Fitting Triumph clutch to 53 B31?

[sprint]

A friend has a Plunger 53 B31 with an original 6 spring clutch that he wants to convert to a Triumph version.

Does anybody know if this can be done on the plunger B31's in the same way that it can be done on the A10's etc? Is the 6 spring clutch that is fitted to the B31' the same as that fitted to the A10's etc?

I have a 350/500 Triumph clutch assy that had originally been fitted by mistake to my RGS, 5 friction plate deep basket instead of the 6 friction plate basket, that could possibly fit?

Is the taper on the B31 mainshaft the same as the A10's?

Thanks

Andy

[JulianS]

A little information on this on the SRM product page for clutch - look towards the bottom of the page nder "note for pre unit singles owners" Might give a steer.


http://shop.srmclassicbikes.com/product/bsa-a10-a7-b3133-4-spring-clutch-pressure-plate-adaptor

[sprint]

Thanks for the reply and link. Sounds like there is a need for caution?

Anybody here who can enlighten a bit more or who has undertaken such a conversion who can offer some advice?

[KiwiGF]

At that price from srm you might want to investigate the price of a bob newby belt drive and clutch conversion.... see http://www.bobnewbyracing.co.uk/products.html

His web site is crap but product good, last I heard it was 450 gbp for a kit, that was e years ago tho.

[orabanda]

I fitted a Suzuki - based clutch to my B31.
The taper is the same as for the A10 (4 degrees), but there are dimensional differences between the shafts.

Tapered adapters I had prepared for A10 gearboxes went too far down the B31 shaft; the problem was resolved by starting with another (new) 4 spring adaptor, but machining it (the internal taper) much less in order to get the sprockets to align.

See pics attached.
I had to discard the SRM crankshaft nut, as it fouled the outer cover.

Richard

[chaterlea25]

Hi,
I have fitted a couple of 4 spring clutches to tin cased B31/33's
On one I spaced out the engine sprocket to get the chain line correct, on that one I had to reverse the sliding plate to get the scroll to engage with the sliding plate
On the second one a chance autojumble adaptor purchase lined the sprockets up perfectly
Yes, its a worthwhile job in my opinion
The 5 plate clutch will be fine for the B31
The adaptors from various sources and batches seem to have random taper depths 

The SRM adaptor with thrust washer that I fitted to my SR sat farther out than the one that was fitted previously
Luckily the new engine sprocket supplied had a shoulder on the inside, that got the sprockets in line (again  )

The thread I posted some while ago has some photos of the different sprocket shoulders and adaptor depth fits
https://www.a7a10.net/forum/index.php?topic=9646.msg70166#msg70166

I wonder if the tin chaincase has room for a belt drive 
Belt conversion on a B31 is probably overkill anyway

John

[sprint]

Thanks for the replies.

As indicated this is a friend bike, but it will me doing it if it is agreed/decided that it is doable?

I have a taper adapter and 350/500 chainwheel/basket which can be tried to see what sort of alignment problems there will/may be but don't want to go to all the hassle of removing the original clutch assy if it is a no-no from the start?

The indications are that it can be done but there may be a need to space the engine sprocket out a bit, but there may also be a problem with the pressure plate/adjuster fouling with the outer tin cover if the adapter sits high on the main shaft?

Are all the adaptor tapers the same, it just being a question of where the taper has been machined that will dictate where it sits on the shaft?

[chaterlea25]

Hi Andy,

Are all the adaptor tapers the same, it just being a question of where the taper has been machined that will dictate where it sits on the shaft?

All pre unit BSA tapers are the same angle
Triumph and unit BSA are steeper angle

John

[sprint]

Hi Andy,

Are all the adaptor tapers the same, it just being a question of where the taper has been machined that will dictate where it sits on the shaft?

All pre unit BSA tapers are the same angle
Triumph and unit BSA are steeper angle

John

Thanks John.