Prop Shaft Alignment Yearly Maintenance Item

I started this process. Was worried about not being able to get it done before leaving on vacation so I'm gonna put it off till I get back. I was working on doing fluid changes and such and noticed this forum so thought I would look at this. Well when I looked at the bolts holding the two shafts together they were loose and you could spin them by hand. I know someone else on here had the same problem and replaced the bolts. I took a picture of the bolts so everyone could see. The lock nuts could be spun off by hand so they weren't working that well anymore either. The threads on the bolts were pretty much shot from being loose. Also, my bolts were 2 1/4" long for anyone that wants to know if they replace them.

Found the exact same issue when I first went to do an engine alignment. Those flat threads are the ones inside the coupling, and don't come into contact with the locknuts, but it is good practice to replace a bolt showing any signs of damage. I replaced both the bolts and locknuts with new this year, and am glad I did. Just good piece of mind. I check them for tightness once in a while, just to make sure they don't vibrate loose.

One piece of advice I'd give when putting new bolts and nuts in is use some anti-sieze on the threads, or some other form of thread lubricant. As they are stainless bolts and nuts (assuming that's what you replace them with), they can gall. And once Stainless galls, it's game over. I had to cut one of the bolts out of my boat. Not fun.

Yeah I put Some on the bolts so they wouldn't seize up. I was worried that the flats in the threads was from where the bolts were loose. Also since the lock nuts were shot I went ahead and replaced it all. Now just actually need to do the alignment part.

FYI: If anyone decides to do a shaft replacement you can order a replacement drive shaft from Elbert's. It works great. It also makes future changes much easier because of the A.R.E. system. However, you should know the coupler is slightly different than the stock one and requires shorter bolts. All the info you need can be found on his site:

http://www.elberts.com/system.htm

Im a little lost. I loosened all 4 bolts and took measurements at 3,6,9, & 12 o'clock all while trying to hold the couplers together. My gap was uniformly way bigger than .005 at all points. In fact it was big enough to fit the biggest feeler through. Should I be checking the gap with the bolts tightened to get more accurate numbers? Im supposed to be running the feeler gauage through the gap between couplers correct?

I am having the same issue. I can't close the gap. Does it just need to be a .002 difference or less at the reference points (could be .012 and .014)?

I'm having the same problem as the two guys above me. What's the solution for this?

Maybe Doc can give us a new tutorial on how to check this?????

1. Loosen the 4 9/16 bolts a few turns so you can free the driveshaft output flange from the prop shaft flange.......if the two flanges are stuck together just bump the engine over

2. Now pull the prop shaft flange into the vdrive out put flange with your left hand check the gap at 12 then at 6 then at 3 o'clock . To do 9 you will have pull with left and measure with right. Yes it may require a contortion move. If you are not aligned one of these will be 0 and the others will be open. If all are open then go have a bowl of wheaties or grow a pair and pull harder on the prop shaft.


When the bolts are tight there will be no gap between the coupler plates even when misaligned . When you loosen the bolts sometimes there is no gap until you free the two halves. If you are getting open points all around the coupler then you are not bringing the prop shaft half close enough to the vdrive half.

Hope this helps, let me know

I loosened all 4 which made a gap. You're saying the two flanges should be able to completely separate? This was not happening for me. If I applied pressure with my left and measured with my right there was no changes. So it sounds like they are stuck together? I had a big gap all the way around even when applying pressure.

Quote:

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Originally Posted by yotaismygame

I loosened all 4 which made a gap. You're saying the two flanges should be able to completely separate? This was not happening for me. If I applied pressure with my left and measured with my right there was no changes. So it sounds like they are stuck together? I had a big gap all the way around even when applying pressure.

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Spin the shaft from the prop end to free the coupler.

I also found the trick to closing the gap was to push the shaft in from the prop side. I could get it close on the coupler side but was able to close the gap by forcing the shaft toward the v-drive from the prop.

With the nuts loose you should be able to move the prop shaft and coupler front to back the amount that you loosen the nuts. Sometimes the two couplers can be stuck and a slight bump of the engine over will free them if your boat is in the water or as mentioned above holding the prop and turning or and push pulling to free the couplers if out of the water. Sounds like your not measuring between the couplers if you have a gap when the bolts are tight

Bringing this one back from the dead. I decided I needed to check this so I found the four bolts and every one was slightly loose, meaning i could spin each bolt/nut. being a little concerned, I removed each bolt and didn't see any damage to them and the coupler was staying tight (couldn't fit a .0015" between them). Almost called it good to put it back together but then thought "what the hell, lets see if it is tight all the way around". So i stuck one of the bolts in the prop coupler and used it as a handle to rotate just the prop shaft. Next thing i know, the gap is probably .100". My guess is this was never checked before and a little bit of rust had developed and stuck the two together. As i understand it, the couplers are completely flat on the faces that touch and all of the force from the engine is transferred through the bolts.

I do have two questions, first is the theory behind this that the prop shaft is set where it is and the engine is what needs to move so as to not induce any stresses on the natural position of the prop shaft? second, should i be able to move the prop shaft up and down (perpendicular to the shaft) or should it be pretty locked in? i'm talking 1/4" of movement up and down.

EDIT: just re read the instructions and now i understand why it says "Holding the two flanges together". lets try this again...

Well I tried to pull the two flanges together and couldn't do it, so i put a bolt back in and was able to pull the flanges together with that. I think i'm missing something. Anyone have any ideas?

Thanks

maybe try a second set of hands pushing the shaft from the prop to get the flanges together while another measures?

Wet the strut bushings and turn the prop so the shaft is lubricated in the strut, then you should be able to pull the flanges together

Any tips on how to get a torque wrench on the prop shaft bolts? Trying to snug them up to 25-30 lbs, but I can't get a deep set socket on there while still holding another wrench on the nut.... am I missing something? Or has anyone else had an issue with this?

I could only get open end wrenches on mine if I recall correctly. They have nylock nuts so I just tighten them and check them regularly.

Thanks Kane - I like that better than the frustration of trying to get the big a$$ torque wrench in there.

Same here. No room for the torque wrench. Just used open end wrenches.

Thanks docdrs, wetting the strut did the trick. Wiggled the shaft up and checked it while turning the prop, and could never fit a .0025 gauge in. Surprised it was that tight everywhere while turning it but I'm not gonna complain.


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After having some vibrations and noticing the prop shaft coupling bolts were loose, I decided it was time to check the alignment.

The feeler gauge keeps telling me the coupling is tight at the 12 o'clock position, bolts are still in but very loose. I started lowering the front of the engine, turned both bolts about 6 times each and couldn't really tell a difference. By 6 turns I was beginning to bottom out on the mount, so I stopped.

My next move was to start raising the engine from the rear but discovered I didn't have the right size wrench for the rear jam nuts. Tomorrow I will be picking up some bigger wrenches and trying again. It also looked like the rear mounts were being stressed from lowering the front so much. Should I loosen the bolts holding the trunnion pins so they can rotate?

6 turns seems like a lot of adjustment (about an inch vertical?), does this sound right? Should I completely remove the 4 bolts from the prop shaft coupling to check where the 'natural' position is?

Oh, and for others wondering, you need a 15/16 wrench for the front mounts.
Any idea what size i need for the rear?

Today I moved the engine up and down again with the prop shaft completely disconnected and saw how quickly it comes out of alignment. I still couldn't produce a gap at the 12 o'clock position at all, the gap at the bottom remained at about .013-.014. The prop shaft does not appear to be bent since the gap and lack thereof remained in the same locations as I rotated the shaft.

I ended up putting it all back where I started and bolting it back together.

Any tips for my next try?

you have to make sure your engine rubber mounts have not deformed as well . As long as you can rotate the shaft 180 and get the same gap then you need to keep going. You need to have the bolts in loose to get a true alignment , just keep pulling the flanges together to measure. The major thing here is to be able to visualize in your head what you are trying to accomplish.

Got mine done today. Had to raise the front about 7/8ths of a turn and got it to ,0025" or so all around. My first shot at it and I was working in the hot sun so I wasn't especially nitpicky. Will dial it in more next season.

Thanks for the great writeup!

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Hi, i am about to adjust my drive shaft alignment after replacing it. Great post on how to do it, THANKS
Jim

About to do mine, Excellent post

I'm planning to do this in the spring. I've read through all the posts and have a general idea of what needs to be done.

I searched for some videos on "Moomba / V drive shaft alignment" but most of what I found was for larger boats. Has anyone on this forum seen a video doing step by step on a Moomba?

Hayden, if you find a video for a V-drive prop shaft alignment, please post the link here because I can’t see any of the pictures in the earlier posts. I completely removed the coupling bolts from the flanges and I don’t have any space between the couplings at any point. And to make sure the two couplings weren’t rusted together, I turned the prop shaft which turned the prop shaft coupling while the V-drive coupling remained stationary. Still no gap anywhere between them. So either mine is perfect or I still don’t understand what I am checking, even after reading this post twice and reading one of the links in one of the replies. I have a 2016 Moomba Craz. Thanks! Scotts

If the cutlass bearing is dry it can prevent aft movement of the shaft flange. wet the bearing and turn the prop and pull it back n forward a bit to free it. But just a 1/4 inch is all you need

I performed this alignment this weekend. It didn't go as smoothly for me as it should have. The whole concept/procedure here is quite easy but if things aren't moving freely, it can be a real PITA.

1. I think that you can simply loosen the coupler bolts to check for alignment but if you need to adjust (or by more than "just a little"), I would suggest removing them at that point. One problem I had was that by not removing them, the bolts and the "lip" of the flange would interfer with proper measurements/alignment. I chased my tail for a while here.

2. I needed to adjust the "yaw axis" but the engine mounts would not slide freely on the trunnion pins. Age and corrosion were certainly part of the problem here but I suspect that the trunnion pins are somewhat "locked" in a parallel horizontal axis. After a few bashed appendages, I needed to change course. I was also going to need to make a vertical/pitch axis adjustment so I released the locking nuts and made some adjustment there. Then, things finally started coming together and I was able to move things more freely horizontally on the trunnion pins. So my take away here is that you need to release the locking nuts to allow the trunnion pins to turn a little about their "yaw axis".

I hope that from here on out, I'll mostly just need some minor vertical adjustments, in which case this will be a piece of cake!

After breaking a shaft, I had to of course do an alignment. (because being out of alignment was undoubtedly the cause of breaking the shaft in the first place).

it's certainly like an upside down geometry puzzle on a v-drive. It was way easier on my direct drive! My front pins were so seized that I literally bent my prybar. But I was able to get all the necessary adjustments on the rear. I was starting to get disheartened thinking I'd never get anywhere close to that magic 0.003" but I started to get close after a while and once I got within spec, I STOPPED messing with it and locked everything down.

Hi I want to check the shaft alignment on my boat. I found this video on youtube: https://www.youtube.com/watch?v=5UqniaiggKA.

In this video the guy says that the clearance between the shaft and the shaft log ( where the shaft goes though the hull) must be checked.
So do I have to remove the dripless shaft packing to be sure that the shaft is in the center of the shaft log or just by removing the coupling bolts the shaft will be in its natural position and automatically there will be a clearance between the shaft and the shaft log?