Rebuilding my single spring clutch I opted to replace the rollers. Draganfly lists the part # as 26 - 650. They also say this part was superseded by rollers of 1/4 by 15/64.
The existing rollers are 1/4 by 1/4. They seemed to allow quite a bit of back and forth play (along the axis of the main shaft).
I ordered a set of rollers from a different source, with the part # 26 -650. They are 1/4 by 5/16.
Ian Wright on this forum says the size should be 1/4 by 1/4, and I'm inclined to trust his expertise.I thought I'd better make sure, though, before sending a note to the supplier of the 1/4 by 5/16 rollers.
1/4" x 5/16" rollers are the size for the big end...I haven't heard of the 1/4" x 1/4" clutch rollers being superceded but I don't claim to know everything!...Some documentary proof for that assertion would be interesting...
I'd have thought another part/specification would usually mean another part number to avoid the possibility of mixing parts, yet the 49-58 parts list shows the same number as the WD models...26-650...
Triumph clutches did use a slightly shorter roller, perhaps Draganfly have their wires crossed?
Frustratingly, the post war REME M20 standards book (the reference book used by REME for full overhauls) lists the roller diameter only (1/4"), not the length ...Ian
Thanks so much for this, Ian. It's most helpful. I think my supplier must have the part number wrong, so I'll send an email to him. We can't have more people getting bewildered!
The source for the 15/64th measurement is on the Draganfly site, when you go to buy the 26-0650 rollers, there it is next to the price and the small picture.
The part number is 26-650. Drags have changed theirs to 26-0650 which is automatically superseded by T527 which looks like a Triumph part to me.......One size fits all? Ron
You are correct. Draganfly's parts diagram shows the rollers as 26-650, but then on the 'buy it' page the number becomes 26-650 and 26-0650 and also has T527 as their substitute; dimensions for that are given as 15/6.
A search through parts sellers has Feked listing 26-650 and 26-0650 as identical, but as measuring 1/4 by 5/16.
Peter's Classic just lists 26-0650 for the m20, at 1/4 by 5/16.
Classic motorcycle has the same.
When I place the 5/16 rollers against the clutch inner sleeve I can see they are too tall for the bearing surface.
Bit of a typo there Allan! Drags give the length of their rollers as 15/64". It is very important to have at least 12 thou reduction in the 1/4" length for some Triumph models, as I learnt the hard way on my 38 Speedtwin. But to my knowledge it's standard 1/4 x 1/4 rollers in an Empire Star type clutch. Ron
Ooops - you're right about the typo, Ron. Many apologies. 15/64 is what it should be - and I think the extra clearance would be important, too, from the sound of your experience with your Triumph..
I'm going with 1/4 by 1/4 rollers for my wm20. Just have to wait for them to arrive.
Without trying to sound like an expert I'm sure 1/4 x 1/4 are correct for M20 clutches. 1/4 x 15/64 are the size used in Burman clutches on Matchless etc.
Richard
