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How to remove the driving plate from my magneto?

Submitted by simon_amos on Fri, 17/08/2012
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I need to remove the driving plate on the magneto of my 1949 /ES2 as the stud has decided to detached itself. There appears to be 2 woodruff keys locking it and then I assume that the plate then can be unscrewed.

I am however at a loss how to proceed.

Any pointers would be greatly appreciated

Thanks

Ian

Submitted by simon_amos on Mon, 20/08/2012

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I have been told that if yoiu just " ... just gently lever the plate either side with a couple of screwdrivers ( the woodruff keys' remain on the shaft) and the driving plate then lifts off."

Alas, no success. I am a bit afraid to force anything through ignorance and end up damaging something. Its all part of the learning curve :)

The model is a regular MO1L

Regards

Ian (confused of Callington)

Previously wrote:

Well it can't be both keyed and screwed! I suppose you have tried using a puller? What's the model?

Submitted by andy_marks on Tue, 21/08/2012

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Is that the clutch type arangement that drives the dynamo? Suprised you need to take it off if it is. The way to do it is take the points and the other end of the mag off and GENTLY tap the armature out with a hyde mallet or similar. Before you tap the armature out of the body make sure that the pick up and earth brush have been removed as these will break the slip ring if left in.

The only problem with doing it this way is you will lose the magnetism as soon as the armature comes out the body. But unless you ar taking the armature out for a rewind anyway you shouldnt need to remove that plate.

Hope this helps

Andy

Submitted by simon_amos on Tue, 21/08/2012

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The stud on the driving plate has detached itself and I was hoping to remove the plate and re-rivet it in place. However, whilst waiting to remove the plate I have attempted to fix it in place by twisting it in tight and aralditing it in place. I know it is a botch, but it ceratianly seems VERY secure. I am tempted not to remove the driving plate and see what happens. If it comes loose again I will hear it rattling as before and will then remedy the problem correctly, as per your instructions.

Many thanks

Ian

Previously wrote:

Is that the clutch type arangement that drives the dynamo? Suprised you need to take it off if it is. The way to do it is take the points and the other end of the mag off and GENTLY tap the armature out with a hyde mallet or similar. Before you tap the armature out of the body make sure that the pick up and earth brush have been removed as these will break the slip ring if left in.

The only problem with doing it this way is you will lose the magnetism as soon as the armature comes out the body. But unless you ar taking the armature out for a rewind anyway you shouldnt need to remove that plate.

Hope this helps

Andy

Submitted by andy_marks on Tue, 21/08/2012

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That pin shouldn't be taking much of a load (if any) as long as everything is rotating freely. If it is all ok then your repair should be fine. But it might be worth checking your dynamo is revolving freely before putting it all back together.

Submitted by derek_ambler on Thu, 23/08/2012

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The old chestnut of de-magnetisation of the magneto on removal of the armature raises it's head once again!

Quoting from the Norton Maintenance Manual for the WD16H Magneto-"There is no need to put a keeper across the magnet as it retains its magnetic properties more or less indefinitely. Although it loses a certain amount of power in the first removal of the armature, subsequent removals do not affect it."

I should think by all MO1 magnetos must have been apart quite a few times by now; mine certainly have!

Regards

Derek Ambler

Submitted by andy_marks on Thu, 23/08/2012

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No doubt about it Derek. Once the armature has been out once it doesn't make a difference how many times it comes in and out. But if it was remagnetised after it was last put together, which it should have been if it was properly overhauled, then removing the armature will have the initial effect you describe. If the winding, condenser etc are all fine then there will still be enough magnetism in it to run and you probably won't notice a difference. But if the winding is starting to break down at all then the loss of some of the magnetism could make a noticeable difference.

Whenever we overhaul a mag, remagnetising is the last thing we do because then the magnetism stays up somewhere near what it would have been originally. Tho to be honest this is less important in MO1 type mags than ones with a horseshoe magnet as these really do lose the magnetism to the extent that a problem is caused when the armature is removed.

 


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