Have the main shaft adapter from Kidderminster to fit a Triumph four spring clutch. It stops on the step of the main shaft before the taper engages and needs to go another .010" to engage. So after turning the adapter on the lathe (the adapter is really hard steel!) to remove .020" it now fits the taper and locks properly. The adapter is for a WD M20 but am using it on a 1950 M21. I don't have a WD parts manual so am wondering is my main shaft different? And no my main shaft is not bodged up in any way and looks perfect on the taper.
So either the adapter was made wrong or not made for a 1950 gearbox without modification?????
Anyone else had this problem?
Bruce, I'm about to start the search for the necessary parts to do the same Triumph clutch conversion to a WW2 M20 box in my Indian special. I have noted that Kidderminster has the adaptor, but waiting to contact another firm that Ian advised. (They've been shut for a week). I'm not sure though if they are all made by the same firm? (L Harris). I also don't know if the main shafts are the same although I've heard Ian say the internals are the same to a point (He's also away, back soon).
I was hoping for a reasonably straight forward fit! Did you by any chance contact Kidderminster about the issue? Ron
PS the WD part list number for the main shaft is 66-3283.
email (option): ronpier@talk21.com
I had a clutch and adaptor from Kiddiminster a few years ago and had no problems fitting to a plunger B31.
afaik the mainshafts are the same on all the plunger / rigid boxes except the 1946-48 which will only accept the 6 spring clutch.
when Ian returns from galivanting around the country we will get a definitive answer I am sure :laughing:
email (option): petercomley@web.de
The standard BSA/Triumph adapter 42-3170 is for the A and B models. The taper on the M model is different and requires the rare adapter which I think is only made by Harris. As you say, Ian will know. Ron
email (option): ronpier@talk21.com
My 1949 M33 bitsa has the gear box with the speedo drive. When I bought the bike it had the single spring clutch fitted. I removed this and fitted a standard six spring clutch and the adapter fitted with no problems. I would have thought that the Triumph clutch adapter would have fitted also.
email (option): ian.clare1@virgin.net
Ron,
The part number for the main shaft on my 1950 rigid M21 is 15-4260 and you stated the WD one is 66-3283. Are they the same, who knows???? I thought the only difference between late and early M series bike gearboxes was the outer cover and clutch.
Anyway after turning off .020" from the clutch adapter, it now fits and the crank and clutch sprockets are close to being in alignment. And more importantly the taper now locks solid and takes a good bit of force to brake it free.
So are the main shafts the same for all the M series bikes, I am guessing they are not.
Bike should be back on the road in a couple hours! Only bad thing at the moment is it is 104 degrees F so will be a hot ride!
Bruce
Bruce, I recently fitted a 4 spring Triumph clutch to my 1941 WM20 with an adaptor ordered from Kidderminster. When ordering they particularly asked for the year & model of the BSA the adaptor was for. I have had no problems fitting or running the clutch.
email (option): grcajol@bigpond.com
Greg,
Yes I did state the year and model to Kiddermister when ordering the adapter. The fact they asked would indicate there are differences in M series main shafts? Or perhaps they sent me the wrong one? Anyway after modification it now fits.
Bruce
Is this the same adaptor that is available from Draganfly?
email (option): ronpier@talk21.com
Presumably the adapter doesn't just have to fit the clutch and shaft it also has to put the clutch in exactly the right place so the chain lines up with the front sprocket?
Rob
email (option): robmiller11(a)yahoo.co.uk
That is exactly the purpose of the correct adapter Rob. On Ian's Recommendation I've just ordered a complete clutch from Monty's Motorcycles in Cornwall. He has the correct adapter same as Kidderminster but much cheaper. :+1: Ron
email (option): ronpier@talk21.com
Fitment of the clutch adapter is the same for all rigid and plunger B and M models using the wartime or post war heavyweight gearboxes and they will all accept the same adapter (if correctly manufactured)....
The confusion is caused by the fact that the original adapter (a BSA part) was manufactured by BSA to enable them to fit the Triumph clutch to their swinging arm models.... It is therefore not suitable for the earlier models...
The reason it is not suitable is that although the taper angle is the same on all the boxes described above, the taper diameter is not...The swinging arm gear box taper diameter is smaller. So, when that adapter is fitted to an earlier type box it doesn't go far enough onto the shaft...That causes a misalignment of approx. 1/4" between the engine sprocket and the clutch sprocket with the clutch sprocket being further 'out board'...
For years the trick was to increase the width of the spacer behind the engine sprocket carrier to realign the sprockets and then to fit a slightly shorter (worn!) shock absorber spring...
In response to demand from customers L F Harris, and possibly others, eventually produced the adapter with a modified taper diameter to make it a 'direct fitment' to the earlier boxes, thus removing the need for any modifications regarding sprocket alignment...
This later adapter was never a BSA part and carries no BSA part number, its description only being defined by its application to the earlier models...Ian
email (option): ian@wright52.plus.com