Shaft Wobble and Flexible Coupling

[HalfHourEarly]

My Viking 33 has developed a severe vibration in the shaft and I can see a very clear circular wobble in the shaft. It looked like a bent shaft but I haven't hit anything and there's nothing entangled. Misalignment seems unlikely because it just happened with the beginning of the season. My cutlass bearing does need replacing soon but it's just showing early signs of wear.

So... I have discovered today that I have a Federal Flexible Coupling on the shaft.

http://www.henrysmith.com/couplingsfederal.htm

http://www.gpcprop.com/pdf07/Federal%20Flexible%20Couplings.pdf

This should be helping the situation but it seems that over the winter it has seized in a position that is slightly off centre. I'm not sure if the inner sleeve has seized onto the outer or if the rubber bushings have simply hardened over the years and is now holding the position that it was stuck in over the winter.

My problem, if anyone has some ideas, is how to get this thing to release (getting it off the shaft altogether in its rusted state will likely require that I pull the engine out). If anyone has one or has seen this I would appreciate the help.

Thanks

[Mike Jenkins]

Hi there - Half hour early;

I wonder if based on the name your boat is from Newfoundland (because of time zone).

I recently removed my shaft and also have a "drive saver" flexible coupling. Although I removed my A4 engine for a rebuild this winter first, I was able to remove the shaft by disconnecting the three bolts from the coupling and then using a 3 jaw gear puller removed the coupling from the 1" shaft. In my boat the shaft with the propeller was able to be pushed back 8-10" from the motor, until the coupling came in contact with a keel bolt oter wise the shaft could be pushed ack until the coupling contacted the stuffing box. The drive saver is connected to the motor output shaft with allen key screws requiring penetrating oil to break free.

I was able to replace the stern, cutless bearing in the brearing holder on the stern post, by sawing and chieseling the old bearing out ( more work than removing the motor).

I suspect removal of the shaft and an examination of the flexible coupling will allow you to determine if the shaft is bend possible to lifting out of the water last season or a problem with the coupling.

I have a slight problem with the alignment since the shaft was offest to the side of the motor I'm hoping the flexible coupling will reduce the strss until I realighn the motor to the shaft. I believe I may have mis aligned the new cutless bearing.

Regards,

Mike Jenkins, Nova Scotia

[HalfHourEarly]

Mike

Good detictive work. Yes, I am in Newfoundland.

I am hoping to get the whole assembly out when I lift out again but right now I am hoping that things will free up without too much tear-up. In this assmbly, normally the engine is isolated from the shaft by the rubber trunions that house the three main bolts. This would mean that there would be no need for shaft anodes. However, I do have them and they do corode. This has led me to the conclusion (theory) that the inner metal sleeve and the outer metal sleeve are now contacting eachother and are rusted together.

My unit seems to hold the shaft with a key (not visible) and a set screw (very coroded) .

Short of disassebly, it is seeming more like my option is to find the best cutting oil to help break the contact. Help greatly appreciated.

[Wes]

Mike

Good detictive work. Yes, I am in Newfoundland.

I am hoping to get the whole assembly out when I lift out again but right now I am hoping that things will free up without too much tear-up. In this assmbly, normally the engine is isolated from the shaft by the rubber trunions that house the three main bolts. This would mean that there would be no need for shaft anodes. However, I do have them and they do corode. This has led me to the conclusion (theory) that the inner metal sleeve and the outer metal sleeve are now contacting eachother and are rusted together.

My unit seems to hold the shaft with a key (not visible) and a set screw (very coroded) .

Short of disassebly, it is seeming more like my option is to find the best cutting oil to help break the contact. Help greatly appreciated.

Hi,

PB Blaster...I used it for the first time this last week getting my manaifold flang apart and it worked.....Lots of tapping and time..But she broke free...
I found it in a spray can at the local hardware store...
Good luck..Wes

[dvd]

Half hour early,

I read your post about your Federal Flexible coupler issue which you posted last month (6/09) Did you ever figure out the problem with the federal coupler? I checked the posted General Propellor web site and this type of coupler looks like it would work well for my situation. I've been wanting to install a flexible coupler but I have very little clearance between the existing hard coupler and the stuffing box. The other flexible couplers I've seen usually install between the 2 existing couplers. The federal coupler replaces the prop side hard coupler and therefore does not require a lot of additional shaft space to install. Just wondering if you got it working and whether you repaired, replaced or just did away with this type of coupler. If anyone has any info on this I would be very interested in it.

Thanks

DVD

[HalfHourEarly]

dvd

I still have the problem, at least to the end of this season. It has gotten a little better though. The feedback that I have received is that these flex couplings can be useful in the short term but have been problematic in the longer term. What seems to be happening is that the rubber used to isolate the vibration from minor missalignments actually hrdens over time and can actually cause shaft missalignments.

I'm not sure what I will do with it but I think I will try to eliminate the need for it if I can.

HHE

[dvd]

Well, I installed a federal flexible coupling on my late model A-4 with 2 to 1 reduction and it was quite a chore. I only had about 4 inches between the stuffing box and the engine coupling. The new federal coupling is about 2 3/4 inches. The only way I could get it on, after removing the prop side coupler, was to get in the water and pull the shaft out so that only about a half inch of shaft was exposed through the stuffing box. Because the keyway was now in the stuffing box water poured into the boat. A friend held the new coupling in place trying to keep the keyway lined up while I gently tapped the shaft back into the boat and through the new coupler, with a rubber mallet, while holding my breath underwater. The shaft did go back in but seemed to somewhat jam about half way in, as it would not move any further. I still needed it to go in about an inch more. At this point I left the new coupling set screws loose and just started up the motor leaving the boat tied up in its slip and gave it the gas in forward gear. I let it run this way for several minutes. After shutting down the engine and checking the progress, the shaft had in fact, gone most of the way into the coupling. A little more rubber mallett tapping and the install was complete.

I road tested the new set up and it was quite a difference. The flexible coupling dampened alot of the noise and vibration I had been experiencing. The federal flexible coupling appeared to be a well made unit and looks like it will last for some time.

You can look up the coupling on line to see if it will work for you. Just remember, if you have the same close quarters as I have either pull your boat first or do it in the summer months as swimming will be required. Wish I had a video of this.

DVD

[respite]

Hello DVD,

What was the part number of the federal flexible coupling you used? I'm looking into installing one in my boat and I just wondering for reference.

cheers,
Respite Catalina 30 78

[dvd]

Flexible Coupling

Respite:

Go to the top of this thread and check out the links placed there by half hour early. That's how I found out about the federal flexible coupling.

DVD

[respite]

Aligning the A4

Thanks DVD.

My engine certainly needs to be aligned. The problem that I have is, how do you guys recommend moving the big heavy engine around? Do any of you have any recommendation or techniques that you can share in how to move the engine during the alignment process? I need to find a leverage point where I can used a crow bar or maybe a car jack or a come-a-long to move the engine side to side.

Any suggestions and/or pictures are welcome.

[msmith10]

My experience has been that it's more difficult to hold the engine still while aligning, tightening mounting bolts, etc, than it is to move it. You're just moving it tiny amounts. The tiny amounts that you're moving it during alignment can be attained just by prying against the block with a long screwdriver, wooden handle, or by tapping the block with a rubber mallet.