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  #11  
Old 02-29-2012
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Quote:
Originally Posted by gtod25 View Post
The coupling should go on by hand. Take the shaft and the flange to a machine shop and have them check the shaft for alignment and fit the flange. The flange should slide on/off the shaft with minimum effort. Make sure they drill a "dent" for the locking bolt, and that the bolt has a retaining wire hole to permit it to be lock wired in place.

Ref PBB, great stuff but use caution around gaskets etc;

PB Penetrating Catalyst FAQ's

Have fun.
The fit of a straight coupling to a shaft is supposed to be a an interference fit NOT a clearance fit. With an interference fit the coupling DOES NOT and SHOULD NOT just slide on because the shaft is ever so slightly bigger than the coupling. Good shafting shops, that know what they are doing, will fit them as a light interference fit.

Western Branch Metals, the largest supplier of prop shafting in the country, suggests that the shaft OD should be about .0003" - .0005" larger than the ID of the straight coupling. This will require a light tapping or heating to make it fit into place.

If you purchased couplings that fit like that, just slid on, they were incorrectly fit to the shaft. This can lead to shaft fracturing or the shaft backing out of the boat altogether.
gtod25 and jameswilson29 like this.
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  #12  
Old 02-29-2012
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Quote:
Originally Posted by downeast450 View Post
CalebD,

That is my plan. It is a tedious PITA working in that cramped space. My shaft is ss. It is moving slowly, one washer at a time, Ha! I have plenty of time to finish forcing it out of the flange this way. It has become one of the tasks that I spend an hour or two on and then leave it until the next day I am aboard. If it wasn't moving I would be concerned. I think I will change the socket for a deeper one. With the shaft already moved 3/4" it may be easier to get a socket to stay put while I bring up the bolts.

...

Taking care of the shaft is the last big chore left that came with the boat.

Down
Down,
You are a man with a lot of patience and determination. It really was torture trying to do this in the engine compartment of our Tartan 27'. I sure hope your Islander 28' has better access then we had.
If you must persist (and it sounds as though you must) keep applying the pressure evenly and methodically. There is a small chance you could deform the shaft coupling or output coupling if the pressure is uneven. There is a very long thread on the Moyer forums that details how a fellow Afourian had to replace his output shaft and get a new coupling after pressing the shaft out: Indigo - Moyer Marine Atomic 4 Community - Home of the Afourians
Good luck. Patience and persistence.
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  #13  
Old 02-29-2012
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Quote:
Originally Posted by downeast450 View Post
I expected it to "let go" before the shaft traveled 1/2"? It is well passed that! I will find out next week how many washers it takes. Anybody care to guess?
The shaft should be buried nearly the entire length of the coupling, not just a little way in - get a deep socket or a bunch of thick washers and keep going.

Lock washers are not needed, they just add a little flex to the process as you flatten them out.
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Old 02-29-2012
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Quote:
Originally Posted by downeast450 View Post
Maine, I will not "polish" it. Thanks! Heat is wonderful! Not sure how I could strike a couple of blows with a mallet. Perhaps a levered piece of 2x4 that pushes on the flange when I tap near the end?
Down, I think RC was referring to tapping the end of the propeller shaft from the outside to fit the flange back into place? Thus the many trips down the ladder he was referring to if I am not mistaken.

I am getting ready to do this exact thing to replace a stuffing box tube with a PSS dripless as soon as I can get the marina to finish the bottom job on the damn Hunter that is occupying the only available trailer.

After reading this, I am debating whether to pack a gear puller, PBB, some lag bolts and a big can of washers, or carry a hacksaw up the ladder and just be done with it.

Good luck!
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Old 02-29-2012
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JonB,

The reason for the lock washers is their outside diameter. They are small enough to fit on the bolt where the clearance to the coupling is quite limited. A regular flat washer has too large an OD.

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Old 02-29-2012
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Eric,

That makes sense! I would be concerned about the force being transmitted along the shaft to the transmission. I could fit a 1/2" steel plate between the transmission flange and the shaft flange. That would stand some whaling and pounding. Perhaps tapping? Up and down the ladder takes the place of the Stair Climber. There are so many rewards from working on small boats.

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Boil your coupling in a pan of water, and pack ice around the shaft for a half hour, before putting them together. That should make it easy. If you have heated it in place , you may have warped the shaft. Check that out before re-installing them. Put the coupling on the shaft and resurface the coupling in a lathe. Cutting the shaft key way can also warp it out of alignment.
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Old 03-01-2012
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I would recommend replacing the coupling.......Last summer I removed my Universal Diesel/Trans/coupling/shaft. My yard advised that the original tolerance cannot be maintained with an old coupling. The thin film of rust that was removed by the PBB will not allow for a snug fit once the parts are cleaned. My coupling would just slide onto the shaft with no force whatsoever. Check out Boat Propellers, Inboard Propellers, Cutlass Bearings, Zinc Anodes, Prop Shafts, Shaft Seals, and more I purchased a new coupling for my 3/4 shaft for $50-60. Installed a new packing gland while I had everything apart....... also from DBYS. The fun part is going to be aligning the flanges to a .002 tolerance....Have patience and a good set of feeler gauges. Be sure to recheck the flange alignment after 10hrs of operation.

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Old 03-01-2012
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I would agree with dry ice for the shaft and boiling water for the coupling. What about some bar or 'c' clamps (gently) applied rather than a hammer? I would be carefull not to overdo it, but I'd think you might have better luck with even pressure distributed around the coupling.

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  #20  
Old 03-01-2012
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You have to love this forum!

Let me see?

It is easy to imagine that a couple of ten thousands of black iron has washed out of the coupling as I slowly force it off with the help of PBB. I hadn't considered replacing it before I began. I confess ignorance of the type of fit involved. I expected it to "let go" because I was thinking of a tapered fit not a straight one.

I don't think the heat I applied to the outside of the coupling using a very low flame on a simple propane torch would have been enough to warp anything? I will check it.

Using temperature differences to expand the coupling and shrink the shaft will be my approach for installation.

This is a Moyer rebuilt I installed three years ago. I bolted the flange that came on the "new" A-4 up to the "old" shaft flange and used a "trick" suggested by one of my Downeast friends. Three cleaan, dry pieces of notebook paper were my feeler gauges. If all three are trapped by the flange, one at each bolt hole, as you rotate the shaft, "She will be close enough Deah!" It did work. No vibrations.

Great information! Thanks all.

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