Propshaft coupling advice

[Norman_E]

Hi. Thanks for the advice. I've been able to get a home-made screwdriver head on the screw but can't get enough pressure behind it. It pops out of the slot. I will remove the stuff attached to the engine and I've measured it all up and a socket will just about squeeze in there. It's the screw that bothers me. But I believe bristoljim might have given me the answer on that.

There is a way of loosening that screw. Get the sort of screwdriver bit that comes with an impact driver, and find one that is a good fit in the slot in the screw. Put it in place and pack Blu-Tack round it to stop it falling out. Re-assemble the coupling to the flange with the four bolts, trapping the screwdriver bit lightly so that it cannot come out of the slot, then carefully loosen it with a spanner.

 

[david_bagshaw]

what does the little ss screw go into, as it looks a bodge idea, and if the nut was loose would just turn round inside the coupling

have seen many screws that rest on the nut, but come in from 90 deg.

dissamble coupling for more room then scrape what that screw goes into, might be plastic from the look of it,, so a bit of heat on the screw, or give it a gentle clout side on. it cant be tough material as there isnt much strength in those ss screws.

then remove the big nut a few turns, heat the coupling, if afraid of overdoing it scrape some hand soap, on it. when it turns brown from conducted heat it is about 200 deg if i remember correctly, then if poss tension with a puller, and as others have said bang with 2 hammers at same time at right angles to the shaft, not along it.

 

[Deleted member 36384]

If you are going to replace the coupling consider a CV joint like the Halyard Aquadrive. The existing shaft is cut to fit an Aquadrive (or buy a new shaft) which will obviously negate the need to remove the small screw. Other advantages of upgrading to an Aquadrive are explained in the links.

Aquadrive Antivibration System | Halyard | Make Boating More Enjoyable
http://www.aquadriveusa.com/engine_mount.pdf

 

[rogerthebodger]

I have a set of these to get into difficult screws

And a set like this

 

[Mei Mac]

what does the little ss screw go into, as it looks a bodge idea, and if the nut was loose would just turn round inside the coupling

have seen many screws that rest on the nut, but come in from 90 deg.

dissamble coupling for more room then scrape what that screw goes into, might be plastic from the look of it,, so a bit of heat on the screw, or give it a gentle clout side on. it cant be tough material as there isnt much strength in those ss screws.

then remove the big nut a few turns, heat the coupling, if afraid of overdoing it scrape some hand soap, on it. when it turns brown from conducted heat it is about 200 deg if i remember correctly, then if poss tension with a puller, and as others have said bang with 2 hammers at same time at right angles to the shaft, not along it.

 

[jim.howes]

Well spotted (although it's as clear as day now that you mention it!). The R&D hasn't been in contact with the coupling has it? Thanks for the idea of the bobbin and split shaft coupling - I can't afford to shorten the length of the shaft so cutting the coupling off looks like a good option!

You say you cannot afford to shorten the shaft but I am sure if you look at the back end of your boat with the shaft back in its correct position you will have something like (at least)3" of shaft overhang which is far too much. You need no more than 1/2" to 3/4" between 'P' bracket or end of stern tube to the boss of the propeller giving extra shaft length to play with.. Another consideration is if you should need to purchase another prop shaft in the future it will be cheaper because you will need only one end machined. Jim

 

[Mei Mac]

what does the little ss screw go into, as it looks a bodge idea, and if the nut was loose would just turn round inside the coupling

have seen many screws that rest on the nut, but come in from 90 deg.

dissamble coupling for more room then scrape what that screw goes into, might be plastic from the look of it,, so a bit of heat on the screw, or give it a gentle clout side on. it cant be tough material as there isnt much strength in those ss screws.

then remove the big nut a few turns, heat the coupling, if afraid of overdoing it scrape some hand soap, on it. when it turns brown from conducted heat it is about 200 deg if i remember correctly, then if poss tension with a puller, and as others have said bang with 2 hammers at same time at right angles to the shaft, not along it.

You say you cannot afford to shorten the shaft but I am sure if you look at the back end of your boat with the shaft back in its correct position you will have something like (at least)3" of shaft overhang which is far too much. You need no more than 1/2" to 3/4" between 'P' bracket or end of stern tube to the boss of the propeller giving extra shaft length to play with.. Another consideration is if you should need to purchase another prop shaft in the future it will be cheaper because you will need only one end machined. Jim

Before sliding the prop astern I only had about an inch of room anyway as you can see from the photo. Thanks again for your valuable input in this.

 

[Mei Mac]

Success! Here's how I got there:

I had no luck whatsoever with getting the screw out.

1. Angle grinder. 'V' notch in the coupling flange all the way down to the 'retainer' which turned out to be brass.
2. Dremmell tool: cut the head off the screw and prized the brass bit out with a screwdriver.
3. Dremmell to the remaining threaded part of the screw/bolt.
4. Managed to get a socket on to the nut and a pair of mole grips on the coupling.
5. Used the flange on the gearbox to push an Allen Key against the end of the shaft. Used a grinder to create a notch in the coupling all the way down to the shaft.
6. The tapered shaft popped out!

Many thanks for all your suggestions and advice - very much appreciated.

 

[rogerthebodger]

Well done

 

[pvb]

Well done! Success at last. A boatyard would have charged you hundreds to do that.

 

[springer]

Looking at your last picture, where the taper meets the full diameter of the shaft, is that a line of dirt around the circumference, or is it corrosion? This could be a weakened area of your shaft. Suggest sterngear maker or specialist machinist has a look. Don't want to do all this work and refit a possible weakness.

 

[jim.howes]

Hi well done. where there is a will there is a way. With a little bit of Araldite and a lot of imagination you could use the coupling again. Again well done. Jim

 

[Mei Mac]

Looking at your last picture, where the taper meets the full diameter of the shaft, is that a line of dirt around the circumference, or is it corrosion? This could be a weakened area of your shaft. Suggest sterngear maker or specialist machinist has a look. Don't want to do all this work and refit a possible weakness.

I've given it a good clean and it was muck with no signs of corrosion whatsoever!

 

[david_bagshaw]

thanks forthe update

 

[jim.howes]

Hi tis I again I have made some enquires on your behalf with Hamble props. Cost of machining taper and keyway £80>£100 or whole half coupling complete £180>£200. Hamble prop phone number is 01489574222. Dave's your man. Jim

 

[Mei Mac]

Hi tis I again I have made some enquires on your behalf with Hamble props. Cost of machining taper and keyway £80>£100 or whole half coupling complete £180>£200. Hamble prop phone number is 01489574222. Dave's your man. Jim

Thanks again for your valuable help. I've asked a few local companies for quotes. It'll be interesting to see what they have to say. In the meantime I'm taking out the cutless bearing - which is another epic job!

 

[boatmike]

Before you get drastic and start cutting things in half I have had this problem before. If there is room by far the easiest option is to remove the bolts on the engine mounts where they are attached to the bearers and move the engine forward. If you mark the positions before doing so and don't mess with the vertical adjustment sliding it all back afterwards should be easy and alignment not difficult to re-instate. Jam the prop to the ground with a suitable length of wood and get a long wrench on a socket to remove the nut. Put an extractor in the flange and if it wont budge use a blowlamp but shield the GRP from heat with something first.

 

[Mei Mac]

Before you get drastic and start cutting things in half I have had this problem before. If there is room by far the easiest option is to remove the bolts on the engine mounts where they are attached to the bearers and move the engine forward. If you mark the positions before doing so and don't mess with the vertical adjustment sliding it all back afterwards should be easy and alignment not difficult to re-instate.

Hi. That's a very good idea but I have very limited room and can't move the engine back since the water intake filter is tight against the wooden bulkhead (aft to the filter) that separates the engine compartment from the under deck space that is home to the shaft, coupling and so on.

There's always a snag isn't there?! But there's a great saying in Welsh that I like: "Yn nhrofeydd y ffordd mae ei phrydferthwch" - that is, "The beauty of the road is in its twists and turns".

I'll get around this turn sooner or later!

 

[Mei Mac]

HI. An update.

I asked Hamble Props for a quote but they never got back to me. I contacted Clements Engineering
http://www.clementsengineering.co.uk who produced this beauty for me for £160.

So problem solved. Thanks for all your advice/ideas etc.

 

[jim.howes]

I am pleased you managed to get what you needed and at what I think a reasonable price, but I am very disappointed with the lack of response from Hamble props. The quality of there products is first class but would appear there PR is lacking the same quality. Jim