The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: Daniel Toro (DT) on 27.03. 2009 15:08

Title: Some help with the CLUTCH
Post by: Daniel Toro (DT) on 27.03. 2009 15:08
Hi all.

I need change my clutch (or put one) and I have a few doubts.

First, my clutch doesn't have the cover.
And looking the manual, i don't know how to fix if I buy one.
I need buy the sprockets too?

The picture is attached.

Well, looking at the ebay i found this itens:

http://cgi.ebay.co.uk/6-NEW-CLUTCH-SPRINGS-BSA-A-B-PLUNGER-MODELS-A7-A10_W0QQitemZ360111564483QQihZ023QQcategoryZ108839QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262?_trksid=p1742.m153.l1262 (http://cgi.ebay.co.uk/6-NEW-CLUTCH-SPRINGS-BSA-A-B-PLUNGER-MODELS-A7-A10_W0QQitemZ360111564483QQihZ023QQcategoryZ108839QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262?_trksid=p1742.m153.l1262)

http://cgi.ebay.co.uk/5-NEW-SURFLEX-CLUTCH-PLATES-BSA-A7-A10-PLUNGER-6SPRING_W0QQitemZ140302917280QQihZ004QQcategoryZ108839QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262?_trksid=p1742.m153.l1262 (http://cgi.ebay.co.uk/5-NEW-SURFLEX-CLUTCH-PLATES-BSA-A7-A10-PLUNGER-6SPRING_W0QQitemZ140302917280QQihZ004QQcategoryZ108839QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262?_trksid=p1742.m153.l1262)

http://cgi.ebay.co.uk/5-SURFLEX-STEEL-CLUTCH-PLATES-BSA-C10-C11G-C12-A7-A10_W0QQitemZ360028758583QQihZ023QQcategoryZ108839QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262?_trksid=p1742.m153.l1262 (http://cgi.ebay.co.uk/5-SURFLEX-STEEL-CLUTCH-PLATES-BSA-C10-C11G-C12-A7-A10_W0QQitemZ360028758583QQihZ023QQcategoryZ108839QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262?_trksid=p1742.m153.l1262)


Is that correct?
I have ony 3 friction plates and steel plates.
Have 1 tick and 4 thin, right?

oh, i don't have the petrol taps too, i put one of some honda motorcycle.
Suggestions?


Many thanks.




Title: Re: Some help with the CLUTCH
Post by: beezalex on 27.03. 2009 17:46
Senor Loco,

Those springs look a little spindly to me....don't really know if they're right, kinda hard to tell.  I'd buy from Draganfly or Domiracer to be sure.

BTW, you should have five friction plates, five thin steel plates and one thick steel plate at the back.  I assume the set on ebay does not include the thick back plate.  Hope that helps.
Title: Re: Some help with the CLUTCH
Post by: a10gf on 27.03. 2009 21:01
DT, in addition to evaluating the ebay stuff, maybe download tha catalogues from f.ex http://www.draganfly.co.uk/ and http://www.srm-engineering.com/ and send them some email questions. Lots of good reading, and I'm sure you'll end up ordering much more than clutch parts! If you prefer to deal with USA, maybe someone here can recommend dealers.

Sorry for hijacking the thread, but I have to ask, what's the special dynamo and ignition arrangement ?

e

Title: Re: Some help with the CLUTCH
Post by: BSA_54A10 on 27.03. 2009 22:51
As stated earlier your clutch is too small for an A10 and could very well be from an M or C series which have fewer plates ( because they have a lot less power) .
While the plates are all the same, the baskets & centers are different lengths to accomodate the different number of plates.
The thick plate goes at the front in the belief that it should go there to spread the pressure from the pressure plate evenly.

If you need to replace the sprockets as well you would be better off replacing the entire 6 spring job with the latter and much better 3 or 4 spring clutches.
 
Title: Re: Some help with the CLUTCH
Post by: trevinoz on 27.03. 2009 23:09
Trevor, it is a plunger bike. A bit hard to put any other clutch in.
Trev.
Title: Re: Some help with the CLUTCH
Post by: BSA_54A10 on 28.03. 2009 10:17
Should have looked at the photo a bit harder before posting,
Either the glasses or the brain obviously need attention.
Title: Re: Some help with the CLUTCH
Post by: Daniel Toro (DT) on 28.03. 2009 15:18
Thanks, i'll search on the suggested links.

But the doubt whit the cover continues, if i buy one, how can i fix?
Doesn't need to have something to attach the bolts?

A10gf, I awnser your question on a new post.

Title: Re: Some help with the CLUTCH
Post by: a10gf on 28.03. 2009 16:14
Here's the complete clutch, also try a search for clutch from the main forum page, you'll find lot's of posts.
& take a look here http://www.a7a10.net/forum/index.php?topic=348.0

e

http://www.a7a10.net/forum/index.php?action=dlattach;topic=919.0;attach=2192;image
Title: Re: Some help with the CLUTCH
Post by: a10gf on 28.03. 2009 16:40
yup, here's one showing all plates, and another showing detailed parts. (from service sheet 208 & 211).
And let me add that a well adjusted 6 spring works perfect.
Title: Re: Some help with the CLUTCH
Post by: RichardL on 28.03. 2009 17:00
It makes me wonder what a three or four-spring clutch feels like, not having eperienced one, since my six-spring also appears to work jsut fine (I have no way of knowing if it's "perfect.").

Richard L.
Title: Re: Some help with the CLUTCH
Post by: a10gf on 28.03. 2009 17:06
That's easy to spot, no slip or drag, + smooth clutch handle and smooth gear shift.
Title: Re: Some help with the CLUTCH
Post by: LJ. on 28.03. 2009 20:01
... and this is the difference between the early six spring clutch, which is so smooth and a joy to use, and the later six spring clutch which can be a downright devil to set up and operate! A later four spring clutch is also a joy to use and is very similar in operation to the early six spring. Yes there is a three spring clutch out there and also the big single spring one found on War Department M20s.
Title: Re: Some help with the CLUTCH
Post by: a10gf on 28.03. 2009 20:12
lj, thanks for the info, didn't know there were several 6 spring incarnations, must be the later one that is the source for the criticism that we read about now and then.
Title: Re: Some help with the CLUTCH
Post by: LJ. on 28.03. 2009 22:23
The two types of six spring clutches was only brought to my realisation a short while ago, thanks to Brian who mentions it in another thread a couple of weeks ago. In the past I was struggling to understand why so many liked the six spring and yet so many hated it! Of course, now I realise there were two! early and late, both different in construction and I belive it is the inner part that is responsible. Looking closely at the early one it is a better and much more solid construction than the later cheaper one. Who knows, there may even have been other variations between these two.
Title: Re: Some help with the CLUTCH
Post by: beezalex on 30.03. 2009 17:33
I wouldn't use "early" and "late" to distinguish the two six spring clutches since this is only true as it applies to A10's.  The wet six spring clutch with the crappy stamped center hub (the main reason why it's stink-o) was actually used BEFORE the dry clutch in the plunger A-series appeared in other bikes.  Perhaps "Dry 6-spring" and "wet 6-spring" would create less confusion.

Now, DT, if your clutch does not have the tin flange as shown in the drawing, you cannot attach the cover, though it is hard to imagine how someone could have fitted the wet-type six-spring clutch to a plunger gearbox mainshaft.  On top of that, there's no other BSA that used duplex chainwheel that would fit.  From that, I can only draw the conclusion that it is a plunger clutch and someone deliberately removed the flange.
Title: Re: Some help with the CLUTCH
Post by: Daniel Toro (DT) on 30.03. 2009 21:30
Thanks beezalex, i was thinking somewthing like that, can't attach the cover because come part is missing.
I'm looking for a place do buy all pieces, talking to 3 or 4 stores here recommendet.

I don't know why some things happens, or better, why some people take off some pieces.
But we try to bring the original back! hehe.

Title: Re: Some help with the CLUTCH
Post by: Richard on 30.03. 2009 22:32
DT
If the cover you are refering to is the one held on by all the small screws inside the primary chaincase I was told that it was originally there to keep the clutch plates dry, and it is now not required as the modern friction plates work even if they get oil on them i.e. they are wet plates.
Certainly on my 54 A10 plunger I have run a six spring clutch with replacement friction plates and no cover with no problems for a 12 month now.
Having said that I would love to find a direct replacement for that clutch as I have a george prew 4 spring on my 61 Super Rocket and you can pull the lever in with one finger not the super human effort it takes with the 6 spring!!
Richard
Title: Re: Some help with the CLUTCH
Post by: Daniel Toro (DT) on 31.03. 2009 00:48
Richard, that's it.
I was concerned about the oil and tha's the reason to look for a cover.
But you told everything, whit the new 'technologies' problaly this is'nt necessary anymore.

Thank you.
Title: Re: Some help with the CLUTCH
Post by: BSA_54A10 on 31.03. 2009 11:16
Quote
Having said that I would love to find a direct replacement for that clutch as I have a george prew 4 spring on my 61 Super Rocket and you can pull the lever in with one finger not the super human effort it takes with the 6 spring!!

But you can get a 6 spring alloy pressure plate and radial bearing lifter.
Pop one of these on then back off the clutch nuts till it starts to slip then tighten 1/2 turn
Result is a 2 finger clutch.


Quote
I was concerned about the oil and tha's the reason to look for a cover.
But you told everything, whit the new 'technologies' problaly this is'nt necessary anymore

OTOH you might like to try ATF in the primary.
It is very popular with the Notrun riders who consider that their 860 Commandos "too powerful for the conventional clutchs "
The good side is that ATF is pink & engine oil is black so it makes it easy to work out where those dribbles on the bottom of the primary are coming from.

 

Title: Re: Some help with the CLUTCH
Post by: beezalex on 31.03. 2009 15:51
You may be able to get the clutch to work wet, but it will never work as well as it does dry.  Simple fact is that the friction coefficient in oil is much lower than dry no matter what kind of friction material you use.  Pretty much all of the british wet clutches (Except the commando) are marginal as they came and the only reason the plunger A10 clutch works well is because it is dry.

Also, IMHO, there is no reason to run anything BUT ATF in a vintage british primary that doesn't share engine oil.  ATF is designed for wet clutches.