Shaft strut movement

With the strut moving like it is, I highly recommend checking the alignment. Then, bed the complete strut base is 4200 (or equal) as it will bond the strut to the hull.

Apologies if this is a stupid question, but is there any way to bed the strut without pulling the shaft out? Or is it impossible to align the strut with the shaft log with the shaft inside both? I want to avoid the coupling removal and reinstall process if possible...

8122pbrainard wrote: Leave the shaft in. You will use it to align the strut to the log. Have you watched the alignment video? There's a link in the FAQ thread in the maintenance section. How's the cutlass bearing?

I have watched the alignment video, yes - very helpful, thanks.

Cutlass bearing looks fine to me? See below. Doesn't have many hours of use on it - I've had so many dramas with my boat it has spent more time in workshops than in the water.

Thru-hull intakes feeding four Jabsco pumps that fill four ballast tanks I've had installed in the boat for wakeboarding.

Other than Pete's alignment video, this appears to me the most comprehensive discussion of the strut alignment and bedding process? Or are there other threads that will also be helpful?

Thanks again for all the advice and guidance!

So I went through the re-bedding process with as much care as I could. I needed a lot of shimming (four washers at the back), so built a new base for the strut with epoxy putty as per the recommendations here, here and here. Despite doing my utmost to align the shaft with the center of the log, when the bedding process was complete and everything dry and tightened, the shaft naturally sits slightly to starboard of center in the log. Not touching the side, but definitely off center. This is also where it was sitting before I removed the strut to re-bed, and because I'm using the same bolt holes to fix the strut to the hull, I suspect the alignment of the bolt holes and how the bolts tighten down in the holes pull the shaft slightly to starboard when tightened. I did my utmost to keep the shaft centered as the strut was pulled tight against the hull after applying adhesive, but seems this wasn't as successful as I hoped it would be.

Be that as it may, I proceeded to align the engine with the shaft. I could not get the engine moved far enough to starboard to align perfectly with the shaft in its natural 'happy place' position - it was off ever so slightly as per the picture below.



However, I pressed (not bolted) the two flanges together and managed to get them within 0.003" parallel all around while pressed together. After bolting them together properly, I can spin the shaft quite easily with one hand, but I did notice a bit of tightness during some part of the shaft's rotation after tightening the coupling bolts down all the way. The tightness only emerges when the bolts are fully tight - anything looser than that (even just a fraction) and there is no tightness at all.

I proceeded to separate the coupling flanges and tried to pry the engine to starboard some more, as I suspected the slight lateral misalignment is causing the bit of tightness in the rotation (I did measure the shaft for straightness with a dial indicator prior to this whole process). No luck. The rear starboard motor mount looks like it has a bit of room left to move the motor to starboard (judging by the marks on the pin - circled in orange in the picture - it looks like the pin has been deeper into the engine mount in the past than what I am able to get it), but try as I might I cannot get the engine to move that last fraction of an inch to starboard.



So my questions now are:

1. Is a bit of tightness in the shaft rotation acceptable at all? If I can spin the shaft with one hand, and rotate the prop with one finger, is that an acceptable level of tightness?

2. If not, any advice as to how to potentially move the motor that last fraction of an inch to starboard?

3. Or should I go through the strut bedding process again and get it better aligned with the shaft log/engine - potentially modifying/covering up existing bolt holes and/or drilling new bolt holes for the strut bolts?

Thanks for any help and guidance here!

I did not specifically measure the strut when it was off, but I did not notice any signs of it being bent.

Measured the strut base to chines, and if anything the strut is mounted a bit to the port side of the center of the hull. Which does suggest that the bolt holes aren't perfectly aligned with the shaft log, hence it sitting a bit to starboard.

Be that as it may, I went through another round of engine alignment. Still couldn't get the coupler flanges perfectly aligned horizontally when they're not pressed together, but it seems I did a better job this time around, as essentially all tightness/binding through the shaft's rotation is now gone. Perhaps my alignment just wasn't as good as I thought it was the first time round.

SNobsessed wrote: If the coupler halves are not visibly aligned when loose, it seems unlikely they would pass the .003 inch parallelism test when coupled. Are you lifting the shaft a bit to check? The feeler check is done before tightening the bolts. Sorry for the info if you are already aware of this.

This post seems to reinforce the notion in the first that you can force the shafts together and perform an “alignment” from there. On the contrary, if you aren’t aligning the powertrain to where the shaft spins freely in the strut, it doesn’t matter how parallel you can force the faces to be- all you’re doing is dialing in a massive misalignment.

If you can’t get the engine to line up with the shaft when spinning freely, then time to look at the strut again. The pcm mounts have a lot of adjustment in every direction ... if you run out of adjustment then something is WAY off. I suggest a dry fit and mock (gross) alignment check before bedding the strut on a new/re install. Some have been known to bend the strut while installed on the boat, but I suspect Pete would frown upon that.

TRBenj wrote: If you can’t get the engine to line up with the shaft when spinning freely, then time to look at the strut again.

Post my second round of alignment, the shaft is now spinning much more freely around its full rotation, so I think I'm there. As noted, I can easily spin the shaft with one hand at the coupler. I have yet to fit the prop again (want to do a proper lapping), but in the past (i.e. before I reinstalled the strut, and when I suspect alignment was worse than it currently is) I could rotate the prop with one finger, despite this not being equally effortless around the full rotation.

TRBenj wrote: I suggest a dry fit and mock (gross) alignment check before bedding the strut on a new/re install.

I did this, and thought I had it spot on, but it seems that in the final installation process - specifically when tightening the strut mounting bolts down fully - the shaft gets pulled slightly to starboard (with reference to the center of the log). It was in exactly this position before I removed the strut for the re-bedding process, hence my suspicion that the bolt holes are drilled (or have worn out) in such a way that when the bolts are fully tightened there is this tiny bit of residual misalignment with the log.

Thanks for the advice and guidance!

Im sorry for the long wind and dont want to hijack or make enemies.

This is on my mind as well, as im maybe a month or so away from reinstalling the drive line.
I know im going to have to rebed the log just by looking at how the strut was shimmed and mounted, and how the engine mounts are thrown over to port. I just dont want to admit and commit yet.

I seen a video where they figured the weight (including coupling) that needed to be held up so the shaft was straight before they begin alignment. Something about length, weight of coupler, weight and span of the shaft.
They used a chainfall with a scale on it to keep the shaft from sagging at the coupler end, when the scale read the calculated amount then true and accurate alignment was achieved.

If i read and understood a previous post that is what the member is saying ( pick up the coupling end of the shaft, its sagging)

TRBenj wrote: The point being you can’t just force the shaft over to where the powertrain is and expect face parallelism to save you.

Point taken. Little weekend project coming up for me...

SNobsessed wrote: Double also - If you remove strut, you can check for true by putting in on a big pc of paper on flat surface, like kitchen counter. Mark the mounting holes, then project down the centers of the bore ends. You will need a big square & some pipe or wood dowel. I bet you will find it twisted.

Bingo. Strut is indeed ever so slightly twisted. Best way to straighten it out? I don't have an old drive shaft that I can use as a lever, and don't want to pull the one from the boat just for this job, so any other advice perhaps?

This is what I did, but I think it is easier just to buy a new strut.

They are not easy to bend!

Straightening strut

Most guys are using a threaded rod, nuts, & the right sized washers. A socket would be helpful too,.

Wilhelm Hertzog wrote: Okay to wrap up: I had the strut's mounting bolt holes drilled slightly bigger, and then went through the bedding/bonding process again. The slightly larger holes gave me enough play to get everything lined up right this time round. No tightness anywhere in the rotation anymore. Fitted new Vesconite Hilube cutlass bearings while the strut was off and lapped the prop to the shaft, so hopefully the drivetrain won't have to be pulled apart again for some time now!