Lateral Adjustment for Shaft Alignment

Someday I will stop bothering everyone with questions, today is not that day.

I am in the process of aligning the transmission coupling and the drive shaft coupling. I had to install 1/2" shims under the front engine mounts in order to raise the engine enough to meet the coupling.

I have watched the alignment video and it provides a great tutorial. It isn't clear to me how the engine/trans side of the coupling is adjusted laterally. I attached a few pictures of the rear mount and the coupling mating approach. I need to get the engine side to slide about 3/8".

Any advice is appreciated.

By "exhaust hose", Chris meant "raw water pickup hose".

I did the same strut replacement on our BFN (original 6A to replacement 6A6) and noted some significant casting differences as well. We chose to alter the base of the strut in order to get it aligned with the log properly... took nearly 1/16" off the forward mating surface (down to about nothing in the rear). How does yours line up with the log when the shaft spins freely? Thats the most important thing to check before proceeding with the forward half of the alignment (so dont skip this step!). The packing gland and log hose should be removed for this.

Those 2 methods of increasing clearance to get the socket onto the ARE will both work... doing both might make your life easier. I assume you were planning to replace the packing anyways while you had it all apart?

No, that log hose can be cut down a good bit... so long as the packing gland and log dont bottom out on each other, youre good to go.

Detach the couplings and align the powertrain to where the shaft spins free. Otherwise, you would have no idea which way everything needed to move. Three thousands (.003") is the maximum difference you can have between any 2 places on the coupler faces and still be within spec.

You may want to watch Pete's alignment video.

When youre done and are reattaching the couplers, you should be able to spin the shaft with your hand pretty easily. The prop should move with one finger. If either of the above is untrue, then youre likely still bound up and misaligned.

I think I underestimated the tediousness of the process. I will have to spend more time lining it up first. Thanks for the tips.

Thanks for the alignment tips. I have one more question.

I was able to shim the front motor mounts to them where I needed. Unfortunately, the rear motor mounts are about 1/8" too short. I made some steel shims to put between the mount and the stringer and removed the three lag screws on the top. I was unable to find any other bolts holding the mounts in place after thorough examination. When I placed the jack under and tried to raise it, the mount wouldn't budge. I am worried about putting too much stress on the fiberglass as the boat is no spring chicken. I also decided against putting jack under the rear coupling as I imagine it is pretty sensitive.

Does anyone have any helpful tips to raising the rear of the engine?

Good idea. I'll give the come along a shot in the morning.

gR@HaM wrote: An old thread I know but would be interested to get the answer on this, I too have the beginnings of a dirty neutral and the trans is difficult to turn

Graham,
Unfortunately the only cure for a dirty neutral is a trans rebuild. What is happening is the clutch plates are warped and dragging.

Thanks, understood. Although what I'm really wondering is whether the occasional dirty neutral explains the stiffness in turning the trans output coupler or there could be more to it.
Is your prop more difficult to turn once attached to the trans?

IMHO- the strut should be mounted right to the hull. Vibration will be significantly reduced.

How are you basing "hard to turn on its own"? By hand, on the output coupler? That only has a 4-5" diameter, so a 2-2.5" moment arm. At the prop, you have a 6.5" moment arm.

I have several trannies with dirty neutral and when properly aligned, I can spin the prop with one finger.

The dirty neutral should not affect your prop alignment check.
Leave all 4 bolts out of the coupler, clean both mating surfaces very well. Coat the mating surface with a very thin film of grease.
The coupler will mate up and center with the trans when properly aligned and spin freely in the coupler. The Trans does not need to turn while you align it. Just spin the shaft but be careful to not let it slip to the rear as you spin the shaft. I do not understand the reason for adding shims. All 4 engine mounts can slide in and out and up and down unless they are stuck in current position. If stuck, start spraying them with penetrating oil. You might even add heat to help pull the oil into the adjustment slides. Tapping on the slides may help get the moving. If it does not spin freely your alignment is still off. Does this tranny have good oil in it?
I was able to easily get my new shaft within .0015 at the coupler last month. I never added the bolts in the tranny connection till the coupler was in perfect alignment. Thanks to many tips on here.
I used the idea for a wood block with a v notch, it was necessary to eliminate shaft sag while working on alignment. I set the wood so the shaft was in the log center and spun free in the sweet spot. Then aligned the engine to it. Easy 1 finger spin of the prop now.