B31 clutch

[DEDGE]

Hi Guys
More help with my 1950 B31 plunger rebuild please. The clutch was a mess of bits when I got it so dummy run putting it back and lining it up.
Picture shows the clutch sleeve goes up to drive sprocket net, book says should be felt and cork washer there ( sleeve oil ring collar not on there yet).
Does anyone know the length of main shaft from sprocket nut to shaft end Picture 2
Have I got the wrong main shaft (the gearbox seemed right) or the wrong sleeve or just doing it all wrong
Picture 3 view of drive sprocket.
All The Best
Dedge

[GBonduel]

You seem to be doing OK, I'm guessing you're using this diagram:

Don't have the exact measurements but I do remember it looks too short but once everything is assembled it works.

[DEDGE]

Hi Guy's
Still trying to sort out my clutch, as to whether the main shaft is wrong or the clutch sleeve. Both look right by looking at parts book pictures. But the clutch sleeve slides on and of by hand  and not wedge on the tapper. The 1949 parts book list it as 66-3799 and the picture looks the same but dragonfly list it as
65-3873 and again the picture looks the same does anyone know if theses two part numbers are the same.

Dedge

[JulianS]

The 1948 1949, 1950 and 1951-52 all model parts books all show the clutch sleeve as 66 3799, the mainshaft as 15 4260 and spring frame chaincase back as 65 7578.

The B series 1949-53 book shows the sleeve as 65 3873 with the mainshaft and chaincase back remaining the same part. So the sleeve does interchange. The mainshaft goes back to the 1930s.

The 1948 engine plates were different parts to the 1949 and later but I dont know what the differences were.

[Dan_B33]

Think I have same problem. What was the sillution?

[neil1964]

Think I have same problem. What was the sillution?

You are not the first to have this issue.  The M20 and early box types and 51 plunger are all different afaik. I only have s/a boxes but suggest read this:

https://www.britbike.com/forums/ubbthreads.php/topics/871155/re-finding-the-right-clutch-package
I also suggest you read this:
https://www.britbike.com/forums/ubbthreads.php/topics/674773/bsa-6-spring-clutch#Post674773

[cdsdorset]

Do you have the earier gearbox fitted. Where is the speedo drive mounted?

[Dan_B33]

Here is teh gearbox I think it is later version.

[Dan_B33]

Main Shaft is like that on picture

[Dan_B33]

And picture

[Dan_B33]

Clutch sleeve is in matching shape but the fit is not tight

[cdsdorset]

You may have the earlier gearbox sleeve ( pretty rare now) virtually identical but the internal taper is a different angle.

[Dan_B33]

Thanks cdsdorset,
I'll compare with sleve I've brought on eBay. I hope they differ an that the one from eBay fits...