Prop shaft removal

[lumphammer]

I need some advice on best way to get my propshaft out. I am stuck at the point where I am trying to release the inboard end of the shaft.

I have a 25mm stainless propshaft which has a 50mm (diam) x 75 (length) (approx) boss on the end. This bolts to the gearbox with three bolts equally spaced around the shaft and parallel to it. These are all undone.

The boss appears to be keyed onto the shaft, and locked in place with two allen screws. The allen screws are totally rusted up, and don't want to move.

I want to replace the shaft so I am thinking to drill out the allen screws and use a bit of brute force (hammer) to knock the boss off the end of the shaft?

I want to keep the boss, as I will need it to refit the new shaft.

Any pointers one how to proceed gratefully received?

TIA

 

[pete]

Hi
If you are replacing the shaft can you not cut the shaft off inside the boat and then remove the flange in a vice,I know it won`t be easy to cut in situ but it may save damage to the flange and to the stern gland through knocking.
Failing that is it possible to apply heat to the flange (safely) to hopefully free the allen screws.
Pete

 

[erwinc]

Hi,
I experienced more or less the same problem on my Trapper 500 last winter.
This trick worked out fine: I did put a bolt of the right lenght between the shaft and the coupling and I did EVELY thighten the original coupling bolts again.
That way the bold acted as a spacer and it pushed the shaft out, without using a hammer or other brute force.

I hope my explanation is clear to you, as English is not my native language.

Good luck!

Erwin

 

[rogerthebodger]

After drilling out the allan screws (drill slowly allan screws are hardened) use a sprocket puller to remove the boss

 

[deejames]

Along the lines of ErwinC's reply ....... get some studding the same size as the original bolts and cut into three lengths about 6" long, and half a dozen nuts to fit. Move prop shaft back the maximum distance possible and use a spacer (a 20mm diameter socket for example) between the flange on the gearbox and the coupling. Use the thre lengths of studding to "pull" the flange back towards the gearbox, and - with luck - you will push the shaft out of the coupling. I bit of heat from a blowtorch during the process might help if it isn't too dangerous ! Of course, this assumes that the coupling is "hollow" and the end of the shaft is roughly flush with the inboard end of the coupling.

 

[sailorman]

Hacksaw the shaft done my old Co 32 with a junior h/s in 1/2 hr in a vvery confined space

 

[Poignard]

Yes , that's worked for me also. Try applying Plusgas as well; it's surprisingly effective.

 

[Graham_Wright]

DON'T HIT IT! It is probably cast iron and will shatter. What you need is a puller. A simple disc with four holes to line up with the holes in the flange and a centre tapped hole to take a bolt. I would suggest M24 (and fine if possible), Attach the puller with four bolts to the drive flange, wind in a centre bolt to rest on the end of the shaft (keep it all square), tighten as tight as possible and then clout the end of the bolt smartly. If it is safe to do so, the application of some heat may help. If you have used WD40, it will probably ignite.

If you get stuck sourcing a puller, pm me.

 

[cliff]

FWIW, I would be very careful about either pressing/pulling the shaft out before removing the grub screws for the following reason:
You say the shaft is keyed into the boss - fine that takes care of radial movement. ie when the boss turns the shaft has to turn as well. Now what stops the shaft moving along the axis of the boss? when going ahead that is not a problem as the thrust from the prop is pushing the shaft into the boss but when going astern the thrust is in the opposite direction ie the shaft is being pulled out of the boss and this movement has to be restrained. Two standard grub screws are not going to go the job for long so I suspect the business ends of the grub screws are conical (pointed) and fit into matching recesses drilled or otherwise machined into the shaft so there is a mechanical restraint rather than relying solely on friction grip.

I cannot see the restraint of the fore and aft movement of the shaft relying on the friction produced by two flat head grub screws alone - there must be something else hiolding the shaft inthe boss otherwise you could not transmit the thrust to the gearbox. Above is only my opinion of course.
--------------------

"Artificial intelligence is no match for natural stupidity"

 

[Graham_Wright]

My Halyard (not theirs really, but can't remember the name) flexible drive flange is a split sleeve and is very tight on the shaft. A puller is the only way to extract it.

BTW, be wary of any suggestions that might involve putting a bending force on CI;- it is not strong in tension and may fracture.

 

[cliff]

Use a puller after removing the bolts that hold the split boss together? I too have a split boss on the drive train on my boat but there is no way on god's earth to remove the shaft until the 4 bolts have been removed as they slide into mating slots machined into the sides of the shaft to prevent foe and aft movement of the shaft (they also prevent rotation of the shaft in the sleeve.
--------------------

"Artificial intelligence is no match for natural stupidity"

 

[Aja]

I suspect that the suggetion to sever the prop shaft and slide it out aft may be the only way forward. i had to do this on a previous boat. Bigger the hacksaw blad the better - but space may be at a premium. Leave as much shaft in the boss as possible.

Once the shatf and the boss are out of the boat you should have a much better chance of separating the boss from the length of shaft remaining, using heat / release oil / pressure.

Using a spacer in a vice would be much easier too.

Having more space will show if the above is having any effect.
Donald

 

[uforea]

The flange on my boat was secured to the shaft by a 22mm nut inside the flange itself and the grub screws were designed to stop this large nut from unscrewing.
Ted.