Shaft coupling - help with stuck set screws

[Knotical]

I have to change my prop shaft and I was able to loosen the stuffing box and disconnect the shaft from the transmission. The coupling has a significant amount of rust on it and there are 2 square head set screws that seem frozen and I can't remove them - any suggestions on how to get them out? I placed some penetrating fluid on them and intend to use a heat gun tomorrow.

Also, once the set screws are removed how easy/hard it is to remove the coupling? I don't have a lot of space in there to get a pulling device (one that attaches to the coupling flange and requires a bolt to be tightened) in.

Worst case I can cut the shaft between the coupling and stuffing box but would avoid it if possible. If I do have to cut it what kind of disc (I have an angle grinder) will I need to use? The shaft is bronze.

Thanks for your help.

Darshan

[skipperpete]

Hi Darshan
Damn , it seems a shame to cut the end off a bronze shaft, why are you replacing it?
Try carefully heating the coupling and keep working on the set screws but be assured that getting the screws out is just the beginning.... that coupling will probably put up quite a fight before it comes off the shaft. If you need more space to work you can cut the rubber hose that joins the stuffing box to the stern tube, this might allow you to pull the shaft back a couple more inches.
If the shaft is absolutely due for replacement, by all means just cut it off through the gap between the coupling and the stern gland and if you use an angle grinder make sure it’s a variable speed unit and go at it slowly and methodically, rotating the shaft and cutting a slot all the way around it rather than trying to go straight through in one cut. Safety first[emoji844]

[Knotical]

Thanks for the response.

The shaft is significantly corroded and the surveyor recommended to replace it last fall but since it was so close to season end I just let it be. Now, before launching, I want to change it with possibly a new coupling and bearing. The prop seems to be ok, will have it checked and serviced.

I like the idea of cutting the hose to gain some room.

[gears]

we have an expression in the heavy equipment industry"Heat it and beat it"! I would use PB blaster, heat it and tap on the end of the set screws to break up the rust. if you take your time it will come apart.

[keepondancin]

I had to replace the bronze shaft many years ago. Tried heat on the coupling, dry ice on the shaft. Took a socket and put it against the shaft, inside the coupling, and tried tightening the coupling faces, nothing. Admitted defeat, got a friend who has a marine service, he used a Sawzall to cut he shaft right by the coupling. Took the coupling to the shop, heated it and beat the shaft out with a hammer and punch. Probably took an hour after I spent days. Just cut the shaft, bronze is pretty soft and should cut easily. The corrosion is probably electrolysis and has lost it's integrity.

[Minggat]

I got some all threads long enough to allow to sandwich a socket that would fit inside the coupling as the coupling was moving off of the shaft. I then started torqueing the nuts evenly to pull the coupling and the trans flange together. I had the same as you show in the photo. Minimal naked shaft.

[Michael Carroll]

Since you are replacing the shaft anyway, just cut it. If ever there was a job for a reciprocating saw, this is it. Very easy to go thru the bronze shaft.

[Minggat]

Originally Posted by Michael Carroll

Since you are replacing the shaft anyway, just cut it. If ever there was a job for a reciprocating saw, this is it. Very easy to go thru the bronze shaft.

Unless the OP plans to replace the coupling, he still need it off of the shaft.

[delmarrey]

Just cut the shaft and replace it with Aqualoy 22. Couplers are not that expensive. You may want to get the new coupler faced while mounted on the shaft anyway, to true it up, if needed.

Don’t waste your time on trying to save scrap metal.

https://www.propellerdepot.com/a22-shafts

[mlydon]

Looking at that shaft, you don’t have a choice - cutting is your only option. You don’t have room to get a shaft puller in there.

The good news is that it will be easy to cut. I did the same thing on a drones shaft in a cape dory 28. The bronze is much easier to cut than stainless. Bi-metal hacksaw blade on a sawzall and you’ll be through in less than a minute. Deburr the cut end, then pull it out the stern

Matt

[dick sargent]

Re. frozen allen screws. To add to the other good suggestions, I corrected my shaft log leakage by replacing the old rubber-embedded engine mounts. Under load the old mounts aloud the engine to twist and lose enough alignment to cause the shaft seal to leak.

[dennismenace111]

Heat the flange with a torch or strong heat gun. Dry ice the shaft as close to the flange as you can get it.

[caffel]

Force the shaft out w minimal effort.
Do what you can to loosen the set screws as suggested above.
Then clear whatever is aft of the coupling so as to separate the two halves of the coupling by about 1 -2 inches.
Push the shaft aft to draw the coupling apart and insert a socket wrench socket w OD smaller than the shaft.
Then insert and slowly tighten longer (grade 5 or 8) bolts through four coupling bolt holes to 'compress' the socket and push the shaft out of the coupling.
CA

[Boatyarddog]

Originally Posted by navdi

I have to change my prop shaft and I was able to loosen the stuffing box and disconnect the shaft from the transmission. The coupling has a significant amount of rust on it and there are 2 square head set screws that seem frozen and I can't remove them - any suggestions on how to get them out? I placed some penetrating fluid on them and intend to use a heat gun tomorrow.

Also, once the set screws are removed how easy/hard it is to remove the coupling? I don't have a lot of space in there to get a pulling device (one that attaches to the coupling flange and requires a bolt to be tightened) in.

Worst case I can cut the shaft between the coupling and stuffing box but would avoid it if possible. If I do have to cut it what kind of disc (I have an angle grinder) will I need to use? The shaft is bronze.

Thanks for your help.

Darshan

Ouch, a bit tough.

I don't know how you can ever replace those packing gland sealing rings.

I'd start by loosening your packing gland nuts, and backing the locknut off then tighten the packing nut maybe you'll see the shaft then.
You'll need to raise the rear of the engine to get the coupler off anyway.

The set screws will need significant heat to get them off or they'll break,
A heat gun is useless. They are mild steel so drill out till you see some bronze bits.

You need mapp or oxy/acetylene for the heat, heat and rap with a hammer and penetrant, use Kroil.

They may come out or break, drill out if you have to, if it's bronze, the shaft, you'll see bits of bronze when you get the set screws out.

Then, you'll need clearance between the two faces, trans and coupler face, to get a nut between the faces, positioned on the shafts, trans and prop shaft.

Then use bolts and nuts or progressively longer bolts to cinch the faces together, till the shaft begins to be pushed out of the couplers bore.

If it's not working, heat and try again penetrant rap on the coupler.
If it's still not working you may need to slice it apart, with a die grinder and cut off wheel.
Pull the shaft out of the coupler, from the outside, with slide hammer, don't bang it to hard, just enough to get it moving out.
Replace the coupler upon reassembly.
IMHO, I'd reposition the engine on the bed to accommodate a spacer or disc to help with getting sufficient distance to repack the gland when you need to.

It's all to tight in my opinion. If your changing the shaft, just cut it with a saws all when you get clearance, possible to raise engine rear, remove prop and push forward to get enough room to cut the shaft in two and remove.
SV Cloud Duster

[sandy stone]

To anyone who contemplates forcing the coupling off of the shaft by drawing up the coupling faces with a spacer in between (and I have done this myself), go at it slowly and carefully. There is a real possibility of bending or breaking the coupling half on the transmission side, and you will be very sad if that happens.