BSA Owners' Club Workshop Discussions

The BSA Workshop => Twins => Topic started by: Superflash on 27 Jun, 2026, 01:37

Title: A10 Plunger upgrade
Post by: Superflash on 27 Jun, 2026, 01:37
Hi, does anyone do a belt drive or 4 spring clutch upgrade kit for 53/54 plunger models? Everything I've found are for S/A models only. Would like to get rid of this 6 spring clutch if I can. Cheers
Title: Re: A10 Plunger upgrade
Post by: V500 on 27 Jun, 2026, 09:10
Good clutches. Why the desire to get rid?
The 6 spring B series clutch I can understand the need to change, but the A series plunger clutch?
Title: Re: A10 Plunger upgrade
Post by: limeyrob on 27 Jun, 2026, 09:57
I did many miles on a plunger A10 with a 6 spring and chain.  Worked very well. Its actually a better primary drive than than a later SA.  These drives and clutches are good for 70 years with regular servicing.  The key to the 6 spring is replacing a worn centre and filing any wear off the plate tangs and basket.  I would not see a belt as an upgrade on a plunger.
Title: Re: A10 Plunger upgrade
Post by: EDDIE SIMPSON on 30 Jun, 2026, 00:06
a norton commando clutch chainwheel drum may work, but the space is tight on the plunger chaincase side.
i agree that the standard plunger clutch is good enough  normally and without the wearing shock absorber  like the a65.
Title: Re: A10 Plunger upgrade
Post by: Superflash on 30 Jun, 2026, 06:43
All good. Thanks for the opinions. I'll just have to continue trying to sort it out.
Cheers
Title: Re: A10 Plunger upgrade
Post by: DAVE BRADY on 30 Jun, 2026, 14:07
Hi,

The plunger 6 spring clutch is superior to the SA frame 6 and perhaps even the 4 spring.
Duplex chain, roller bearings, slipper tensioner etc.

Over 120,000 miles covered.

Dave.