Magneto woes

nkt267

nkt267

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Hello John, Are you sure the bearing was at fault,
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Hmm.. This problem is a bit like ' chicken or egg first'.
I have been thinking about excess crankcase pressure causing oil to be pushed through the seal(this is also pointed out in a magneto service manual) I am experimenting with a crankcase breather at the moment, but I don't think I have made it big enough yet. Interestingly the breather on my 600cc 1932 Sunbeam only has a 1/4" breather and that seems ok.
Either way the fit of the bearing has to be addressed first.If I can find a decent body then I will go in that direction,though I have found someone selling a mag for a Comet so I may buy that anyway.
I will continue to repair the mag body as the knowledge I gain may help someone else in the future..John
 
nkt267

nkt267

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VOC Member
If you have too many shims under the cam housing it would give you the same problem
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I don't quite follow your thinking on this point. If there are too many shims under the cam housing but there is no endfloat in the armature how is the relationship between the oil seal and it's seating on the taper affected?.
Surely the drive end bearing fixes this dimension..John
 
Bill Thomas

Bill Thomas

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Sorry, I did not see the bit about no end float, I was thinking, Maybe the oil got in, Then the insulating washers perished, Nobby is trying to sell a mag, If your stuck, Cheers Bill.
 
nkt267

nkt267

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I think I have found a fairly easy repair for my magneto drive end bearing.
A standard E15 bearing is 15x35x8mm.An N3048 bearing is 15x37x8mm.Thanks to Howard for pushing me onto the simply bearings web site as I did not think that there would be anything there to help me.
My thinking now is that all I have to do is machine the mag body to accept the new bearing, and as the inside diameter of the outer race is the same as the smaller E15 bearing it will retain the seal as per the original.No inserts or other special parts needed..
Picture at the end of this link http://www.vincentownersclub.co.uk/photos/showgallery.php?cat=500&ppuser=245
John
 
nkt267

nkt267

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VOC Member
Last edited:
nkt267

nkt267

Well Known and Active Forum User
VOC Member
The mag is now back together and has a nice healthy looking spark.All I need to do now is get a new piston, get the barrell rebored and find out if the mag is ok on a good long run..John
 
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