Cummins Marine Diesel Repower Specialists › Forums › Marine Transmissions › Coupler shaft nut

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  • July 11, 2023 at 9:04 pm #151447

    Kyle Routh
    Participant
    Vessel Name: Verity
    Engines: Twin 5.9 6BTA 370 HP
    Location: On the move!
    Country: USA

    My 20 year old Tides shaft seals are leaking so I am replacing them.  Probably sticking with Tides although I’ve read all the very compelling arguments around packing glands.  Anyways…. I just want to verify that the shaft nut that holds the coupler on is removed in a counter-clockwise manner when looking at the nut from the end of the shaft, as in the photo. I’ve put a LOT of torque on that nut and I’m getting no movement.  I’m using a 2″ socket that I ground down to make it thin-walled so it would fit.  And yes, the cotter pin has been removed and I verified there are no set screws. I started wondering if maybe this nut was reverse-threaded and I was trying to turn it the wrong way.  Any help is greatly appreciated! Kyle

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  • July 14, 2023 at 1:27 pm #151590

    Kyle Routh
    Participant
    Vessel Name: Verity
    Engines: Twin 5.9 6BTA 370 HP
    Location: On the move!
    Country: USA

    Update:  I was able to get both coupler nuts off.  I did give clockwise a try, but got nothing.  So I went back to counter-clockwise (normal thread) and a bigger cheater bar.  While applying a lot of torque and tapping the socket with a hammer they both broke free!!  Now to get those couplers off!! 

    Thanks again for the suggestions!

    July 13, 2023 at 8:57 am #151522

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    Just because I have never seen it on that end of a shaft does not mean that it could not be a LH thread.. Before I’d cut, I think I would try the “other way”.

    July 12, 2023 at 6:41 pm #151489

    Clark Leighs
    Participant

    I don’t have your coupling system  but maybe try the other way.

    I got caught years ago trying to get my shaft nut off.      It is L.H. threaded but i could not see that.    After fighting it for an hour   I just figured what the hay and went the other way and it released.

    1 user thanked author for this post.
    Kyle Routh
    July 12, 2023 at 12:05 pm #151478

    Kyle Routh
    Participant
    Vessel Name: Verity
    Engines: Twin 5.9 6BTA 370 HP
    Location: On the move!
    Country: USA

    I did heat it with a propane torch to no avail.  Also while it was hot and I was pulling on the cheater bar, I repeatedly hit the socket on the sides pretty hard to try to break it loose.  Nothing.   Not looking forward to cutting the shaft but it’s not looking good.

    Thanks for your reply – just glad to know that I’m not actually tightening it!

    July 12, 2023 at 10:01 am #151475

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    I personally have never seen one with a LH thread.. Set screws yes. Because it is a brass nut, it will expand quickly compared to the shaft — Consider heat?

    1 user thanked author for this post.
    Kyle Routh
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