Magneto Drive Gear assembly problem

[Andy Cawley]

I am reassembling my magneto engine after breaking the crank and am fitting a new 1 1/8" Pheonix crank. I had quite a delay waiting for the crank and the memory has faded of the disassembly and I'm having difficulty remembering precisely how it all goes together and also whether or not any bits were missing when I took it all apart.
My current puzzle is the importance of item BB34  described in the spares list as a plate. It appears the purpose of this item is to protect the ball bearing from the magneto felt oil seal.

 I cannot find the plate in my box of bits  .

I will probably have to make one but I have no information as to the dimensions and looking at the picture in the spares list it is not exactly a simple disc of uniform thickness.

Can anybody help out.

I would have posted a photo but couldn't work out how to, sad isn't it?


Could I just fit a sealed bearing and leave out the felt seal. If I did this would I need to make a spacer to replace the felt seal ( I have bought a new seal)?

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[bob46320]

That is the oil thrower ? I think you mean replace the felt and thrower with a modern seal. Unless you propose to replace the plain bearings as well.

[Andy Cawley]

   

Does the plate fit into the larger diameter recess illustrated above and rest against  the shoulder created by the smaller diameter felt seal  pocket?

Whoopee I found out how to post the pictures so mag drive reassembly should be no problem

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Bob, I'm not sure it is a thrower as the felt appears to be compressed into it's housing by the plate being pressed by the bearing when assembly is tightened up.

[Steve Jones]

Andrew, my friend, it all gets worse! Now you'll understand why I stick to coil. As I said last evening, I have no knowledge of mag engines but given the shape of the plate you refer to it may well be something that compresses the felt seal just as a similar shaped plate does to the felt in a wheel hub. If that is the case then it may well need a flat spacer if using a sealed bearing so as to maintain the status quo. Equally, that might all be a load of bo****ks!

Steve

[Ian Williams]

Besides compressing the felt the plate also acts as a spacer so although you could use a sealed bearing you will still need to make a spacer of the correct thickness to ensure the bearing is clamped in the housing. If nobody can give you the dimensions you need I will have a search through my shed I should have one in there which I can measure for you.

[Charles P]

I'll have a look tomorrow and see what's in the box for you

Charles

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PS. Don't believe Steve.
Mag engines are much nicer....

[Ruairidh Dunford]

I appears to be 1/32” thickness - open to correction however.

   

   

[Andy Cawley]

If I was to use a sealed bearing the plate would have to act as a spacer to positio the gear correctly?? How thick would a spacer be ?

[Mike Costigan]

Andy, have a word with Andy Storer or Stuart Ulph - I'm sure between them they have got the answers!

[Charles P]

If I was to use a sealed bearing the plate would have to act as a spacer to positio the gear correctly?? How thick would a spacer be ?

Andy

You could always put the gear and bearing in place without the felt or mag drive shaft, using the idler bearing to get the axial position of the mag gear correct. Then stuff a vernier in from the mag side and measure the void.
I made an aluminium spacer to replace the felt seal that holds a lip seal, running on a "refinished" surface on the mag drive shaft. Seems ok

Charles