Prop Shaft Alignment Yearly Maintenance Item

[cab13367]

Nevermind Al. Took a look inside the engine compartment just now, and saw what pins you were talking about. Done and done.

Sorry that was unclear. For the benefit of others, the "bolts" that the nuts are threaded on are not really bolts, those are the pins. So just back the nuts off almost all the way to the end then gently tap the threaded end of the pins towards the rear of the boat and they will pop loose.

[squeeg333]

So I've got an additional question for you guys regarding this. I was able to move the engine around to attempt to get the engine aligned, got it pretty close but was seeing some strange numbers. So did a little more looking and found out that when the shaft is fully uncoupled from the v-drive, and the shaft coupling pulled away from the v-drive coupling a little ways (to get the prop shaft coupling off of the shoulder fit on the v-drive coupling), that the prop shaft isn't sitting in it's "natural" position.

The prop shaft, with no pressure of alignment with the bolts, or the fit of the couplings, is offset to the starboard by about 3/8". So, when coupling the shaft together, the shaft actually has to be pulled to the Port side by that amount to mate up the couplings. So, I'm at an impass.

I think what I am going to do is butt the couplings together as they are both in their natural position, and check the alignment that way. If both starboard and port sides are the same, it tells me (I think) that I have to more the whole engine to the starboard. However, and I hope this is the case, that they aren't aligned, and I need to move either the front or back of the engine to clear up the majority of this. The reason I say that is because I have a very small amount of room that I can move the back of the engine to the starboard (the muffler is just about to hit the starboard v-drive divider). So I hope I only need to move the front of the engine to clear up this gap.

What do you guys think. Does this make sense. If I would have thought about it, I would have taken a photo of the coupling.

Any other options you guys can think of?? Like I said, I've only got a small amount of room to move the back of the engine to the starboard, so I don't have much fudge room for the back...

Help!!

[rdlangston13]

is your strut bent?

[kaneboats]

So I've got an additional question for you guys regarding this. I was able to move the engine around to attempt to get the engine aligned, got it pretty close but was seeing some strange numbers. So did a little more looking and found out that when the shaft is fully uncoupled from the v-drive, and the shaft coupling pulled away from the v-drive coupling a little ways (to get the prop shaft coupling off of the shoulder fit on the v-drive coupling), that the prop shaft isn't sitting in it's "natural" position.

This is my issue with the whole process. What keeps the prop shaft from adjusting to its own "natural" position or sitting in its own natural spot or moving from there when it's uncoupled? How do you account for this?

[rdlangston13]

This is my issue with the whole process. What keeps the prop shaft from adjusting to its own "natural" position or sitting in its own natural spot or moving from there when it's uncoupled? How do you account for this?

i think that the idea is since the shaft is center in the strut as well as in the packing at the thru hull then it should be held straight where it is supposed to be. if there is a large variance then it could be that something is bent?

[cab13367]

So I've got an additional question for you guys regarding this. I was able to move the engine around to attempt to get the engine aligned, got it pretty close but was seeing some strange numbers. So did a little more looking and found out that when the shaft is fully uncoupled from the v-drive, and the shaft coupling pulled away from the v-drive coupling a little ways (to get the prop shaft coupling off of the shoulder fit on the v-drive coupling), that the prop shaft isn't sitting in it's "natural" position.

The prop shaft, with no pressure of alignment with the bolts, or the fit of the couplings, is offset to the starboard by about 3/8". So, when coupling the shaft together, the shaft actually has to be pulled to the Port side by that amount to mate up the couplings. So, I'm at an impass.

I think what I am going to do is butt the couplings together as they are both in their natural position, and check the alignment that way. If both starboard and port sides are the same, it tells me (I think) that I have to more the whole engine to the starboard. However, and I hope this is the case, that they aren't aligned, and I need to move either the front or back of the engine to clear up the majority of this. The reason I say that is because I have a very small amount of room that I can move the back of the engine to the starboard (the muffler is just about to hit the starboard v-drive divider). So I hope I only need to move the front of the engine to clear up this gap.

What do you guys think. Does this make sense. If I would have thought about it, I would have taken a photo of the coupling.

Any other options you guys can think of?? Like I said, I've only got a small amount of room to move the back of the engine to the starboard, so I don't have much fudge room for the back...

Help!!

First thing I would do is remove all the coupler bolts then have someone slowly spin the prop and see if the prop shaft coupling moves around or spins true. If it moves around, then you have a bent prop shaft. If it spins true, then move the front of the engine to starboard to line up the v-drive coupling with the the prop shaft coupling. Once it's lined up, I would lock down ONE of the front pins so that when you slide the back of the engine to even out the gap, the engine is rotating about one fixed point. This is what I did when I slid the rear of the engine to starboard - I loosened one of the front pins and locked down the other so that the front of the engine would not also slide.

On mine, the couplers stayed perfectly lined up even with the bolts loose (I didn't remove the bolts, just loosened them) and I was moving the rear of the engine which led me to believe that that couplers mate with each other somehow, keeping them always aligned.

Let us know how it goes.

Al

[cab13367]

This is my issue with the whole process. What keeps the prop shaft from adjusting to its own "natural" position or sitting in its own natural spot or moving from there when it's uncoupled? How do you account for this?

Kane,

I wondered about this too since the couplers on mine stayed perfectly lined up. I think that they must mate up somehow to keep aligned. I did not remove the coupler bolts, just loosened them, so maybe that is what kept them in alignment.

Also, after I got the gap to within .002" on one side of the coupler and zero gap on the other side, I loosened the rear pins and one of the front pins to try and get the gap perfectly even. After doing that, I suddenly had gaps of .016" to .019" at different points around the coupler. What happened is when I loosened the pins, the whole engine must have slid forward a tad creating the large gaps. So I just moved the engine to starboard to even out the gaps so that it didn't vary more than .002" from any two points on the coupler. I then tightened all the trunnion pins and checked the gap again before tightening the coupler bolts and they were all betwen .004" and .007". I got tired of messing with it at the point and tightened all the coupler bolts and torqued them to spec.

I will keep an eye out on the shaft packing nut (I changed the packing rope again while I was in there) and see if starts leaking water in a steady stream, I may have to go in and close the gap a little tighter.

Al

[kaneboats]

Excellent. That makes pretty good sense. I'm assuming, since I had a shaft and strut replacement at the very end of last season that it's all OK for now. I'll check it when I do my mid-season checkup and post up any adjustments I make.

[squeeg333]

Well, I'm happy to report that I was successful in getting the engine and prop shaft coupling aligned. With phone call help from Doug (Docdrs), and some advice from Al, I was able to tackle this.

As I mentioned previously, when the coupling bolts were removed, and the two couplings were pulled away from each other so that the fit on the v-drive coupling was not engaged to the prop shaft coupling, the propeller shaft would naturally sit about 1/8" to the Starboard of the v-drive coupling. Sitting in this orientation, when mated up, the prop shaft was constantly being pulled to the port side. You can see in the first two photos below the offset of the two couplings.

So, to align the couplings I had to move the front of the engine. I loosened the front two trunnions by releasing the two trunnion pins. Then, using a crow bar, I was able to move the engine to the starboard until I was able to get them to line up. To check that, I repeatedly would check how the fit on the v-drive coupling affected the prop shaft when the two coupling were brought together. As you can see from the third photo, I had to move the engine about 1/4". Marking the trunnions prior to moving the engine was important, so you know where you started, and how far you've gone. The last two photos show how the coupling mates up now, just like it should. The photos have a bolt in them, but that bolt slips in very easily, meaning the couplings are concentric, and the prop shaft, when coupled with the v-drive, is still in it's 'natural' position.

Once I got the two coupling concentric, the next task was an engine alignment. This involved a lot of minor tweaking of both the front and back trunions, and more up and down movements than the side to side.

When raising or lowering the front of the engine, be sure to make a mark on a flat of the nut you will be turning and the top of the trunnion, so you know how many revolutions, or 'flats', you have turned the nut. Also, when raising or lowering the back of the engine, be sure to make identification marks so you know how many turns you've made, and to help you make smaller incremental changes (I marked the threads and the flat part of the trunnion in several locations).

I was able to get everything aligned to within .002 or less. It took me several hours to do all of this, as I was doing this by myself, but this is MUCH better than it was, and I am very pleased that the couplings are aligned, and everything is in it's natural state. The propeller turns much easier now as well.

Thanks again for all of the advise I got. This was kind of fun - though my knees weren't happy with me for about a day.

[viking]

Are you guys doing this on the trailer or on the water?
Does it matter?