repairing old outboard lower unit...plain bearing as thrust bearing?

pontoonvolts said:

Hi all. Bear with me, as I'm not an engineer or machinist by trade.

I'm repairing an old (circa 1970's) electric outboard lower unit, specifically replacing the miter gears. The interesting thing is that it contains no needle/ball bearings...it's all plain bearings or bushings. That includes what i'll call the thrust bearing; it is a block of bronze supporting the prop shaft at the front (distal to the prop) and it appears the face of the miter gear on the prop shaft transmits thrust directly to that bronze block (which is a loose press fit into the lower unit itself). Everything runs in a bath of 5W30 oil for lubrication.

Now my issue is that i'll need to shim the miter gear on the prop shaft so that it has the appropriate mounting distance from its mate coming down from the power head, and am at a quandary about what shim material to use. I'm thinking just a normal carbon steel shim would work, but was wondering if it makes more sense to use a softer material (brass? bronze?)to limit wear on the thrust block....

The newer versions of this actually incorporated a needle bearing on each side of the prop shaft miter gear (which makes a lot more sense) but retrofitting that would be beyond my capacities at the moment.

Thanks!

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digger doug said:

What machine tools do you have at your disposal and skills ?

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crossthread said:

This does not answer your question specifically but may help a little. I think if I was building that motor today, I would still prefer bushings and "plain" bearings. If a little water gets into that lower unit, I would much prefer the bushings to needle bearings. Bushings are much more forgiving then needle bearings.

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