• grahamsmythe
    4 July 2017 at 12:15 #52416

    First off, thanks for letting me join your forum.

    At the weekend, I bought a B.T.H magneto which at the time I thought was a mag-dyno and would be suitable for my pre-war Vincent motorcycle.

    It turns out that it’s not the right one at all, and it’s been suggested that it’s a dynamo suitable for a Lagonda car.

    Can anyone here help me identify the model and cars that it might be suitable for?

    Look forward to receiving any suggestions.

    Many thanks.


    Attached files

    21 July 2017 at 09:11 #52425

    Are there any identifying numbers stamped on the body?
    Best Regards

    21 July 2017 at 09:21 #52426

    It looks like B1377

    Attached files

    21 July 2017 at 09:25 #52427

    I forgot to ad it looks like an early GA4 model, but which GA4 I don’t know.
    I think Riley, Alvis and other marks used them.
    I have seen a couple of BTH magnetos on 2L Lagonda’s but the preferred choice was always a Scintilla.
    That was until after 1933 when Scintilla refused any further credit to Lagonda which is where I think BTH stepped in.
    Let me know what serial numbers, stamped casting numbers you find and I will see if I can identify it for you.
    Best Regards

    Colin M34
    22 July 2017 at 09:28 #52428

    Hi Chris,

    I think you are correct about this being an early GA4 model. I don’t think it was used on a Lagonda – it may have been used on something like a Bullnose Morris.

    Regarding 4 cylinder Lagondas, I have seen BTH, ML and Scintilla used. I prefer ML because it is a rotating magnet machine. Rapiers seem to have used BTH and as you say, late 2 Litres use Scintilla – as do 16/80s.

    M45s use a mixture of BTH and Scintilla and I have clamp bars for both.

    Now for a laugh. I agree with you that magneto suppliers probably refused to provide any more units until they were paid. I suggest they were ordered in fairly large batches – say 100 to 150 at a time, and when BTH refused further credit they turned to Scintilla and vice versa. So when the 16/80 was launched they had enough Scintilla PN6s to cover production for a year or so but then they did not pay the bill so had to go to BTH for the Rapier and M45.

    As a company verging on insolvency it must have been a nightmare working out who to pay next to keep production going. No wonder the salesmen were encouraged to get deposits from customers straight away.

    Cheers Colin

    27 July 2017 at 12:09 #52429

    Hi Colin,
    Well I most certainly would not have done business with them.
    Best Regards

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