strut alignment - part 2

I did a dry fit of my strut last week after getting it back from the shop. Slight cutless gap but nice, easy shaft rotation by hand, no prop installed.

I installed it yesterday and the difference between my dry fit and having it torqued down made it noticeably tighter/harder to rotate. I can see it's pinched more on one side and at the bottom of the cutless bearing.

The shop said my strut was "slightly" bent and they corrected that. So slight they didn't charge me for it. Which direction, I don't know.

I was going to sleep last night thinking, damn I should really have immediately removed the strut and shimmed it to correct the difference.

But, I didn't have the coupler disconnected from the engine so I'm thinking that an alignment should get me where I need to be. The shaft is basically centered in the shaft log, maybe a little high. I'm going to head back, disconnect the coupler and hoping that it will have a little "spring" to it, meaning my current engine position is creating the tension I feel on the shaft now.

If I'm correct, shimming the strut would have been a mistake since I didn't have the engine uncoupled. I had this "ah hah" moment last night after reading a post saying stating "the engine is always aligned to the shaft position", not the other way around.

Bob

Right. You have to rough align the coupling to the motor before the strut can be properly aligned. But only ater the boat has floated for a week or so can you final align the coupling.

Jeff

Bob:

Here's the order of alignment used by every boat builder I've ever discussed the topic with (from the $100K mass produced to the $5M one-of-a-kind)

1) get the shaft centered in the log (hull penetration point), usually needs to be shimmed/supported as there isn't a coupling on the end (on new builds)
2) Install strut over shaft and position strut to hull - Shim strut as required to center shaft in cutless bearing. Verify final shim selections and trial fit with real hardware.
3) Assembly strut to hull with bedding compound and install shaft with stuffing box hardware 'loose'.
4) Assemble shaft with coupling and then adjust engine mounts to centered shaft
5) remove shaft supports and complete 'stuffing box' assembly.

Bottom line - You need to ensure the strut-shaft-log are are assembled concentrically BEFORE moving the engine around. IF you know the engine alignment is correct (and motor mounts haven't worn, etc) are all questions that MUST be answered BEFORE you know how well your running gear is aligned.

I disconnected the coupler last night and the shaft dropped a little, now it's perfectly centered in the shaft log where before it was a little high before. It's still slightly off side/side in the bearing though and looking back at a picture from last year, it was with the old bearing too. I didn't have any vibration or play before but wanted to rebed the strut and figured it was time to replace the likely original bearing at 22 years.

So, if I realign the engine like I did last year, I'm basically in the same position but with a new cutless bearing installed. Do I go that route and deal with the strut alignment next year? I know that's probably a rhetorical question so let me think about it and get back to you guys

If I didn't JUST reinstall the strut I'd have a little more steam to deal with this now. No doubt it will be a lot better with the engine alignment, the two flanges don't line up now that they're disconnected. That would explain why the shaft got so much harder to rotate between my dry fit and final install. Thinking back on it, I didn't have the nuts near tight enough for the dry fit.

Bob

bobct said:

the two flanges don't line up now that they're disconnected. That would explain why the shaft got so much harder to rotate between my dry fit and final install.
Bob

Click to expand...

THe shaft will have some sag when the flanges are disconnected, especially when in a single strut installation. So, I would not expect alignment in the unbolted state.
Can you find any position in the boat where the prop shaft is easily turned and doesn't rub the hull or log?

Dave - with my stuffing box setup, the shaft log/hose sort of holds the shaft in position when it's disconnected. Not a huge difference (when it's aligned correctly) between uncoupled vs. coupled. The back of the engine is about an 1/8" (eyeball) too high now so the shaft was being pulled "up". Even though it's off side to side in the cutless, it's centered in the shaft log and rotates pretty easily now but it's still uncoupled and I'm not feeling the tranmission drag.

If I loosen the stuffing box hose, I can get some side to side adjustment. I have the spud style packing box so the shaft position will change depending on where the hose is positioned. There's a limit but maybe I can split the difference side to side on the shaft/cutless position this way. I think that's why the call these "self aligning".


http://www.buckalgonquin.com/pages/ProductPages/drivetrain/PB_standard_spud_page.html


Bob

The Self-aligning is just the box to the shaft - nothing with shaft-hull, shaft - strut, or shaft - engine.

If you have replaced the cutlass bearing and do not align the shaft Bob, you will have premature wear in the cutlass... depending on use and after all of this I am sure you are going to use the boat