Shaft Alignment

The latest in my transmission saga . . .

I installed a new vibration damper on the flywheel, confirmed the transmission pump position and mounted the replacement tranny. I read all the alignment threads here and the excellent write-up on yachtsurvey.com and set out to align the shaft to .003 or better.

After hours of trying yesterday, I was unable to achieve alignment. In fact, I would estimate that I didn't get much better than 0.1". What needs to happen in order for it to align is for the front of the engine to move to port. I loosened the front mounts and tried to pry it over (what do you guys pry against?). But the engine would move back to starboard as soon as I let off the pry board. Then I lifted the engine from above using the hooks and pried it towards port when there was no load on the mounts, but the front of the engine still snaps back to port when I take the pry board off.

Any ideas?

Go back to the strut and set the shaft concentric in it. Prop the shaft in position from inside and move the motor to it. I've found that it helps to get it close before the center of the 'halves' are together. That nose in the coupling can mislead.

The other thing if you're getting wierd readings might be that the shaft is bent. Try turning in 90 degree intervals. If the reading changes, the shaft isn't happy.

Shawn,
I'd like to back up Greg as he's absolutely correct above. Start with the strut and make sure it's aligned with the hull hole/log first. There's no sense in aligning a engine to a misaligned shaft/strut.

Also, backing up Paul, make sure the pinch bolts are loose. Put pressure on the one side with the pry bar and tap the other opposite mount with a hammer to see if it will move in towards the engine. They can be pretty rusted up. Some have had to remove them from the engine and loosen them up on the bench.

Sounds like the motor isn't sliding on the mount, it sounds like your moving the rubber motor mount itself and then it's returning to the original position.
Is there still room to move the motor to port or are you out of mount play.
Will it slide starboard and stay?
Do you have the rear loose at the same time as when your trying to move the front?

The first pic has 2 amateurish diagrams I just made. The top diagram shows how much room there is on the port side of each of the front engine mounts. A lot. The black circle is the vertical mount bolt.

The bottom diagram in the first picture is the mount diagram. (see second photo for rear/tranny mount type).   What I think is going on is that the tranny mount axis (in red) is not straight and is forcing the engine to the starboard side. Thoughts?





The second pic shows the mount type. The outside part (on the right, with the vertical surface) bolts to a piece of angle iron lagged into the top of the stringer. I'm thinking I could test my theory by loosening the bolts holding the mounts to the angle iron/stringer.

Thanks gun. The front will slide starboard and stay.

All of the mounts are loose. But the rear mount being able to slide side to side or up and down would not fix a crooked axis problem.

Yes, same motor. However, I loosened the front mounts so that I didn't break anything when I lifted the rear to remove the tranny. I didn't tighten the front engine mounts until after installing the replacement transmission with its mounts.

Also, I removed the rear mounts WITH the transmission, leaving only the angle iron on the stringers in the rear. The rear mounts did not want to go easily back where they had been.

I'll give your suggestion another try next time I'm out there.