Conference unifix::sailing

    I had a similar problem last year.   My coupling hadn't been off
    in 20 years and my stuffing gland needed a rebuild so here is what
    I did.
    
    Go to some friendly welder and scrounge a piece of 1/4" mild steel
    just a bit bigger than your coupling.   Drill and tap holes that
    match the bolt circle on your coupling.   My coupling was three
    3/8" holes so I tapped the plate with three 3/8"-24 holes.
    In the center of the plate tap another hole (size is not critical
    but it should be big and can be course threads.  I used a really
    hungry 1/2"-13   ( I think it was 13 anyway).
    
    You will need a supply of various length cap screws for the bolt
    circle and some lengths of threaded rod for the center.  Use the
    threaded rod to 'extend' a push rod from the plate into the end
    of the shaft as you draw the plate against the coupling with the
    cap screws.
    
    You now have a homemade, low profile, customized (no patent applied for)
    coupling puller.  By alternately making no pressure adjustments
    to the center screw and high pressure fine adjustments with the
    bolt circle screws I forced the shaft off of the coupling.  In my
    case I didn't dare use heat (wooden boat and gasoline engine).
    I used a lot of penetrating oil and the whole process took me almost
    two days.   Tap the coupling with a hard wood mallet once the pressure
    has been clocked up.   This helps the oil penetrate the fitting.
    
    I wouldn't try pushing the coupling back on the shaft.   You will
    be jamming any burrs or contaminants under the surfaces and I think
    you could get hopelessly stuck this way.   Good luck.   You will
    be exceedingly proud of yourself after conquering this metallic
    monster problem.

Banging on the shaft coupling to remove it from the propeller shaft is 
unlikely to do anything other than damage the coupling. 

The key that fits in the matching grooves in the shaft and coupling is to keep
the shaft from turning inside the coupling. A hardened set screw (along with
corrosion) keeps the propeller shaft from pulling out of the coupling. [Note:
These set screws tend to loosen, and when they do, the propeller shaft may
come out of the coupling. A small hole should be drilled through the head of
the set screw (which is difficult to do since the screw is hardened). A piece
of wire can then be poked through the hole in the set screw, passed around the
coupling, and the ends twisted together. This will keep the screw from
loosening. Use stainless steel wire if you can get it.]

After removing the set screw the propeller shaft can be removed from the 
coupling with a bit brute force carefully applied. Get a piece of 1/4" or 
thick steel plate or 3/8" or thicker aluminum plate or even a thick piece of 
oak or other hardwood. Drill holes in the plate that match the bolt holes in
the coupling. Get a piece of round bar a little smaller in diameter than the
propeller shaft and a bit longer than the coupling (I used a deep socket
wrench). Get four long threaded bolts (or lengths of threaded rod) and some 
nuts the same diameter as the bolts used to clamp the shaft and transmission 
couplings together. 

Put the bar against the propeller shaft and connect the plate you made with
coupling so that when the bolts (or threaded rod) are tightened the bar pushes
the shaft out of the coupling. Slowly and evenly tighten the bolts to push the
shaft from the coupling. You may have to get the bolts very tight to break the 
corrosion bond. 

Once you've removed the shaft from the coupling, clean all the rust and other 
corrosion from the shaft and the inside of the coupling. Before putting them 
back together coat all the surfaces liberally with something like Never-Seize. 
This will make future disassembly much, much easier. 

Also, adaptations of this idea can be used to remove propellers from propeller 
shafts and cutlass bearing from struts. 

    RE.1 and .2: Thank you guys.It looks like I'll do it the way you describe.
    It seems so simple and effective way to take of the coupling from the
    shaft.Now...how didn't I think of that?
    On a related matter, I called Mac Boring(Yanmar dealer)to check if I
    needed a special torque wrench to tighten back the loose Lock nut to
    the output shaft and I was told I can rent one from an automotive
    store or any tool rental outfit that may have one.Really?
    I was also told to Purck(sp)punch the Lock nut after I tighten it so it 
    doesn't come loose again.How you do that? Hitting on a pipe against
    that nut with a hammer?? Any feedback please.
    Nice country!!
    

re .3:

Torque wrenches aren't all that expensive. I'd suggest buying one as it is 
a both useful and necessary tool for much engine and other work.

re prick punch: This is cheap and dirty and not all that good. Clean the 
nut and shaft with acetone and use Loctite (a chemical anaerobic thread 
locking compound available in automotive stores everywhere). Much better.

    Loctite suggestion is a good one but be very sure about the cleanliness
    or it won't work.   If you still decide to use a punch this is simply
    done using a center punch intended for metal work.
    
    Just take the punch (and hammer) to the inside edge of the nut at
    several locations.   The object is to make several depressions
    in the steel where the shaft thread meets the nut thread.  You're
    basically just screwing up the threads.   Its not too elegant but
    it does have the advantage of price.
    
    

re .5:

Using the center punch is cheap until the next time you have to remove the 
nut! Repairing damaged/distorted shaft and/or nut threads might not be either 
easy or cheap. Better to spend a few dollars for some Loctite. This is one of 
those times high tech is really better.

You probably dont want to hear this, but...

I collect old prop shafts whenever I see one around the boatyards. I use the
material in my shop to make various parts. I have one old shaft and coupling
which has become somewhat of a challenge. Its been under my arbor press,
heated near red with torches, hammered, cursed, etc and is still firmly
attached to the shaft. Ive sawed the shaft off, and used the stock, but I keep
this old coupling around, cause someday Ill get the damned thing apart!

Someone mentioned getting props off. This is a bit of a different problem,
since props are on a taper, not a straight shaft. The trick for a prop is
two very heavy hammers. You hold one against the side of the hub, between
the blades, and whack the hub between two other blades. Usually just a couple
hard whacks and the prop jumps off the taper.

Good luck getting your coupling off!

    re. 7:
    Gee! you spoiling the fun :--)
    Well, I hope I don't have the problems you describe, but again with
    my luck...
    Anyway, this week end I am going to meassure  the location of the
    holes on the coupler so during next week to make the template home.
    (cannot do it there,no electicity in the yard to drill.)
    Next week end I will do the operation.Afterwards I'll post the 
    results here.
    If things don't go right you can hear my screams if you happen to
    be on the Newport bridge at that time.

re .7:

If brute force doesn't work, you're not using enough of it!

    extension to .9
    
    NEVER force anything! get a bigger hammer !!!
    Don

    The operation of taking the coupling out came to a succesful conclusion
    last Saterday,but after a lot of effort and sweat mostly because of
    lack of space to work.The way that everything now is disassembled
    presents the opportunity for me to install also a Last Drop stuffing
    box.Thanx everybody for your help.
    Now let's see what problems lies ahead on the assembly.