How to pull prop shaft?

Steve, I have read somewhere that it should be possible to pull the shaft past the rudder without removing the rudder. I tried and I found that on my '68 Mustang removing the rudder was necessary. It turned out however, to be very easy to remove the rudder and while the rudder was out I sent it to a local prop shop to have a few small old cracks welded up. They straightened the rudder although it was bent very little. (Now the boat steers much easier than before.) The boat was slightly hard to turn to the right and that is no longer the case.

So what I am saying is that removing the rudder and having it checked in a prop shop might not be a bad idea anyway.

I doubt that the prop shaft can be removed from the front.

My prop shaft was bent pretty badly so I was not too worried about damage to it when I removed it. I was concerned with damage to the strut. After uncoupling the shaft from the trans, and completely backing off the shaft seal packing nut I removed the prop, screwed an old prop nut onto the shaft and gently tapped the back of the nut driving the shaft out.

After unbolting the shaft coupling and backing off the packing nut, you will have to move the shaft out about 2" to remove the shaft-half of the coupling from the shaft. The shaft coupling will have a set screw (or two) holding the coupling onto the shaft. It is not an uncommon practice to run a set screw on top of another set screw to lock it into place. So after you remove each set screw look into the set screw hole with a flashlight to make sure there is not another set screw. The shaft-half of the coupling should come off the shaft with light tapping. Make note of how far the shaft sticks out of the coupling so you can put it back the same.

It took about five minutes of light tapping on the back of the prop nut with a hammer to get the prop shaft completly out. I had to polish the shaft in front of the strut with emery cloth to remove what looked like years of crud and build-up. I then lubed the shaft with dish soap before I began tapping it out through the bearing.

One final note, for those reading this that may be replacing your prop shaft, my replacement prop shaft did not have "dimples" (or shallow holes) for the coupling set screws to set in when screwed down as did my original shaft. I cannot see anything else that positively holds the shaft in the coupling when running in reverse so I drilled dimples into the shaft with a 5/16" drill in the same position as in the original shaft. I drilled just deep enough so the the full diameter of the drill bit just bearly began to drill into the shaft. (The depth of the dimple was equal to the height of the drill bit point - if that makes sense.). To mark the new shaft so I would know where to drill the dimples I placed the coupling half on the new shaft at what looked like the correct distance, which was flush with the face of the coupling, and I tightened the set screws onto the shaft. This left marks on the shaft in the exact places where the dimples needed to be drilled. The distance of the coupling half from the end of the shaft should not be too critical - 1/16" either way should be OK because the effect is your prop is moved forward or rearward by the placement of the shaft in that coupling. So what's 1/16"?

The whole shaft and rudder replacement job, not including chasing parts, was about 4-6 hours spred out over a two week period (but I work slow and sometimes drink a little beer during these kinds of projects).

I hope this helps.

Why did you have to hit reverse so hard?

    Just curious!    -Brad-

Well, I was not paying attention like I should have and the rope came up on the skier a bit to quick. To avoid pulling the skier's arms off, I hit reverse a bit harder than usual. Bang! Damage done.

After dimpling, I have had to hit reverse hard again with no problems. What I mean by hard is that I throttle up once in reverse. I NEVER throw the tranny in reverse hard...just throttle up once eased into reverse.

Yes, we use a key. The key keeps the shaft from turning or spinning in the coupling...this is not the problem. The problem is that a straight shaft can pull straight out of the coupling...something a key will not stop. The dimpling stops this as it allows the set screws to bit into the shaft.

In other words:
key: prevents shaft rotation in coupling
dimpling: prevents axial movement of shaft in coupling.

BTW: doubled tapered shafts do not need dimpling as the nut prevents axial pullout.

79nautique said that the key is a shear key.I do not believe this is correct.