When using 1.375" OD dom tube how is everybody threading the outside to accept the bearing/seal housing that beavertail, backwater, etc. makes? Standard 1" sch 40 pipe is 1.315" so that means the DOM is .060" larger. Will a standard schedule 40 1" pipe threader cut threads in the DOM or do you have to have them turned with a lathe?

This is the upper and lower bushing / bearing setup that I am going to use.

Just curious about that bushing and cap on the lower end that is outside the seals. What is their function?

The flange bushing is larger than the prop shaft so it doesn't provide a running surface for the shaft. I'm gonna thread the cap on over the flange bushing to sandwich the seals between the two bushings inside the shaft housing to prevent them from moving around.

I wouldn't put a bushing on the top that will just add extra heat to the bearing.

Run grease also instead of oil it will be better if you have a seal go out you won't be running totally dry.

The bushing on the top is bigger than the shaft so the shaft doesn't actually touch it. All the bushing does is give the seals a face to sit on so they don't move inside the shaft housing.

Also, if your flange bearing ever goes out, that top bushing would offer enough support to the shaft (even thought it would be loose) to get you back in.
I am not ignoring your original question about threading the DOM, I just don't know the answer.

Yeah it would be better than nothing. I think I have everything worked out except threading the outside of the DOM. Surely somebody has done it???

Also will be running grease for sure....... Just labeled the diagram wrong

I had machine shop thread mine. Used reverse threads to keep rotation of shaft from unscrewing it.

I would also do away with the bottom flange bushing and put seals in cap. Use a flanged bushing. The cap will hold it in place and want need set screw. The less length of exposed shaft is better. It is less likely to bent if you hit something. If you do it like this it will be like go devils set up.

I like the idea of putting the seals in the cap and would rather do that for sure but how do you keep the cap from crushing them when you tighten it down on the housing?

I think you would want to put the seals into the DOM, just as you show them (only at the very end of the tube) and then tighten the cap down on the back of the DOM and not on the seal itself.

Power731 is talking about only having one bushing (a flange bushing) and the face of that bushing will sit against the face of the dom housing. so then the pip cap threads down and holds the bushing into the tube. Only problem with that is then the seals have to have a spot machined into the cap for them to sit in so they dont get crushed when you tighten down the cap to lock everything together. All the machining gets expenisve. or maybe he has a different approach?? thanks for all the help guys this is really helpful.

I went with 1 3/8 x 12 threads and a threaded a cap with an od of 1.5''.

My best advise would be call BackH20 and they will send you a bearing assembly with seals and threaded adaptor. all you have to do is weld adaptor to tubing and you have bearings instead of a brass bushing. Which is a lot better.