Magdyno MN2 Problem

[douglas1947]

Some years ago I have bought a MN2 magneto for Douglas T35.
Now I want to use it for my 80+ project and gave it to overhaul and it came back with perfect sparks. I wanted to fitit to my 80+ engine but I was not able to fit the magneto gear to the shaft  -  shaft too short or conic hole in the gear too big. The gear will not fit the shaft and is scaping the crankcase.
Now I got a new mag gear, but the hole is the same as in the old one, comming with the magneto. So I think the drive shaft of the armature is too short (around 4mm).
 
May be the magneto had a wrong armature when I bought it? I found out there are different numbers for different magdyno types:
 MO1 - 464205 and MN2 - 463283.

Has someone any experience with these magnetoes?
I do not know, what to do next.

Michael

[eddie]

Michael,
            The timing gear on a 'Plus' magneto is different to that on a Mark. The 'Plus' timing gear has a dished centre giving the extra clearance. The standard drive gear for the Mark magdyno is part number 32541. The 'Plus' drive gear is part number 37726.

  Hope this helps,
                           Regards,
                                        Eddie.

[douglas1947]

Eddie,

thanks for the explanation. So the good news is: my  MN2 is okay!

So I have to search for a Plus Mag Pinion. Do you have any idea?

Michael

[veikko1]

Hello

New knows to my also. Thanks Eddie! I need also Plus pinion....

Regards
Veikko

[douglas1947]

Hello Veikko,

my idea was to ask you for a spare Plus mag pinion today!
So I save the question.
Do you have also only a MK gear?

Michael

[LENBOY]

Just seen this section and notice that Michael mentions he acquired a T35 magdyno, be aware that the plus models magdyno is different to a standard Mark series. I believe that the standard mag body can be modified to fit but I am not qualified to recommend this, not having done it myself. . Best wishes to all Douglas owners. Len.

[eddie]

According to my Lucas catalogue, T35 & Mk3 machines were fitted with an MN2 magdyno (part no. 46021D). Later Mks and 'Plus' machines had MN2L magdynos (part no.s 46027D & 46040A/B) - the 'L' suffix denoting the fitting of a long dynamo. There was, of course, the option of a K2FR magneto on the 'Plus' models for racing use (part no. 42206A/J).
  The list doesn't mention the physical differences between the various models.
  An unusual feature of the magdynos fitted to postwar machines is that they are configured to have 'tight wire' advance - the only postwar Douglases that I have come across that have 'slack wire' advance, are the three ISDT machines that were made for the 1950 event. They are fitted with Lucas 'Competition' magdynos (distinguishable by having the advance/retard cable going into the opposite side of the mag!

  Regards,
                Eddie.

   P.S.  I have had another look at the parts book, and the magneto sections of the 2 MNL2 magdynos have different part numbers, but the only internal difference that is listed is the width of the Tufnol drive gear on the magneto armature. All the other part numbers are listed as being the same across the 3 models fitted to our postwar machines.

[cardan]

Hi Eddie,

A bit off topic, but your post gets close to something I've long wondered about.

Presumably the mag-dyno is the usual platform-mount affair, but does the K2FR magneto on the racing Plus use the three-bolt flange mount? If so, are all Plus cases pre-machined for the flange-mount magneto, or just those intended for racing?

Thanks

Leon

[douglas1947]

Leon,

on all Plus models are bores / threads for MN2 and k2f magnetoes on the crankcase. The hole for the drive is smaller than on MK models, to take the stepped flange of the K2F magneto. Fitting of the pinion to the magneto works only from drive side, so you have to fit first the magneto and the pinion seperate.

I add a photo of the (uncleaned) 80+ crankcase.

[cardan]

Thanks Michael - now I know!

Leon