BSA C10 C11 C12

BSA C10 C11 C12 Forum => Technical Section => Topic started by: Steve P on October 09, 2019, 11:00:25 am

Title: C11G clutch
Post by: Steve P on October 09, 2019, 11:00:25 am
Hi
I'm new to the site so please accept my apologies if this subject has been covered. Could someone please point me in the right direction if so.

I purchased a 1955 semi assembled C11G a few weeks ago.

There's no clutch inside the chaincase! All that's in there is a splined shaft with a pushrod and two nuts, one of them a left hand thread.
I've been searching the internet for parts and things like the chainring/basket seem to be unobtainable.

Should I sink into the depths to despair? Or is there anything any member could suggest as a solution.

I believe the clutch is the three spring type. Does anyone know where I could purchase a complete clutch or at least the major components?
Has anyone managed to fit a different type of clutch onto the  gearbox shaft? If so any information would be gratefully received.

Cheers.

Steve
Title: Re: C11G clutch
Post by: Owen on October 09, 2019, 12:13:09 pm
Hi Steve P,
Welcome to the site please add your bike details to the register. You need a 3 spring clutch assembly for your bike. The bits come up on E Bay occasionally and members might have bits to help you out. Do you have a user and parts book for your bike? If not send me a personal message with your email address and I will send you some by email.
Title: Re: C11G clutch
Post by: johnboyfully on October 09, 2019, 12:22:52 pm
Welcome to the site Steve. Never despair! I’ve had my C12 for 3 years and (some day foolishly) I started a full strip down last January! She is almost back together. I’ve acquired a fair few spare parts and definitely have some clutch parts. Can you let me know exactly what you need by either description or part number and I will do what I can to help you out. I’m no mechanic or engineer believe me and it can be very frustrating at times but I’ve learnt that it is all part of the never ending learning process. But I love my little bike and I’m really looking forward to see, hear and smell her breathe again! There is a wealth of knowledge and experience on here and they are all very patient with novices like me!! True they sometimes argue like married couples over seemingly minor issues but that’s just part of the banter. Good luck with your project. Cheers, JBF
Title: Re: C11G clutch
Post by: Steve P on October 09, 2019, 02:30:41 pm
Hi thanks for replies.

Owen, I do have the parts lists and service book - both from Draganfly. I'm struggling to find where to register my bike details. Should I include non BSA models.

JBF, thanks for the sympathy. I'm looking forward to actually riding the bike, I think this may be some time coming. My knees and back no longer cope with kickstarting 750 and 850 twins. I think there's going to be a bit of a learning curve.

I'm looking for all the major clutch parts. I'll probably buy new bearings, rubbers, plates and bolts. I'm hoping these more consumable parts should be fairly readily available.
I think what I'm looking for is;
Chain wheel - 29-3461
Centre end plate - 29-3466
Centre vane - 29-3465
Centre - 29-3464
Spring plate - 29-3467
Thrust washer - 29-3473

Any help is really appreciated

Steve
Title: Re: C11G clutch
Post by: johnboyfully on October 09, 2019, 03:42:55 pm
I’ll have a look and get back to you in a day or so Steve. I’ve definitely got a thrust washer as I bought one recently (inadvertently)! Cheers, JBF
Title: Re: C11G clutch
Post by: Steve P on October 09, 2019, 04:49:56 pm
Thanks JBF
I really appreciate your help
Steve
Title: Re: C11G clutch
Post by: Owen on October 09, 2019, 05:03:56 pm
Try the following link
http://bsac10c11c12.co.uk/smf/index.php?action=form;n=5

Only bsa C models please.
Title: Re: C11G clutch
Post by: Steve P on October 09, 2019, 05:24:36 pm
Thanks Owen I've registered.
Title: Re: C11G clutch
Post by: chaterlea25 on October 09, 2019, 07:32:57 pm
Hi Steve,
According to this topic the clutch is the same as AJS14 / Matchless G2 which would widen the search

https://bsac10c11c12.co.uk/smf/technical/some-useful-parts-info/msg51696/#msg51696

John
Title: Re: C11G clutch
Post by: Steve P on October 09, 2019, 07:51:38 pm
Thanks John
Great info and help
Title: Re: C11G clutch
Post by: BSAc11g on October 10, 2019, 04:08:57 am
AFAIK ( or think I know ) the early gearboxes where made by BSA thus have a taper & key for the clutch hub to mount on and as such almost any BSA clutch can be made to fit.
The latter light box , like the A series plunger box was bought in and is a Burman box thus the splined main shaft and the fact that non BSA clutches drop strait in.
Also the earlier tapered end main shaft can be retro fitted in finding a clutch hub is a big problem.
It all depends upon how confident you are and how much buggering around you fell like doing.

You will need an early & late parts book to see which parts interchange.
I have helped a member to fit the A series splined main shaft into an M 21  box so he could fit the 4 spring clutch and duplex chains.
Apart from the massive increase in primary ratio requiring the fitting of a side car drive sprocket it worked really well.
Title: Re: C11G clutch
Post by: Steve P on October 10, 2019, 09:33:17 am
Hi Trevor
Thanks for the info., and help.
I'm trying to leave the gearbox in one piece if possible. This is obviously a solution if all else fails. Thanks.

This is really helpful information.

In the past I've built a Norton with an AMC box and an AJS with a Burman box.
I just didn't have a forum like this to help.

Thanks everyone

Steve
Title: Re: C11G clutch
Post by: BSAc11g on October 10, 2019, 02:43:25 pm
It is nothing odd to open a BSA box and find 4 pairs of gears from 4 different boxes in there.
One of the reasons why Gold Stars had such success is you can build up near 30 different ratio boxes.
Thus it was affordable for weekend clubman racers to have a different box for every track.
From memory BSA made 8 different boxes for them.
One of the C series clusters is the same as an A series cluster but only 2/3 the price so it was very common to buy C boxes, strip the cluster out then scrap the cases which is most likely why come boxes are really hard to come by now days.
Title: Re: C11G clutch
Post by: Steve P on October 10, 2019, 05:03:54 pm
There must be stocks of these cases somewhere. I suppose they'll be with all those Norton engines and triumph frames left over from the Tritons. Unless someone is building Norumphs with BSA C11 clutches
Title: Re: C11G clutch
Post by: Owen on October 10, 2019, 05:53:56 pm
Just to clarify. Up to 53 models had the 6 spring clutch assembly and taper shaft fitting. G, L, C12 ohv had 3 spring clutch assembly and splined shaft fitting.
Title: Re: C11G clutch
Post by: ianinglis on October 10, 2019, 09:30:06 pm
this is the basket you need - buy it - they are hard to come by and this is cheap
you can buy most of the other bits on ebay or from DRAGANFLY


https://www.ebay.co.uk/itm/bsa-c10l-daisy-wheel-sprocket/174051130523?hash=item2886417c9b:g:GwgAAOSwCRNdhy4n


ian
Title: Re: C11G clutch
Post by: chaterlea25 on October 10, 2019, 10:04:06 pm
Hi All,
Quote
One of the C series clusters is the same as an A series cluster
Not Quite  :o
While gear sets or gear pairs will transplant from one to another there are differences
The C box engagement dogs are a different design and the dogs are fewer in number
More importantly if you re rebuilding an A10 the material the gears are made from is different to the C gears
The A and goldie gears are all stamped EN36
Then again the Goldie gears can have different engagement dogs to the A

Damhik
John
Title: Re: C11G clutch
Post by: Ginge on October 11, 2019, 03:20:54 am
Someone’s done some work in that clutch basket Ian. 

Looks like they’ve welded a pressure plate to it?

Good price though.
Title: Re: C11G clutch
Post by: camman3 on October 11, 2019, 08:24:15 am
this is the basket you need - buy it - they are hard to come by and this is cheap
you can buy most of the other bits on ebay or from DRAGANFLY


https://www.ebay.co.uk/itm/bsa-c10l-daisy-wheel-sprocket/174051130523?hash=item2886417c9b:g:GwgAAOSwCRNdhy4n


ian

Yes....buy it...that is cheap and appears to be in good condition, you could easily sell it on if you end up with two.
Title: Re: C11G clutch
Post by: Steve P on October 11, 2019, 09:57:00 am
Thanks Ian
That's tremendous. I've been trawling eBay for a few weeks and totally missed this
Cheers
Steve
Title: Re: C11G clutch
Post by: Pat on October 12, 2019, 09:49:18 am
I have a NOS spring plate if you need it.
Title: Re: C11G clutch
Post by: Steve P on October 12, 2019, 09:56:37 am
Hi Pat
Can I hold off for a few days. I'm chasing a complete clutch at the moment.
I'll get back to you
Thanks
Steve
Title: Re: C11G clutch
Post by: ianinglis on October 12, 2019, 04:47:10 pm
when you search tinternet for these look for BURMAN clutch parts
the same bits where used on some AJS and MATCHLESS



IAN
Title: Re: C11G clutch
Post by: Steve P on October 12, 2019, 06:49:07 pm
Hi Ian
I  got the eBay clutch basket - thanks
Just all the rest of the bits to find now.
I'll try including the burman search thanks
Cheers
Steve
Title: Re: C11G clutch
Post by: johnboyfully on October 16, 2019, 11:35:14 am
Steve, I’ve got a new thrust washer PM me and we’ll sort it out JBF