The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: Keith on 28.06. 2013 11:35

Title: What clutch have I got?
Post by: Keith on 28.06. 2013 11:35

Hi all,

I bought an old tribsa that I have stripped and am now gathering the parts with the intention of building an ISDT type A7 as I always fancied one. One of the many queries that I have is, What clutch do I have at the moment.

It is a four spring unit, 4 friction & 5 plain plates, non cush centre and the hub fits on a plunger BSA mainshaft.
The inner plate is about twice as thick as the others and has a step on one side of the centre. The 3 centre plain plates are also thinner than the outer one. Thicknesses are inner 140th, 3 middle ones 65th, outer 90th.

Anyone know what it is if so is it worth keeping.

Thanks, Keith.

http://i482.photobucket.com/albums/rr189/dfor_photos/Tommy/IMG_2928_zps3c9fed15.jpg

http://i482.photobucket.com/albums/rr189/dfor_photos/Tommy/IMG_2954_zps3c78f2f3.jpg

adm edit: img tags removed. See http://www.a7a10.net/forum/index.php?board=15.0 for rules about posting pictures. Thanks.

Title: Re: What clutch have I got?
Post by: Brian on 28.06. 2013 12:11

Hopefully someone can confirm this but I think its a NotRun clutch, as far as I know they are the only one that will fit the plunger splined shaft.

Even though it comes from "that" make of motorcycle I believe they are quite a good clutch.

Title: Re: What clutch have I got?
Post by: Keith on 28.06. 2013 13:08

Hi Brian,

You could well be right but as far as I can tell from all my searching the Noton clutch has much larger tangs on the friction plates. All the ones I found were 3 spring as well.

Keith.

Title: Re: What clutch have I got?
Post by: chaterlea25 on 28.06. 2013 22:36

Hi Keith,
No its not a Norton clutch, its BSA / Triumph basically ( I think?)
Its just thet it has a special centre that fits the splined mainshaft
Also different is the inner clutch drum
I have neverr come across one before??????
Indeed it does away with one of the common problems on the A7/10 bikes bypassing the often troublesome taper adaptor
I mentioned here the other day about clutches having thicker innermost plain plates as on Burman boxes (Ariel, AJS/Matchless) but these are normally 5 spring
The splines between centre and drum resemble Burman???
Does the splined adaptor come away from the bearing/thrust piece?

Regards
John

Title: Re: What clutch have I got?
Post by: madsens on 29.06. 2013 08:37

Hi All

As I have my engine out for a total overhaul I just enclose 2 pic of my clutch for comparison.

I'm not sure if it's a standard 4 spring BSA/Triumph clutch?  It's got 6 friction and 6 plain plates - seems an awfull lot? but it was working alright, but a bit difficult to find neutral if stopped.

regards
Joergen

Title: Re: What clutch have I got?
Post by: Keith on 01.07. 2013 08:41

Hi all,

Thanks John and Joergens.

Yes the splined adaptor does come away from the bearing piece John. In fact as it's shown the 2 top pieces come off the adaptor.
For info as well there are 24 rollers.

Joergens, it does look very similar to yours but the main thing that put me off was that all the pictures I've seen of the BSA/Triumph clutches they have 10 tangs on the friction plates and mine only has eight.

Keith.

Title: Re: What clutch have I got?
Post by: BSA_54A10 on 06.07. 2013 11:30

The plunger A 10's used clutch that ran on the splined main shaft and is unique to the plunger models.
It is a direct copy of the Burman clutch ( as used by every one other than BSA -Triumph )thus AMC clutches are interchangable as is the late Commando.
Why BSA did this is one of those mysteries lost in time.

Title: Re: What clutch have I got?
Post by: Keith on 11.07. 2013 22:10

Finally identified it.

Its a Burman CP.

John you were almost there. I think the later B52 clutch is 5 spring. The different widths of plain plate is also normal and all parts are still available.

Anyway thanks to all those who helped.

Keith.