1982 Sturmey Archer Dynohub AG electrical connector thread size?

Discussion in 'Bicycle Mechanics and Repairs' started by rrarider, 8 Feb 2018.

  1. rrarider

    rrarider Senior Member

    Location:
    Liverpool
    I've recently bought an old Raleigh Shopper just for local trips. If I should happen to lose one of the brass nuts connecting the wires to the hub whilst repairing a flat, what size replacement would I need?
    I think they are 4BA nuts but am not sure; can any one confirm my guess please?
     
  2. tyred

    tyred Legendary Member

    Location:
    Ireland
    I can't help you with the thread size but you should only need to unscrew the nuts a few turns to take the wires off for wheel removal. They are open connectors which slide on (assuming original Raleigh wiring).
     
  3. tyred

    tyred Legendary Member

    Location:
    Ireland
    The single most important thing to know about the SA dyno is that if you ever want to service it, DO NOT separate the armature from the magnets or they lose their magnetism and the power output will be much lower.
     
    raleighnut likes this.
  4. OP
    OP
    rrarider

    rrarider Senior Member

    Location:
    Liverpool
    I don't know how I missed this page when I first did a Google search for the answer:
    https://www.bikeforums.net/classic-vintage/1045861-question-about-dynohubs.html

    I was initially skeptical, as a tiny old spanner set that came with Lucas ignition parts (I think) has a 4BA version that just about fits; the 2Ba one is far too big. Looking at the fitted nuts, I see that they are steel, which must be the wrong material. They are probably some metric size, forced on. Measuring the OD of the brass male thread, I get 4.7mm with my vernier caliper, which ties with https://en.wikipedia.org/wiki/British_Association_screw_threads

    I think I'll risk a 2BA ebay purchase and hope that the steel nuts haven't chewed up the brass studs too much.
     
  5. OP
    OP
    rrarider

    rrarider Senior Member

    Location:
    Liverpool
    The 2BA nuts arrived and they fit perfectly.
     
    tyred likes this.
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