prop shaft clearance at engine end

[c.K.]

hi
recently I replaced shaft cutlass bearing and prop
The walls of the shaft tube at the engine end were very thin so I decided to burn all the rubber out of the old cutlass bearing cleaned it up and epoxied it into the very worn shaft tube it did not leave me very much clearance and i can move the shaft freely only a few mm in all direction
the coupling is a directly bolted to the gear box should I consider a flex coupling in betewwn or is the present ok

[tkeithlu]

Hold on a moment.

OK. The position of the prop shaft can be centered in the shft log/tube, right? The question then is aligning the engine to that shaft without moving it. Do that by adjusting the engine mounts until the two flanges are as near concentric as you can see/feel.

Now. Is what I just said condescending and trivial, or is this a new process for you? Do you need help with how to do the alignment?

Soft couplings are grest for taking up misalignments so small that you cannot measure them. They are not a substitute for doing the alignment. If you'v got space, yeah, get one.

[Tetepare]

I’m confused. Is the shaft tube the log? How does that equate to “engine end”? Burned out what rubber, the cutlass bearing or (hopefully not) something else?

[tkeithlu]

Shaft log is the tube the prop shaft goes through, with one or more Cutless bearings inserted therein. Most have just one bearing at the prop end; mine has one at the transmission end as well. As I understand it, C.K. salvaged a Cutless bearing and used it's bronze tube to reinforce the upper (engine, tranny) end of the tube. That left very little space around the prop shaft where it goes through the bronze tube. His/her task is now to align the engine to the shaft.

[team karst]

The "centering" that is required is to insure the cutlass bearing is not compressed at either end because the shaft is not centered. Centering on the stern tube is not a consideration, only that it not touch.
Also, if the shaft is "hanging", without the engine side connection, it would NOT be centered in the cutlass. It needs a correct engine side flange position for support.

Further, the shaft could be centered just fine, but the coupling flanges are not parallel, causing shaft bending during rotation. So, its a bit of a geometry problem to solve, that is usually solved with correct engine mounting and feeler gauges.

[c.K.]

Originally Posted by tkeithlu

Hold on a moment.

OK. The position of the prop shaft can be centered in the shft log/tube, right? The question then is aligning the engine to that shaft without moving it. Do that by adjusting the engine mounts until the two flanges are as near concentric as you can see/feel.

Now. Is what I just said condescending and trivial, or is this a new process for you? Do you need help with how to do the alignment?

Soft couplings are grest for taking up misalignments so small that you cannot measure them. They are not a substitute for doing the alignment. If you'v got space, yeah, get one.

Many thanks for that I did line up the engine and used feeler gauges to check so i should be fine
think I'm going to test run without fully tightening the mounts to the stringers just to let it settle a bit