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Shaft Coupling Stuck to Transmission Flange

11K views 30 replies 11 participants last post by  brownoarsman 
#1 ·
I'm in the middle of removing my universal 5411 engine mated to a hurth transmission, and have a pressing (ha-pun!) question before I lose the community dock to the Labor Day weekend. Everything is off the engine - except that the prop shaft and its coupling are still connected to the transmission flange, even though I've removed the four bolts connecting the coupling to the transmission flange. The packing nut is all the way loose and leaking water when I wriggle the engine (the shaft is moving because it's still somehow connected to the transmission), but I can't push the prop shaft coupling and shaft back from the transmission, or move the engine forward with the two still locked together. Knowing that transmissions are surprisingly fragile and unsurprisingly expensive, I don't want to force anything. The eight hours of internet searching all make this seem easy (e.g. remove four bolts, loosen the packing nut, and slide it on back!), with the issues arrising when people need to remove the coupling from the shaft - but this is not my problem. I want to leave the coupling attached to the shaft, but just remove the coupling from the transmission so I can lift the engine to take the head off.

Here is a picture of the coupling and transmission connection, I've removed the four bolts shown in the picture already:


Please let me know if you have any suggestions, and thanks!
 
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#2 · (Edited)
Looks like an old 'drive saver' coupling.. could it be there are bolts on the transmission side too? Also many couplings have 'blind' threaded holes that can be used with bolts to separate the two halves.. maybe have a look for that too.

Also... maybe you're trying to separate the wrong parts??

 
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#4 ·
Yes, but the 'fat' part of your coupling, indeed the coupling itself regardless of type, is not part of the transmission. The gearbox drawings end at the output flange, to which the coupling connects.

I agree your shaft should disengage based on removing the 4 bolts, but I don't think the entire coupling body will. Though it looks a bit different from the one in my posted picture, it still looks like a 2-part drive saver - meant to minimize vibration due to slight misalignment.

I can see nuts on the tranny side of the output flange.. if you can get those off the entire thing could separate from the tranny flange.. allowing you remove the engine/gear.
 
#5 ·
Thanks for the thoughts Faster! It's certainly a weird looking thing and doesn't resemble any of the couplings I've seen on other threads and blogs. Sadly, both faces of the coupling are smooth, so I don't think blind holes exist, and I can't see any other ways of fixing the shaft in place, except for maybe those big screws mounted in rubber that are just barely visible in the above picture on the sides of the coupling. The four bolts shown match up to the transmission diagram in the parts manual (sorry I didn't upload it before - very slow computer).

I thought maybe the shaft was threaded and somehow locked into the transmission, but I can't get the shaft and the transmission to turn independently either.
 
#6 ·
I had a 5411 on my previous boat and my coupling looked nothing like your picture. Mine had the "four arm" coupling at the transmission as shown in the Universal manual. Four bolts would disconnect the shaft coupling from the propeller shaft. Yours looks pretty corroded and I'm sure that's part of the problem.
 
#7 ·
#8 ·
Well done, OB!

This should help the OP quite a bit.
 
#10 ·
Slightly clearer, cleaner drawings:

http://file.seekpart.com/keywordpdf/2010/12/18/2010121843016797.pdf

It does look, now, however, that the entire coupling assembly SHOULD disengage from the tranny's output flange if the 4 bolts are out.. so it's gotta be corrosion holding things up or (thinking externally) if a shaft zinc is too near the strut the prop shaft won't slide out either...

Hope all this helps you out a bit, brownoarsman!
 
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#11 ·
Thanks a lot, everyone! Nice to know there's a flexible coupling on the boat now that I think back to a couple of those crab pots I snagged in Florida sailing down to Key West with the transmission in neutral! :)

I'd rather not remove the shaft from the coupling (and who even knows if I can with the shaft inside the boat if the corrosion is so bad that I can't remove the coupling from the transmission!). I agree - with those four bolts out the coupling should disengage from the trans - the prop shaft has clearance down to the strut to disengage. I'll pull out my thin blade and rubber mallet, and see if some gentle taps might dislodge it. Thanks again everyone, and what a piece of history!

Dan
 
#12 ·
It's probably an inner flange rusted solidly in place. I'd keep soaking it for days in PBBlaster, heat it up a bit, keep tapping it, and keep trying to get it apart gingerly. You are right about the fragile nature of trannys and the cost to fix. With that in mind, it may be a better alternative to just cut the shaft off and haul the engine up where you can effectively get at it. A shaft is a lot cheaper than a new tranny.
 
#13 ·
Thanks everyone for your help! I couldn't get the pry in, but I've wiped the coupling/flange connection with PB Blaster, and will repeat that process for a while. After taking out the engine mount bolts, I've repinned the mounts back into place to accommodate the Labor Day wakes. Luckily my mooring isn't too far from shore :) I've also got a call out to the company (glad they're still around!) to ask for suggestions. Thanks very much for identifying that coupler OB, I never would have figured out what that thing was. Enjoy the weekend everybody!

Dan
 
#17 ·
Thanks for the help everyone! I was wiping the area with PB Blaster on a rag to avoid getting the gasket eater into the transmission. Unfortunately, it's true what they say about being on the water being safer than being on land. Five days on shore in a house, after six plus months of singlehanding around the Bahamas and East Coast, and I wound up in the ER and am now confined to bedrest for over a week.
So, unfortunately, nothing to show for the effort yet, but at least the PBB will have a long time to soak in ...
 
#18 ·
Well, keep us posted and .... details, man, details.. what did you do to yourself???
 
#19 ·
Ha! Well, since you all deserve a laugh after all the help you provided, even if the laugh is at my expense, and since this is an anonymous forum ...

As my username might imply, I rowed in college, and while I wasn't particularly good, I still rowed a lot, and managed to row my way into a long-term overuse injury. Part of the physical therapy for this injury is to fix an elastic tube to an anchor point, step back so that your hands are about two feet in front of you and the band is tensioned, and swing your arms straight back so that each hand is outside its corresponding hip.

I've been doing this PT for years, and on the boat I used my mast or similarly rugged attachment - in fact, everything is either backed with aluminum plate or large fender washers. But before my little single-handing adventure, I used doorknobs for years. Doorknobs in my home, doorknobs in hotels, doorknobs in my office. I've also installed tens of doorknobs working construction and just general DIY as a kid. Every doorknob I've ever installed or worked on has the handle as an integral piece of the mechanism: through-bolted or screwed to the other side of the mechanism, or a part of a monocoque structure. Most online guides to elastic tube therapy exercises suggest using a doorknob as an anchor point. You can probably see where this is going ...

My parents recently moved into a new house, and I have my boat on the mooring ball out front - it was very convenient! Well, I began doing my PT exercise as I always do, this time in the house, and just as soon as the tube, which is a very thick elastic tube, reached full extension, the doorknob sprang off the door and hurtled into the singular place most apt to cause men pain. After about twenty minutes on the floor, I managed to pick myself up, look at the doorknob, and realise that these ones are press-fit onto the locking mechanism, much like a prop shaft and coupling, actually! Never seen this before.

Anyways, after one hour when the pain didn't disappear and I now had a large lemon in my pants, we drove to the ER. While I may not have been able to dodge a doorknob, I did manage to dodge a bullet, luckily, and avoided surgery and have only minor tissue damage. I figure if Lance can win all those tours with only one testicle, I'll probably do okay with 1.9!

Should have stayed on the boat!
 
#22 ·
That's the problem with production knobs. They just don't build 'em like they used to. 'Better give the jewels a rest for a while . How about a thin SS strap ,(about 4 inches wide)U shaped with eye ring on one leg. Open door, slip over edge, close door.most doors have enough clearance. Be sure the door opens away or the lacerations could be severe when someone comes thru.
 
#23 ·
I know I'm coming in a bit late here but I've attached a couple of photos of the coupler you have that might help visualize what you are dealing with. Mine is attached to the Hurth transmission on my 5416 engine.

As you can see on the transmission side there is a kind of cross arrangement that the bolts pass through. on the blue coupler you can see a circular lip, that engages the inside of the "pads" on the end of the cross arms. That is a pretty tight fit if I remember right, even without it being rusted solid. I think I just used a thin metal wedge tapped in between the flange and each of the cross piece arms to separate them.

Don't use heat on this coupler unless you are prepared to replace it. The big bolts on the outside pass through rubber bushes that will be ruined by heating.

HTH
Eric
 

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#24 ·
Good info Eric.. I suspect you've nailed the issue. Once the oarsman isn't walking bowlegged that should help him out.. the power of the wedge may well be the trick.

Oarsman.. I'm happy to say I don't 'feel your pain'... but you have my sympathies and thanks for sharing.. ;)
 
#27 ·
Thanks for the tips and humor! They certainly brought a smile. I'm well on the road to recovery, and should be able to get back on the boat after another week or two.

Eric - those pics are super helpful, and, though your arrangement is much cleaner, looks like mine! Do the cross arms grip that coupler lip at all? Or do they just sort of rest on it. Back when I was in the laz working on it, I tried putting my thin pry (actually, a thin steel putty knife) in between the coupler and the flange arm and giving the pry some light taps, but couldn't get the wedge into the seam - I assume because of the corrosion. Did you have a similar experience? Just wondering what you meant by the lip engaging the cross arms of the flange. Thanks!
 
#30 ·
Oarsman,

Great to hear you are on the mend, and thanks for sharing your adventure with the doorknob. It took me while to get off the floor when I read it, before trying to give a serious answer to your engine problem. Glad you could see the humor in spite of the pain ?

To your questions, the inside lip on each of the four cross arms has been machined to match the outside of the circular lip on the coupler. It's a tight fit. On the photo of the coupler you can see the shiny spots where the cross arms meet the coupler face and lip.

I have a very thin wedge that is about 5 inches long, 1 1/2 inches wide and tapers from about 3/8 inch down to almost zero. It's made of hardened steel, my old journeyman gave me it when I was an apprentice about 30 years ago. He called it a "fox wedge", and it has saved my bacon on a few occasions over the years. So it's much thinner than a screwdriver tip, and the taper is very gradual. It would be easy to make one with a bit of steel bar and a bench grinder. I tapped it in to each of the 4 meeting points in turn, a little at a time. I soaked them in PB Blaster beforehand.


Get well soon
Eric
 
#31 ·
Success!

Thanks for all the help throughout this process, everyone. A couple of weeks ago, after months of applying penetrating oil, the prop shaft slid free with a gentle tap from a 'fox wedge' :). Yesterday, I painted the bottom and had some extra time to lift the engine out!

The water jackets in the manifold are visibly split - though I think this might have been the result of trying to free the epoxied-in manifold bolts with a blowtorch, as I inspected the business end of the manifold pretty closely with bright lights back in April as I cut gaskets to fit it and applied RTV to it, and it was fine then. The corrosion between the head and the block is strong enough to hold the engine entirely suspended without any supporting bolts (I put the remaining bolts in with a half-inch gap as insurance in case the head and block did separate).

To get her out, I levered the front up with a chain hoist and a chain between the two front mounts, slid some two by fours under, and then it was an easy job of hauling her forward (while keeping the rear mounts on the tracks) until I could pull her out all the way with the hoist. The wood beam I had the hoist connected to slid easily along the companionway top, so I could easily reposition the engine on to the railroad ties I had set out.

Next - lifting the engine into my truck with the main halyard, fixing the shaft in place, and splashing! Thanks again for all the help in preserving the shaft while getting rid of the engine!
 

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