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Magneto Fibre Gear Lucas MO1

Good morning all.

Sorry for a lengthy post.

I’m in the process of reassembling my magneto having fitted a fresh armature, slip ring and drive end bearing.
The end float is correct (after it becoming wildly different with the replacement bearing) and I’m now getting a nice healthy spark.

Reference the fibre gear, it appears to fit both ways (sort of) but the deeper side towards the mag makes more sense bringing the outer face of the gear flush with the dynamo drive gear. The problem is, in this position, the back side of the gear lightly brushes the mag body as it revolves.
It fits the other way too and although it’s about 1/8” proud of the mag housing and dynamo gear, it’s still contained within the cover plate when fitted.
Which way is correct please?

The other slight issue is that the nut which holds the clutch in place and pokes through the hole in the cover, The hexagon brushes the inside of the cover slightly (same with the gear fitted either way).
The cover was slightly deformed which I’ve corrected, now I don’t have any rubbing, but only by a few thou.

For some background to what I’ve done-
New armature
New slip ring
New drive end bearing
The above resulted in the slip ring being off centre (towards the drive end) in relationship to the pick up. I corrected this with removing all shims from between the slip ring and armature and making a 0.030” shim to fit under the drive end bearing.

Last but not least, I’ve read on some previous posts (I took the time to search this time 😀) that the fibre gear should be lightly greased, I’m not clear about the clutch though. It wouldn’t make sense to grease that too, or would it??

As always, any help appreciated.

Stay safe,


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Re: Magneto Fibre Gear Lucas MO1


Armature Drive disk should sit almost flush with fiber gear, with the deeper recess of the fiber gear facing the large hex nut retaining the steel pressure ring and Star spring. Hex nut should not contact cover when assembled. There may be some slight issues with bearing spacing on the armature which is shifting the armature position. The outer gear case covers can become a bit distorted from decades of use and abuse as well.

A bit of grease on the fiber gear teeth is all that is required.

Hope this is useful...

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Re: Magneto Fibre Gear Lucas MO1

Part number 463.112 is very prone to distortion...I have had some made from a thicker material to cure the problem...This also helps the spring 463.114 if it isn't a new one, adding a little pre load to compensate for any 'settling' of the spring..
Contact me off forum if you want one...Ian

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Re: Magneto Fibre Gear Lucas MO1

Thanks Gents,

Ian, I’ve sent an email to you.

Thanks again , G.

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