Hi all, I am trying to find a spare magneto to be repaired as a spare, I have come across a m01'6, 46020b. Would this fit my wm20?
Many thanks steve

email (option): Johnsonsteve386@gmail.com

Magdyno part no. 46020 (suffixes A-D) is listed for a number of post-war BSAs, including the 1945 - 1949 M20.

The M01'6 is the post-war type body with the 'cutaway' under the dynamo body.

...so it will fit and operate but, assuming that the tag is original, it will not look completely correct and 'in-period' for a wartime WM20 - but could easily have been fitted during post-war military service. Only you can decide whether the cosmetic aspect is a factor.

Thanks Rik, I can't find anywhere in the technical section what numbers I should be looking for or is there somewhere else I can get this information
Thanks steve

email (option): Johnsonsteve386@gmail.com

The correct mag for an M20 is an MO1/4 Anti clock rotation tight wire advance. Here is my reconditioned spare one dated April 45 (not for sale). Ron



Out of interest here is my spare "Slack Wire" mag (Royal Enfield) the body on the right is the post war type that Rik mentioned.

email (option): ronpier@talk21.com

If anyone has an M20 Spare Parts with additional VAOS LV7 list, it will give part number and description.

We had a go on an earlier thread and we Norton (and the RE chaps) produced quite a lot of detailed information (and I have reminded myself that in fact some M01'6 mags were late-wartime built.

http://pub37.bravenet.com/forum/static/show.php?usernum=3155626639&frmid=16&msgid=1372430&cmd=show

Rob Miller's research has shown that a correct wartime mag for an M20 should have an 'AC20' code on it.

As Ron has indicated, most wartime M20s seem to have had an M01'4 and I'd add to this that generally the part number seems to have been 465109 but more research and a broader sample is really needed before that can be taken as gospel.

This is probably a typical M20 mag.

Rik we might have been typing together when I edited with another picture.

But since you mentioned it, I've zoomed in on my 45 brass tag which quotes MO1/6 with part number 460105. It started life as clockwise rotation, which has been converted by my mag guy to AC. He informs me that the brass or ally labels were just turned whichever way is required for the rotation arrow.

Ron

email (option): ronpier@talk21.com

Ron, you had indeed edited whilst my back was turned !

Maybe at some stage they did simply reverse labels at Lucas but I have photographic examples of both early aluminium and later brass Norton AG4 labels which clearly show the clockwise arrow with the lettering the correct way up.

Must admit I've never studied it Rik. But I've got mags with labels both ways. In fact the two in the last picture of mine above are both "upside down" Maybe it was a trick by mag restorers? Ron

email (option): ronpier@talk21.com

Hi all, just wanted to say thanks for all the info, I have managed to get a m01.4 dated 7/43 with a brass tag, needs a rebuild but all the threads look good, I would love to post a picture but after a couple of hours I give up
Thanks again, steve

email (option): Johnsonsteve386@gmail.com

Finally!!!!!!!!

email (option): Johnsonsteve386@gmail.com

It's easy once you get the hang of it. That mag looks spot-on. If you tell the rebuilder what it's for, he can make sure that spec is 100% correct.

Now we know which type of body is the early one, what about the dynamo steel band. Ron's picture shows the steel band with external ears, if this dynamo is NOS then this type will be the early type. The later type then is the one with no ears and the fixing screw passes through the band internaly. If this is correct when did the later band come out was it with the introduction of the long 60W dynamo. So can we say that the 45W short dynamo has the external ears and the long 60W has no ears and the internal fixing screw.:confused:

email (option): t.j.walker@btinternet.com

While we're counting rivets, the dynamo brush band retaining screw on Rons spare magdyno is not of the original type. I'm not too sure about the pick up HT lead gland nut either...

Of more general interest, dynamo bodies were originally dull nickel plated..I've seen NOS brush band covers and dynamo retaining straps in both gloss and matt black finishes. For durability my personal preference is a gloss finish...Ian

email (option): ian@wright52.plus.com

Tim you have surmised correctly. The brush band on the war time 45W dynamo is like mine with the external ears. The post war 60W dynamo band has the through screw.

As Ian noticed my band screw and HT nut or not correct, which can all be put right with the parts already on my bikes if I ever need to use this spare mag or dynamo. Ron

email (option): ronpier@talk21.com

Thanks Ron,

I have my dynamo off at the moment and it has the external ears but a bit shabby i was going to replace it with the latter type. Now i will repaint the original one.

Ian,

The band screw on mine has a hexagon head with a screw driver slot in it. Looks original and chemical blacked. Cannot realy comment on the pickup HT nut but i would say its more suited to a G3L type magneto pickup. Tim

email (option): t.j.walker@btinternet.com

Again I think you are right Tim. I've replace that (BTH mag) pickup HT nut with a correct acorn nut, simply because one fell in my hand when I was rummaging in a box for a decomp lever, and the brush band screw is as you describe although more likely to have been plated. Ron

email (option): ronpier@talk21.com

Guys pack it in!!! I felt happy I got the magneto. I thought I've just got to find a dynamo and I am nearly home but now I find out even Ron has wrong parts fitted 😳!! What chance does a mere mortal like me have in getting the all the right screws, covers, etc 😂😂😂😂😂
Steve

email (option): Johnsonsteve386@gmail.com

['What chance does a mere mortal like me have in getting the all the right screws, covers, etc 😂😂😂😂😂']

None if we don't endlessly discuss it all...:laughing: :laughing: ...Ian

email (option): ian@wright52.plus.com