Vibration issues

[Unchained]

I’m having vibration issues and read some posts on alignment problems, cutlass bearing wear and of course prop damage. Starboard engine/trans were replaced last year, aligned dry, but not after going in the water which I read is the correct procedure. We looked at the alignment of the couplings yesterday and the starboard side was out, left to right by approx.. .04”. The shaft, when apart, had some play too, basically left to right and up and down maybe 1/8” or so. Is this normal or should it be rigid? By the way, I noticed a little puddle of water under the log/shaft seal too. (port side was dry) We shifted the mounts around and got alignment closer to about .02”. How close is close enough? I’ll do a test run this weekend and see if this made a difference. My plan is to replace the shaft seal and cutlass bearing before next season, at least on the starboard side, but maybe I’ll do both. What is the best product out there to use for the shaft seals? Are there any that help with slight misalignments? What about adding a flex coupling too? Any recommendations/suggestions would be greatly appreciated.
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Thanks. Mike

[jav]

If your measurements are from feeler gauges between the flange faces, .040" is terrible and .020" is still too much. I usually align to within .003", but some guys are fine with .007".

Also-no disprespect intended- but given your question about wether the disconnected shaft should have some free play- it sounds like your not too familiar with a single strut shaft system and I'd recommend getting some experienced help with alignment. There's quite a bit to understanding how to get and interpret the numbers, especially in determining if you have a true alignment problem or a bent shaft/coupling face problem.

I can't stress how important it is to get this right not just from a vibration stand point but this will also impact the life of the cutlass bearing, the transmision bearings even shaft life can be severly decreased through cyclic fatigue.

[Unchained]

I'm not offended at all by your reply. I appreciate honesty. I'm mechanically inclined when it comes to engines, transmissions, etc..,but no expert with this type of single strut shaft system and alignment, only what little I have read so far. I'm just one of those guys who likes to take on anything. I'll get an experienced marine tech to help me out with this part.
Any suggestions though on replacement shaft seals or flex coupling?
Thanks.

[Big D]

......aligned dry, but not after going in the water which I read is the correct procedure.....starboard side was out, left to right by approx.. .04”. The shaft, when apart, had some play too, basically left to right and up and down maybe 1/8” or so. Is this normal or should it be rigid? By the way, I noticed a little puddle of water under the log/shaft seal too. (port side was dry).....What about adding a flex coupling too?....

Jav is correct; you want to find out what is causing the vibration and remedy before you damage other hardware.

Aligning dry only and not in the water after is incorrect in my opinion. Get as close as you can out of the water, then let the boat sit in the water for a day, then do final alignment in the water.

When you say out left to right by .04, I`m thinking you`re talking about coupler to flange outer edge alignment; should be centered. I say that because the outside diameters of the coupler may be different than the transmission flange, otherwise, the mating surfaces of the shaft coupler and transmission flange should be within .003in. of each other. When uncoupled, it is normal to be able to move the shaft up, down, and sideways in the tube, the shaft is not tight to the tube, only the packing, so the wieght of the shaft alone will cause it to drop in the tube. You must keep this in mind and find the center when doing your alignment.

Unless you have dripless shaft logs, it is normal to have some dripping.

My advice is to remove both shafts, props, and couplers, then send into the shop to have them checked and tuned. While these are off, check the strut bearings and replace if needed.

The above will eliminate shafts, props and couplers as culprits. To eliminate the transmission flanges; unbolt the coupler from the flange but keep them mated together. Now take a feeler gage and pick a spot like 12 o`clock and take a reading between the two. Without allowing the shaft to turn, rotate the transmission flange 90 deg and take another reading at 12 o`clock again while keeping the surfaces mated. Repeat until you get back to the first spot measured. If the measurements change, the flange is bent and no matter what you do with the running gear, the alignment will never be right and the potential for a vibration will exist.

There is a proper method to putting everything back together, and I recommend checking in with us when you`ve confirmed the gear is true. Don`t take shortcuts here or you`ll be back at it and cut into your boating time, another haul out $$, etc etc. No need for flex coupling if done right!

[Unchained]

Hello everyone. I finally had her pulled yesterday and took a quick observation this morning before going to work. The starboard side rudder has some play in it. I can move it front to back a good 1/4" or so. I'm guessing the bolts are just loose. I see an access panel that I can take off to get a closer look. I also noticed that one of the blades on the port side prop must have hit something and curled about 3/8 of an inch of it over. I'm sure this is something that can be repaired and should be balanced too, right? Normally with some smaller boats I have owned, I would just buy a new one, but these are expensive. There was also some very slight play in the port shaft when I moved it up and down. I couldn't get very good access to it to check it further, but I will this weekend. I'm hoping the loose rudder and bent prop are the bulk of my vibration problems here. What do you guys think?

Mike

[davescarrs]

I think you mean the strut (the brace that holds the shaft and contains cutlass bearings). If there is play in there the cutlass needs to be replaced.

I had a vibration problem, too. I had the props done by a prop shop and I changed the cutlass bearings. To do the cutlass bearings I had to remove the shaft, therefore take apart the shaft flange from the trans flange. It is always a good idea to mark the alignment between the two, in that you are able to duplicate the way the holes lined up between the two. I did not do this and had to adjust after running and visibly seeing the shaft have a wobble. Re positioned the holes and the problem was solved.

A good website for details on removing shaft flange from shaft and doing cutlass bearing was pbase. Google it.

Good luck!!

[Unchained]

Thanks for the information, that Pbase web site is awesome! Cutlass bearings look very easy to replace. I was looking at ones that are available from Morse. Does anyone know which part number I need? Removing the collar from the driveshaft looks like it could be difficult. Mine probably has not been removed in at least 10+ years is my guess. I took a quick look and it doesn't appear to be pressed on, because there's a built-in clamp with two bolts that secure it to the shaft. I'm thinking it has to be pressed on too though considering how tight the tolerances need to be. Any recommendations for getting this removed before I get into it? I was going to make a steel piece with the same bolt pattern and have a solid pipe in the middle, then tighten the bolts evenly to slowly pull the collar off. Does this sound like a good method?
In regards to my starboard rudder that is loose, I found that all of the play is coming from the top bushing that is located inside the boat. It actually looks like just a piece of wood, but there has to be some kind of bushing inside. Does anyone know what I am referring to and where to get a replacement?
Thanks. Mike
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[BobCT]

Mike,

I just replaced a cutless bearing (correct spelling if you're searching) on my mid cabin yesterday. The easiest way is to remove the strut which really isn't a big deal, just the six bolts. It probably could use a re-bedding anyway. I think that's easier than dealing with the shaft coupler but have done it both ways. If you choose that method, that's essentially how you separate the two. I used a socket in between and kept alternately tightening the bolts until it presses out.

I have the old bearing on the bench and will measure and post for you. Removal and reinstall isn't a big deal as you've seen.

On the rudder, I think they made a model year change. My '88 does not have the bearing you're referring to but Todd Pote's '87 does. The 88's only have a thin/nylon bushing which looks like a top hat. I used two to eliminate the play. The rudder play wil cause a vibration so you could be onto something. The other area to look is the tiller arm connection which if it's loose (and probably is) will cause the same. If you search youtube for the video I posted I mentioned how I fixed that issue (delrin bushing insert).


Bob

[larryeddington]

When reinstalling a press fit coupler on the shaft, heat in oven (wifey must be away) to 350 degree, it will almost drop on the shaft with a slight tap if done delibertly (don't delay shaft will warm from coupler). Worked easy for me.

[davescarrs]

Pbase also has photos and instructions on removing the flange from the shaft- essentailly it is the same way BobCT described. It is not difficult- but a pain in the a$$ as far as labor goes and getting your body in there. To put flange back on I had to whack the flange repeatedly with a small sledge as I spun the thing it took a long time. Perhaps the struts being removed would have been easier as long as you can get to them from the inside (if needed). On the Trojan INT 10M I have there are two struts on each side, each with a cutlass bearing. the front bearing actually has a smaller circumfrance than the rear one, which would allow you to slide the front one thru the rear shaft and then slide it up to the strut it belongs on.

Also putting the new cutlass bearing in was no problem as far as being able to tap it in. I used white bar soap to lube a little and it went right in.

[BobCT]

Installing the coupler.... I did it the same way and my prop guy said "NO", don't ever hammer the coupler back onto the shaft.

Use a block of wood and a small sledge and drive it it on at the prop end. No risk of doing anything to the flange and is easier in my opinion. You need somebody inside the boat though....


Bob

[davescarrs]

I too heard to go from prop end with sledge and wasted an hour or two and just couldn't get it to work that way. Went from other side (engine room) to get job done.

[larryeddington]

As I said earlier Heat the coupler and not the shaft will go on easy, and does not damage the coupler!I have used this method to install interference bearings but limit to 250 degree for them as full of grease and heat treated.

I will tell this works and makes this a simple porject to replace the coupler on shaft.

[davescarrs]

Larry
When I first saw your post I did not "read" it. I assumed the heating you were talking about had to do with the cutlass bearings going in the strut.

Now..having read the post, that sounds like a great idea that i wish i would have read before having to tap my coupler on the shaft. Definitley sounds like it would work great.

[larryeddington]

A hot coupler definitely works well and prevents damage from blows. Also others have suggested as the way to put in a cutless bearing by freezing the bearing, ergo it shrinks and easier insertion and minimalizing any potential damage. I made an installer and rmover tool using all rod and farm tractor implement pin adaptors. It pushed out fairly easily and putting in will be a piece of cake especially with frosty bearing.

Heat and cold can be a very powerful alley.