How to get prop shaft coupling off .. Help!

Hi, was just there doing that. The inside diameter of my coupler is too small for the shaft, plus it was rusted onto the shaft. I now have water seeping through the boat around the stuffing box housing and this has just got to be from all the hammering trying to get the coupler off, then back on. Don't hammer on it.

It really does look like you don't have enough room for a puller, I've posted a picture of my puller so you can see how much room it required. (The sail tie is so things would not fall into the bilge when it came off.) For scale, it is four inches (10 cm) between bolts, and the shaft is 1-3/8" (3.5 cm). I had a choice of two sizes for pullers, this is the larger one - the smaller one would not have fit around the coupler.

Before I bought the puller I spent half a day trying to remove the coupler with four long bolts and lots of washers. The first picture shows how it is when you start. You'll need something really strong, smaller than the diameter of your shaft - I used a large socket (that belonged to someone else /forums/images/graemlins/grin.gif , but it survived without a mark). Of course I had to take the four bolts back off to get the socket nested inside the coupler. /forums/images/graemlins/mad.gif (The tape is holding on the key so it doesn't fall into the bilge.) (The bilge is five feet deep /forums/images/graemlins/shocked.gif )

Center the socket as best you can on the end of the shaft, put in the four bolts, and start tightening the nuts. When the shaft won't turn any more, pull out the bolts, add two washers, and go at it again. It'll exercise your tools, your arms, your lower back, your patience, and your vocabulary. But it works. In the second picture you can see the band of rust on the prop shaft, between the tape and coupler for all those washers I had added. You can also see the shiny socket between the coupler halves.

The coupler was so darn tight and rusted that it took almost as long to finish getting it off with the puller as the first half did with the bolts - but it was MUCH easier. Even if you don't think a puller will fit, at least go to the store and measure one to confirm this before messing with the bolts - I wish I had ... live and learn. /forums/images/graemlins/tongue.gif

Hope this helps.

Priscilla

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Faced with this problem on my aged Trapper, I jacked up the engine, Removed the prop, slid the entire shaft out forwards under the engine, bearing in mind that once the prop end has cleared the cutlass bearing the shaft becomes very manoueverable. Did the stern gland in the comfort of the house, then reassembled the whole thing Lock stock and barrel back under the engine. Good Luck!
 
Thank you all .. and very helpful pictures Priscilla
Puller or nut under pressure .. which produces the biggest force? 4 bolts pressing on a nut or a socket ought to, but presumably the thread on the puller is less steep to improve the mechanical advantage (?)
Where do I get a suitable puller?
 
I bought a puller from Halfords, they come unassembled and can be used 2 or 3 legged. It looks just like the one in the picture. Measure the length of coupling before you buy it because the legs come in different lengths,
 
The four bolts will give a far greater and more easily managed force. The problem with pullers is that they have several hinged joints, which makes accuracy difficult to maintain, and it can be difficult to prevent the end of the screwed driver from wandering over the end of the shaft.

I would suggest that if you can't shift it with four bolts and a big nut then a puller won't even look at it. It can be quite surprising how tightly a taper will lock up if the nut has been tightened enthusiastically. Make absolutely certain that there is nothing else holding it, a tapered pin or something else, then put some force into your coupling bolts, or, as suggested above, some alternative ones. If you can get some heat treated ones (black) from a car parts outlet they will give a much higher force without fracture.

Don't go at it too much with a hammer. Ultimately all the shock load is being taken by the gearbox output bearing, a rolling element type usually, which should never be hammered.
 
The gearbox bearing would only be involved if the output flange was being used as a component of the puller. With an independent puller (or even take the flange off the gearbox and use it as suggested, but not connected to the gearbox) then some judicious whacks should shock the taper apart.
It's difficult to explain, but hammering hell for leather won't have much effect. It's a matter of building up the forces in the components with a puller, and then using an accurate and sharp blow to effect the release.
It's like drifting bearings out of housings. It's not how hard, but where you hit that counts.
 
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...then some judicious whacks should shock the taper apart.


[/ QUOTE ]
I remove my prop by tapping the sides. Once the puller is in place I hold the head of a large hammer against one side of the boss and tap the other side with a smaller hammer. Never fails.

If you have to resort to a blowtorch pieces of plasterboard make an excellent heat shield.
 
Asked the same question last month on here.

Had exactly the same problems, Hit it, heated it, you name it the coupling did not shift.
Finaly followed the reverse screwing advice (also suggested by Alan) by inserting a socket between the shaft end and the coupling, had to use 'allthread; in the end due to access, took a few hours as had to reset it a few times but yes this method does work.
My coupling was fixed in addition to the keyway by 'Two' grub screws which also was a problem to remove, left overnight after spraying with WD40 and then sprayed WD40 down the grub screw holes to help release the shaft/coupling.
All of the above takes time but as Alan says no damage, all I have to do now is put it all back on again!
Good Luck
Mike
 
I agree with you, std flange etc, if a nut there then its a tapered shaft with a key. Do as you say and thats it, perhaps a tap on the end of the plate will hasten things.
Stu
 
Lakey
they are getting confused, as far as I can see hes trying to get the flange off the prop shaft, Im a big fan of logically applied brute force, as you say a few taps in the right place distorts things fractionally for a short (milliseconds) time so that the taper grip fails and the whole shooting match comes apart, reminds me of Mini front suspension ball joint pins, [--word removed--] to separate BUT two hammers together and they would give up the ghost and come apart dead easy.
Stu
 
heat seems to have been discounted early in this thread, I think that with pressure applied with a socket and then a cloth wrapped round flannge and boiling water poured over same a suprising amount of heat will be transferred to the flange and a light tap might just be enough /forums/images/graemlins/wink.gif
 
Absolutely. Newtons (something) Law. Think of the Newton's Cradle.

It sort of "springs" the grip.

Shouldn't need a whole lot of hammering. Something's gone wrong if that's what you're having to do.
 
I fully agree, and am not averse to the odd, carefully applied bang with one or two hammers. That's not the same as hitting the flange hard in the axial direction which was being suggested by another poster. Rolling element bearings are very easily damaged by impact.
 
Done it !!!!
1. I had a puller made from 6 mm mild steel plate with 4 holes to match those on the coupling ( £10)
2. Used puller to press on an under-size socket spanner
3. managed to force the socket over the end of the prop shaft without having any effect on the coupling
4. spent 2 hours trying to get the socket off
5. eventually fitted an old screwdriver bit through the middle of the jammed socket .. to press on the prop shaft .. and tightened down the bolts on my steel plate puller
6. heated the coupling with heat gun
7. Hit end of coupling with large hammer
Bingo !!! off it came (jammed socket and all)

There is a spline on the shaft that sit in a groove on the coupling .. nothing else

Thank you all for all your help. I ended up using all your suggestions

Peter /forums/images/graemlins/smile.gif
 
Very useful post. I'm fighting with a volvo coupling that has a tapered pin. How do you get the thing out? I tried a hammer. Verified it wasn't an allen key or screwdriver. Flushed it with WD-40. I tried brute force with a 5 ton gear puller..... was hoping to just shear it. No dice.

There has to be a trick to this short of drilling it out. Ideas greatly appreciated.

On a related topic, what are the odds that the driveshaft will be 1 inch instead of 25 mm? The boat is a Tartan 27 and the engine was a Volvo MD6A. Originally the boat had a Atomic 4 and a 1 inch shaft. While I do have a micrometer I'm not confident that I can read 25 mm vs 25.2 mm (1 inch vs 25 mm) on it. Especially not while on all 4's crawled back in my engine space.

I'd like to avoid replacing the shaft, but Volvo uses a LH prop and the Kubota going in will require a RH prop. I'm guessing that shafts may be specific to direction of rotation....
 
Did this very job this weekend for first time.

The gearbox flange looks identical to your but mine is probably a bit bigger (75HP engine).

I was surprised how firmly the flange was on the shaft & came to conclusion hitting it was a waste of time. I located the woodruff key and tried tapping it inwards in case it was on a taper and jamming but still no joy.

I finally used a pulley extractor (hooked legs) and once under enough pressure (the point at which I decided it was never going to come off) I again tapped the flange with a hammer and it spung off with a loud bang. In reserve I intended trying a hub extractor (takes up less room) but that would have involved using the flange bolts with washers.

If you remove the shaft rubber water seal and slide shaft out as far as it would go you would have room for a pulley extractor.

Good Luck.
 
My engine is out, so I have plenty of room for an extractor. My problem is that their is a tapered-pin holding the flange on. I can't figure out how to get the pin out.
 
I have to replace my shaft so when the dealer said they'd take it out for me as a goodwill gesture I said I bet you have to saw the shaft off. Guess what they did and it took me 45 mins with coupling in a vice to undo the nut and extract the remains of the shaft using a 3 legged puller, a blowlamp and hammer.

I will be replacing the shaft with a non tapered one and a new split coupling so I can get it all apart in the future.
 
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