Is there a conversion for plunger clutch

[muskrat]

G'day Fellas.
I'm of the thought that it was all a cost cutting exercise. The semi unit clutch would be far more expensive to produce.
I luv the clutch in my plunger. Light, smooth and doesn't slip or drag. I last replaced the friction plates and rollers 30 years ago. Anytime I'm in the primary I set it up with a dial for even lift.
The clutch in my Cafe is a Notrun diaphragm type with dry belt drive. Soooo light one finger but does squeal a bit on spirited take offs.   
Cheers

[Jules]

thanks Swarfy, now I understand it better, I agree with Muskie, definitely a cost cutting exercise!!
Quite an invention was the diaphragm clutch back then, revolutionised clutch feel and performance in cars at the time, you just had to "feel" the bite point a bit better because then it was "in" and you were off! cheers

[Black Sheep]

Much though I love our '59 A10, I think our '51 plunger Star Twin was a better engineered machine. Proper QD wheels, excellent brakes, semi-unit gearbox, better clutch, duplex primary chain. T all went downhill after that. 

[Rex]

My '51 plunger Star Twin has a 7" front brake, something I'd never describe as "excellent"..

[Greybeard]

Much though I love our '59 A10, I think our '51 plunger Star Twin was a better engineered machine. Proper QD wheels, excellent brakes, semi-unit gearbox, better clutch, duplex primary chain. T all went downhill after that.

I agree.

[BSA_54A10]

Back in the day the go was to rebuild swing arm boxes with plunger mainshafts to use the substantially better clutch .
Never been able to verify it but my gut feeling was BSA was too busy at the time so the clutches & boxes for the plunger A series were bought in as a unit .
Apart from the A 75 & Bantam BSA clutch tapers are the same from 1916 through to the A 65
The bantam uses a splined shaft because that is what was shown in the plans and the A 75 will not hold on the std BSA taper
There is no bolt on conversion
To do it you pull the box then swap the mainshafts
From memory it is almost a direct swap apart from the thrust washers & the kick start ratchet .

[JulianS]

I am aware of the conversion of the swinging arm box by fitting the splined plunger mainshaft to fit a Norton clutch.

Eddie Dow had them in his 1967 catalogue.

[BSA_54A10]

I am aware of the conversion of the swinging arm box by fitting the splined plunger mainshaft to fit a Norton clutch.

Eddie Dow had them in his 1967 catalogue.

Yep
From memory the Dow mainshaft was slightly modified so it went strait in
The std plunger mainshaft needed a bit of fitting to get it to sit properly
Done it once and am looking at doing it to the M20 which requires a bit more fitting as well