key sheared off.
Trev.

[Mosin]

Trev,

I have had a look at the exploded diagram in my Haynes manual and I can't see any mentio of a shaft key. Perhaps the A65 is slightly different?

Simon

[BSA_54A10]

The clutch set up is the same for every BSA ever made with the exception of the Bantam and the bolt on gearboxes both of which have a splined mainshaft.
There is a key.
Its purpose is to index the hub to the main shaft and to prevent the hub turning on the mainshaft when you tighten the clutch nut.

[Mosin]

I've found the key! It was on the gearbox diagram in Haynes rather than on the clutch diagram! I have also found it on the bike and it appears to be completely intact.

However... I did notice that some of the "fins" on the Clutch chainwheel which form the housing for the clutch plates appear to be bent outwards slightly i.e. they are not at ninety degrees to the chainwheel itself. I suspect that this may possibly be my problem because they appear to be allowing the plates to rotate within them rather than gripping. Does this sound like it might be possible? Also, is it permissable just to have a go at bending these "fins" back up to ninety degrees to the chainwheel or am I looking at having to buy a new chainwheel? Finally, Haynes is showing some sort of shroud which appears to go around the outside of these fins (presumably to prevent ATF from making it onto the plates) My bike does not appear to have any sort of shroud like this. Is this likely to be a problem?

Simon


 

[RichardL]

Mosin,

You could straighten out those fingers yourself and, if careful to get them all at 90 deg. to the chain wheel, you should be good. Examine the slots between the fingers where the plates fit. These must be free of nicks and gouges, any found should be filed out, leaving a nice clean edge along the slot. Otherwise, buy a new pattern basket for around 35 GBP. The one I bought was not great, but OK, the problem was that one or two studs spun where they were pressed into the basket. the fix was to braze them all in place. Maybe a first-rate N.O.S. basket would not have that problem, but I didn't know where to get one.

Richard L

[trevinoz]

Simon,
           you must have an early basket. Later ones have a band around the outside to prevent what has happened to yours.
You could straighten it and modify it with a strip of sheet metal tacked to the outer diameter.
Trev.

[RichardL]

Trev,
Perhaps I read too fast. I thought Mosin was talking about the inner basket. Nevetheless, I think what I suggested still applies, except, of course, regarding the studs. Very interesting about the early baskets not having the band.

Mosin,
Are talking about the tines for fitting the inner tabs of the plain steel plates or the outer tabs of the friction plates.

Richard L.

[Mosin]

Sorry, I am talking about the outer basket. The one with the slots for fitting the outer tabs of the friction plates. The tines which form these slots were splayed outwards by a few degrees - probably due to the absence of this strip of metal which Trev mentions. This appears to mean that only the innermost friction plates are actually engaging with these slots and the outer ones are rotating freely within the basket. I have carefully bent the tines back up to ninety degrees and reassembled the whole thing. I will give it a go when I get back from work today, but I am cautiously optimistic.....

Mind you, I've said that before....

Simon

[Mosin]

Well, I've had the bike out for a spin and the good news is that the clutch started off working perfectly! The bad news is that after about two miles the fins/fingers/tines/whateveryouwanttocallem had splayed back out and the pressure plates were spinning freely in the basket again with all the clutch-slipping consequenses.

So, now I know what the problem is and it looks like I'll be ringing round tomorrow to see who can sell me a new clutch chain wheel. Preferably one with a metal band on it to prevent this happening again.

[Mosin]

Just by way of a follow up, I got hold of a NOS clutch basket off ebay (one with a band around it) and I fitted it yesterday. It works absolutely fine. So now I finally have four working gears and a working clutch! All I need is for it to stop raining for five minutes and it's off the the MOT Test Centre for me!

Thanks for all the help guys. I would have been completely lost without it.

Simon

[chaterlea25]

Hi Simon,
Glad to hear all is well again,
Did you check the tangs on the plates that engage with the chainwheel for damage?
If they were skipping on the old one they might have been rounded off! they should have sharp corners and the plates should be a reasonably close fit in the basket
Regards
John O R