Prop Fastening

[sjaltobelli]

I recently replaced my the lower unit on my 1990 90hp force with a lower unit from a 1986 125hp force. I am trying to install a prop on the 1986 lower unit. It appears that the nylock nut is 5/8" fine thread. I am having difficulty finding the 5/8" fine thread nylock nut and a bent tab washer for my prop shaft. I have a castle nut that fits my prop shaft. The 1990 lower unit appears to have a larger nut (possibly 3/4"). I was able to find this larger size at the marina, but cannot find the smaller size anywhere. Does anyone know where I can find this?? Thanks.

 

[Frank Acampora]

Re: Prop Fastening

15/16 nut. You may be able to find a steel one in auto stores for a temporary. But for stainless or bronze, you will need to try something like Fastenal or perhaps Tractor Supply, graingers ot McMaster-Carr, etc. I'm sure the Mercury dealer will be happy to sell you one for 15 bucks!

In a pinch, If you have the power tilt with the 5/8 rod passing through the bottom of the engine clamps, that nut is the same thread and will fit. The rod is usually corroded tight and will not move even with the nut off.

 

[sjaltobelli]

Re: Prop Fastening

Looks like I found one at McMaster. Any ideas on the bent tab washer?

 

[tjello327]

Re: Prop Fastening

They are calld bearing lock nut washers. I use them at work & I buy them from Motion Industries. McMaster Carr may have them along with MSC/J&L industrial (mscdirect.com). I ended up making a custom stainless steel washer for mine. It would allow me to tighten the nut while the plastic flange was being drawn up tight, at this time the washer (which is a step washer) would hit the spline diameter and draw up solid to this face. Everything now is super tight and will not back off. You will need to know someone who can turn one on a lathe and take proper measurments so the plastic flange dont crush before the washer draws up on the spline face.