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Thread: Dating Bosch Mags - Calling All Magneto Guys (and Girls)

  1. #1
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    Default Dating Bosch Mags - Calling All Magneto Guys (and Girls)

    Hi all, I have been trying to find dating information on Bosch magneto's. I have searched this site and on the wider web and the few books I have on older stuff and I can find some information about serial numbers from 1902 to 1915 but thats all. We know that Bosch magneto's were in use well beyond 1915 but I cant find any serial number information after that year.

    Also, Bosch Magnetos were built in Germany and the USA so are there two series of numbers or did Germany and the USA co-ordinate to use the same series and allocate numbers to each side of the Atlantic? (at least outside of World War I).

    If I have missed some threads on here then apologies in advance.

    John

  2. #2
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    I am looking forward to some knowledgeable replies, John. Bosch was supreme in magnetos and I would like to know more about their chronological contribution to American motorcycling I know we have members that know a lot about this subject.
    Eric Smith
    AMCA #886

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    some good infos are collected here:

    http://www.go-faster.com/BoschMagnetoVeteran.html

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    I can speak to some Harley history I suppose. I'm not expert just a fella who can't pass up a magneto when the price is right...

    There's no serial number data post 15 from what I've seen too. Probably due to WWI and how pissed off everyone was at Germany post war. America took over the US Bosch operations and started making "American Bosch". From what I hear they are fairly subpar in quality compared to the German version of the same thing. I've seen a few ZEV American Bosch Mags, they have different font on the casting and look just a little weird. Post WWI a lot of magnetos were shipped from Germany as "Robert Bosch". Post WWI electric models started coming into play and surpassed the old Mag orders so most mags are from the prewar era. They made a ton of motorcycles as we know pre 15' and the magnetos were the next most valuable thing to the engine on those bikes so I'm sure they were pulled before they hit the scrap pile. ZEV's are built for the desired firing degree and usually have the degrees stamped on the armature, aluminum case, and cam to make sure they stay together.

    For Harley, you could order a F model up with a ZEV up to 26'. 27 to 31 or so they produced the FFVRS model (Harley references building magneto model VL's called the VM. I've never seen one though). This isn't a mag specifically designed for the armature height of the US domestic market and was probably designed for European manufacturers. A 1/4" lift plate is required for use on Harley, Excelsiors, Indians... These mags are used on all sorts of fancy bikes from europe. There's a great dual plug set up somewhere on the Vintagent with two of these FFVRS magnetos chained together. These mags do create a heck of a spark but are not really superior in everyday use to a ZEV. I believe they are easier to work on as the brush towers are easily removable and the wires can be swapped out in a matter of minutes without removing the magneto from the bike. I've seen these mags adapted for use of 45's. Famously the most valuable model is for the DAH, although the few I've seen don't even have this magneto fitted and use a later FFVA.

    I have an early 30's Japanese copy of a FFVRS magneto on my J and it works fantastically. Converted from a single cylinder to a twin.

    Post FFVRS the twin magneto Bosch offered was the FFVA / FF2A, released in the mid 30's. Perhaps earlier. The brush towers on these mags are the hardest to find and a real headache to make. These seem to be a popular, and probably available in the 30's from a dealer, to run. I don't know if Bosch made magnetos for American motorcycles after that. WW2 probably really nailed the coffin shut there and of course Harley had already moved on...

    Overall most magnetos are not motorcycle magnetos. There are heaps of single cylinder magnetos compared to one twin cylinder, there were a lot more stationary engines made than motorcycles I bet. Even more 4 and 6 cylinder mags for planes, cars and farm equipment. Finding twin cylinder cams for the later model magnetos is quite difficult. There is a company in Germany repooping quite a few of these hard to find parts though.

    Hopefully I explained some history and did not muck it up too bad.

    John, I hope we see more of your J. I really enjoy the detail you bring to this forum.

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    Quote Originally Posted by gsottl View Post
    some good infos are collected here:

    http://www.go-faster.com/BoschMagnetoVeteran.html
    gsottl, I have followed that website for quite a few years and have seen the great info gathered there on Bosch Magneto's.

    I have emailed Paul and asked him for the contact info for the Bosch Historical archive that he mentions as I cant find any information on what it is. Hopefully I will be able to contact them and see if we can fill in some of the post 1915 gaps.

    Ironically the company that I work for own Bosch and I have tried contacting Bosch directly although so far I have just been given stock answers and links to their website.

    John.

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    Quote Originally Posted by whp View Post
    I can speak to some Harley history I suppose. I'm not expert just a fella who can't pass up a magneto when the price is right..
    Hi whp, me too which is what prompted this question. I have recently picked up several mags for a good price including 3 Bosch ones. One dates to 1907 but the other two are post 1915 so I cant nail them down. This post might finish in a dead end but lets see if we can fill in some of the gaps with a bit of effort.



    Quote Originally Posted by whp View Post
    John, I hope we see more of your J. I really enjoy the detail you bring to this forum.
    Thanks for the compliment. Hopefully there will be more soon. I have another build on at the moment but I am hoping to do a bit on the 20F at the end of March.

    John

  7. #7
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    I got information from the Bosch Archiv years back, but it seems this now is part of "Bosch Classic" http://www.bosch-classic.com/de/inte...__contact.html

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    Quote Originally Posted by gsottl View Post
    I got information from the Bosch Archiv years back, but it seems this now is part of "Bosch Classic" http://www.bosch-classic.com/de/inte...__contact.html
    Thanks for the link gsottl.

    I have also found the Bosch History Blog here: https://blog.bosch.com/history/en/

    I will see what I can find out next week by contacting them. The authors seem to have good access to historical Bosch records and information. At the least it would be nice to find out is post 1915 information exists.

    John

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