Alignment of shaft.

Is there a trick to getting the shaft back to where it was exactly. After replacing real seal in transmission I pulled shaft back up aligning the bolts and tighten them up. It appears I might have a very slight miss alignment. Before a run it out I would like to make sure I didn’t miss anything. Thanks

The trick is to get the boat afloat and "settled" overnight before conducting and engine-to-shaft alignment. Spend the intervening time getting the engine mounts all loosened up. This is not rocket surgery, and there are plenty of youtube tutorials on the topic.

more detail please. You aligned bolts and tightened them up. What is not in alignment now.

When you pulled the shaft up the the flange did everything line up or did the bolts make it line up.

The shaft often need a good ‘lift and tuck’ after it’s been unbolted. Bring it in with the bolts . Leave .125” gap. Then start bringing it in evenly . Measure as you go. .002” would be sufficient

I tried to post a 30 secco deal but it wouldn’t upload. Said it wasn’t allowed. I will loosen up bolts and re tighten. It’s probably just me trying to be to perfect. Thanks

I tried to upload a 30 second video but it said not allowed. It might just be me trying to be to perfect. Will loosen bolts and replace tighten. Thanks

captbuddy said:

I tried to upload a 30 second video but it said not allowed. It might just be me trying to be to perfect. Will loosen bolts and replace tighten. Thanks

Click to expand...

Please do yourself a favor and remove the bolts. If the flange and shaft do not line up without the bolts then you have work to do. AS said already, is the boat in the water or on the hard.

It could be that the engine alignment was off to begin with and you just couldn’t tell before you unbolted it. Now you need to get the boat launched, let it rest for several days and then do an engine alignment. You are allowed .001” for each inch in diameter of the coupler face. So a 6” coupler should measure less than .006” all around the coupler. Tighten the bolts to bring the shaft up all the way, then loosen the bolts and do the measurements.

It does not do much good to align a shaft when the boat is on the hard.

pete

It stays in the water.

Well then, you can proceed with the process.

Yeah, it could have been stressed before the unbolt and slide back, so just proceed with the usual process.

Comodave said:

It could be that the engine alignment was off to begin with and you just couldn’t tell before you unbolted it.

Click to expand...

That's what I'm thinking. Don't assume it was properly aligned before you disconnected it.

I am a DIY guy but this may be one for the professionals.

Osprey69 said:

I am a DIY guy but this may be one for the professionals.

Click to expand...

I'm going through an alignment on my boat as we speak. I am an ok DIY mechanic my whole life, but this is something I would not have been able to do even in my prime which is long past. Thank God I have my boat at a good yard with quality workers that I trust 100%. It will be expensive, but will be done correctly. But expensive is relative. Boat dollars are like monopoly money, not real.

Osprey69 said:

I am a DIY guy but this may be one for the professionals.

Click to expand...

Well, you can always go down there and bolt it back up loose, like advised, eighth inch gap, not tight. Then do the gap measurements and see what the numbers are.

Get your eighth inch on all bolts as you rotate the shaft (by hand) at the same location and then measure all around at different points without rotating the shaft.

I should have added that when you are rotating and measuring do not adjust anything that is less than an eighth inch. Do a full turn to make sure. At the end of the process you should have an eighth inch minimum on the tightest spot and all the rest will be more.

One of the steps to a proper engine alignment commonly left out of internet descriptions that I read is the need to check the alignment of the coupler face to the shaft. This needs to be done in all four possible orientations because if the coupler is not properly faced and is out of alignment with the shaft, you will never get the vibration out of the drive-line as the shaft will not actually be in alignment even when the faces appear to be parallel in the one orientation measured. If the coupler face is out and was rotated, it might explain why it appears to be out of alignment with the engine now.

These articles might be helpful, one of which is a how-to.

Alignment two part
https://stevedmarineconsulting.com/the-ins-and-outs-of-engine-and-shaft-alignment/

Alignment how to
https://stevedmarineconsulting.com/wp-content/uploads/2021/04/TaskSheet190-EngineAlignment-05.pdf

Prop installation (since you'll need to do this too I assume) how to
https://stevedmarineconsulting.com/...08/Prop-Install-TS198-PropInstallation-02.pdf

Accounting for shaft droop or sag is one of the less well understood features of getting the alignment right. You can do a rough alignment while hauled, but a final alignment can only be completed while afloat.

In Brisbane Australia