Hazel's Place

Hazel's Place
Picture modified by Pete C (W650 rider)

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Monday, 16 May 2011

BSA 6 spring clutch

I'll soon be re-assembling the clutch on the B31 so I'm looking for any useful information to help me with it.  All I have at the moment is the exploded diagram in the parts book so I don't have any info about tolerances or how tightly things need to fit together etc.

I've found some useful advice here:

Clutch assembly

Clutch set up

Clutch plate adjustment

BSA Service Sheet 308

Tips for oil tightness

More Googling needed!

If anyone has any more info/diagrams/instructions I would be most grateful!


  1. Hazel, have you tried the BSA group on Yahoo?
    I've seen discussion there a few times about Triumph clutches in BSAs. Could ask Dave Hopwood who's on FB...he may know about it or someone who does.

  2. I may well join the BSA Yahoo Group, always found the W650 one to be helpful.
    I'm told (by Classic Bike's Rick P, among others) that because mine is a 1946 model, the Triumph clutch can't be fitted - different gearbox mainshaft means the clutch centre doesn't fit. That's a shame, because I'm really impressed with the Triumph clutch in the Tribsa. I was thinking of asking on FB too. Thanks.

  3. Ahhh good stuff to know, got a 1960 BSA B-33...so a Triumph clutch might fit my bike? I didn't work on much Pre-unit stuff as a mechanic, so I'm still learning a lot there.I should check out these groups. I was told my 60 was a good one because it's a points/alternator model. Lot's to learn and it's good to be able to pick others brains for info.

  4. From my limited knowledge I think you probably could fit a later triumph clutch. I think it was only 1946 that had the wrong shape shaft. It wasn't difficult to fit one to the ex's B31 and very easy to set up nicely. Cost was about £300 so possibly something you would only do if you really didn't like the 6 spring clutch. The Tribsa clutch probably needs a bit of adjustment now but when I first set it up it was lovely and light.
    Any info I get on the 6 spring clutch will be collated on here and I'll try and do a step by step guide when I assemble it (and possibly re-assemble again and again until I get it right!), just in case it might be of use to anyone.

  5. I've only gotten as far as removing the top end, and it needs complete re-doing. The Crank as well needs help. Did'nt get as far as the clutch yet, so we'll see if it needs help. Judging by the condition of the rest of the motor it won't surprise me if it's shot. That would be a great thing for you to do, gathering up all the info. I probably have a spare Triumph clutch around I could fit to the BSA.Seems somewhere I saw where someone was putting a Suzuki clutch conversion into BSA's.

  6. At the shop I worked at...if the boss saw someone doing multiple assembling on a project...he'd say " I see you are taking it together", and walk off shaking his head....

  7. hi!
    im also wanting to do a B-33 clutch conversion! im excited to learn more:)