Anti seize on coupler set screws?

[skunther]

Got it. Slight imperfections throw everything off at 2700rpm.

So here’s a question: I notice a slight jiggling of the coupler and shaft when idling (resonant frequencies?), but things seem a bit smoother at higher rpm’s. Should I have the coupler/shaft balanced (is this done?) or the surface inspected for any warble (like a brake disk)? I’m not sure if the slight shaking I observe at idle is normal or something to be concerned about.

 

[dlochner]

Can you clarify what you mean by this? Why would it need refacing, and how does it save the shaft?

I have a 1” shaft with a Yanmar transmission. Couldn’t I put a 1” split coupler with Yanmar bolt pattern on without any further modifications?

Ideally when attaching new shaft and coupler a machinist should fit and face the coupler and shaft. This ensures the face of the coupling is 90° to the shaft.

The purpose of a split coupling is allow for removal of the shaft from the coupling with out damaging the shaft or the transmission. Too often shafts are hammered off the coupling which can damage the coupling or pushed from the coupling using the long bolts and socket technique which can damage the transmission.

To remove a split coupling, loosen the clamping bolts and then spread the coupling halves apart a very small amount this will allow the coupling to slide off the shaft. Protecting the coupling and shaft with an anti-corrosion spray makes the job easier.

See the link to Steve D'Antonio's article in post #2 of this thread.

 

[dlochner]

Got it. Slight imperfections throw everything off at 2700rpm.

So here’s a question: I notice a slight jiggling of the coupler and shaft when idling (resonant frequencies?), but things seem a bit smoother at higher rpm’s. Should I have the coupler/shaft balanced (is this done?) or the surface inspected for any warble (like a brake disk)? I’m not sure if the slight shaking I observe at idle is normal or something to be concerned about.

At idle everything jiggles, especially if you have a 3 cylinder diesel. The motor mounts allow some movement of the engine which will be transmitted to the shaft. Since stuffing boxes and dripless seals both allow some movement.

The video you have looks normal.

 

[Hamish_s]

For anyone still following this thread, my recent event may provide new stories. Immediately post-launch after winter this year, I took my 2002 Hunter 386 went through open water for 2 hours to get to my club. Got there, put it in reverse, and the prop stopped spinning. Had to get shepherded into my slip. Hoped it was just low tranny oil. Turns out that the previous owner had removed the key between the coupler and the shaft 8 years ago, and simply torqued down the set screws to hold it. Lasted 7 years and maybe 200 hours with me. Now, I am going to install a split coupler but have no plan to machine the faces. The end of the prop shaft has some serious scarring, but the coupler will clamp down on it, at least for the season.

 

[Ralph Johnstone]

Turns out that the previous owner had removed the key between the coupler and the shaft 8 years ago, and simply torqued down the set screws to hold it.

Somehow, somewhere in this world of ours, there has got to be a law against that sort of thing. At least there should be.

 

[dlochner]

The deep scarring from the set screw is a concern, however, not visible to the naked eye is the wear on the shaft from the constant movement of the coupling against the shaft. I'm not convinced that you will be able to clamp done on the shaft with sufficient pressure to have a reliable coupling, especially without a key in the keyway.

 

[jssailem]

there has got to be a law against that sort of thing

One can hope for KARMA.

 

[jssailem]

I notice a slight jiggling of the coupler and shaft when idling (resonant frequencies?)

It is a mature diesel engine. They are not immune to a little jiggling. At 800 rpm (not exact as I need to recalibrate my tach) there is a little vibration. At 1000 rpm and beyond the engine smooths out.

What I seek is smoothness going in and out of gear. No wobble of the shaft (you can test for a bend in the shaft). I had that done on my new shaft. The prop, shaft and coupler were "fit and faced" by the machine shop providing the shaft and coupler, in Everett.

This background may be informative. Guide To Marine Propeller Shaft - DEK

 

[Tally Ho]

Is there a reason you cannot put a key in the key way?
Do you plan to replace the shaft at the end of this season?

Sounds like you should make sure your Tow US membership is paid up.

Greg

 

[rgranger]

Is there a reason you cannot put a key in the key way?.

Greg

From the photos it looks like the Key groove is gnarled

 

[Tally Ho]

From the photos it looks like the Key groove is gnarled

Agree….but even part of a key in there is better than no key. Those divots from the set screws look pretty bad and I think will continue to deform around the shaft…eventually failing.

Greg

 

[dlochner]

Agree….but even part of a key in there is better than no key. Those divots from the set screws look pretty bad and I think will continue to deform around the shaft…eventually failing.

If the shaft has not worn evenly, i.e., the shaft is no longer round, it will be more difficult to develop enough clamping pressure to ensure the shaft does not slip in the coupling.

Replacing the shaft sooner rather than later would be prudent. That, and get unlimited towing.

 

[Tally Ho]

If the shaft has not worn evenly, i.e., the shaft is no longer round, it will be more difficult to develop enough clamping pressure to ensure the shaft does not slip in the coupling.

Replacing the shaft sooner rather than later would be prudent. That, and get unlimited towing.

And put a zinc or something inside the boat or in front of the P bracket to keep the shaft from spinning right out of the boat!

Greg