Prop nut size?

Discussion in 'Diesel Engines/Drives/Transmissions/Props' started by dtfeld, Apr 15, 2018.

  1. dtfeld

    dtfeld Member GOLD Sponsor

    134
    Jun 5, 2016
    Atlanta
    410 Sundancer 2001
    Cat 3126 V-Drives
    Planning for the move north to Atlanta. I will have to reinstall the props. Planning in advance to have the tools and proper parts on hand.

    Sea Ray Parts Manual for the 2001 410 with diesel option shows 1.25" Hex Jam Nuts.

    Can anyone confirm this is the correct size nut?

    Also...what wrenches do you use/recommend? Do I need a persuader bar? I'm 200lbs + and with a 18"-24" arm, that's a lot or torque.

    Nut.PNG
     
    Last edited: Apr 16, 2018
  2. my3sons

    my3sons Well-Known Member SILVER Sponsor

    Feb 24, 2009
    Upstate NY (lake Erie)
    2004 400DB, Onan 9 kw Gen, Highfield RIB,
    Cummins 6CTA
    I can not confirm, maybe someone else will, but will offer this. My prop shaft diameter is 1.75" and uses the 1.25-7 nuts.
    My friends 2001 410 express cruiser with cummins power has 2" shafts and uses 1.5"-6 nuts
    Do you know your prop shaft diameter?
     
  3. dtfeld

    dtfeld Member GOLD Sponsor

    134
    Jun 5, 2016
    Atlanta
    410 Sundancer 2001
    Cat 3126 V-Drives
    Never measured it but everything I find indicates 2" shafts. I have CATs so there could be a difference. I'll probably have a couple sockets on hand and keep the correct one.

    Still need to determine that...
     
  4. my3sons

    my3sons Well-Known Member SILVER Sponsor

    Feb 24, 2009
    Upstate NY (lake Erie)
    2004 400DB, Onan 9 kw Gen, Highfield RIB,
    Cummins 6CTA
    Sorry, You were looking for wrench sizes not thread dimensions? Thought you were looking to buy prop nuts.
    I just use large adjustable wrenches. This is a place where the cheap pittsburg Harbor freight wrenches are fine, they don't get a lot of use. 24"ers will work. They can also be used on motor mount nuts and other large fasteners on the boat.
    If you have not installed props before, research it. it's not rocket science, but it's not slap on the props and tighten them down either. Good luck.
     
    Last edited: Apr 16, 2018
  5. dtfeld

    dtfeld Member GOLD Sponsor

    134
    Jun 5, 2016
    Atlanta
    410 Sundancer 2001
    Cat 3126 V-Drives
    Mark. That is correct, I am looking for the wrench size. I'm thinking these are going to be 2-1/4" Hex.

    I have looked at it, and I have a game plan. My basic understanding...

    1. Install without key, mark where they bottom out, mark the location on the shaft.
    2. Install with Key, make sure they are all the way on the shaft, adjust/trim key as necessary
    3. Torque nuts on, small on first, then large one.
    4. Cotter pin in place.

    I think there's a detailed write up on here somewhere...
     
  6. barros57

    barros57 Member

    33
    May 19, 2015
    Lake Minnetonka, MN
    350 Sundancer 1991 "Sunny Daze"
    268 Sundancer 1987 "Offshore Drilling"
    454 7.4L Mercruiser Bluewater Inboard, Hurth V Drives
    350 5.7L Mercruiser 260/V8
    The correct process is to use lapping compound to "grind" the tapers of the prop and shaft to match without the key installed. Use blue layout fluid to check the fit. This tapered fit is what actually holds the prop. The keyway is just a failsafe.
     
  7. dtfeld

    dtfeld Member GOLD Sponsor

    134
    Jun 5, 2016
    Atlanta
    410 Sundancer 2001
    Cat 3126 V-Drives

    Is that require for reinstallation? Never seen or read about that process.
     
  8. my3sons

    my3sons Well-Known Member SILVER Sponsor

    Feb 24, 2009
    Upstate NY (lake Erie)
    2004 400DB, Onan 9 kw Gen, Highfield RIB,
    Cummins 6CTA
    It depends. I do it. Some care a little less about the finer details.
    The first time takes longer because there's more lapping to do. If you don't know if it was done previous, It's recommended for sure. But consider that there are a lot of props replaced everyday by divers not lapping prop to shaft fit.
     
    Last edited: Apr 17, 2018
  9. ZZ13

    ZZ13 Well-Known Member GOLD Sponsor

    Nov 25, 2009
    Lady's Island, SC
    2001 400 Sedan Bridge
    Cummins 450 Diamond
    My props have been off and on 5 times in the past 4 years. Twice by divers and three times by boat yards. They take off the nuts, pull them off, push them back on, reinstall the nuts. Never been lapped. This is the first I've heard of that process so now I'll ask around my boatyard about it.
     
  10. quality time

    quality time Well-Known Member

    Oct 30, 2007
    Upper Chesapeake Bay
    2003 480DB and Kencraft 190 CC
    QSM11's
    I lap mine and will be doing them this weekend. Probably once is good enough unless something changes like new props or shafts are installed.
     
  11. barros57

    barros57 Member

    33
    May 19, 2015
    Lake Minnetonka, MN
    350 Sundancer 1991 "Sunny Daze"
    268 Sundancer 1987 "Offshore Drilling"
    454 7.4L Mercruiser Bluewater Inboard, Hurth V Drives
    350 5.7L Mercruiser 260/V8
    Here is a good video of the process if you are interested.
     
  12. Woody

    Woody Well-Known Member PLATINUM Sponsor

    Nov 20, 2007
    N. Wisconsin/Lk Superior
    2005 420DA
    Cummins 6CTA8.3
    IMHO, it's not necessary for re-installation...just make sure shaft and prop hub bore are clean. When I send my props out for tune up it often looks like they run something through the bore to 'clean it up' so I'm in the habit of lapping the re-conditioned props the first time they're installed.
     
  13. dtfeld

    dtfeld Member GOLD Sponsor

    134
    Jun 5, 2016
    Atlanta
    410 Sundancer 2001
    Cat 3126 V-Drives
    I watched that video, good info. I doubt the local yard is going to that much trouble. I'm doing it myself, so we'll have to see once I get the props back.

    For this year, I'm going to have the props cleaned, but they were in pretty good shape, so just planning to reinstall. Once I get the boat setup the way we intend to use it, I'm planning to make adjustments and realignments next haul out.
     
  14. dtfeld

    dtfeld Member GOLD Sponsor

    134
    Jun 5, 2016
    Atlanta
    410 Sundancer 2001
    Cat 3126 V-Drives
    I'm planning on a 2-1/4" nut size...anybody have a pic of their wrench for this job?
     
  15. quality time

    quality time Well-Known Member

    Oct 30, 2007
    Upper Chesapeake Bay
    2003 480DB and Kencraft 190 CC
    QSM11's
    I use a 24" long adjustable.
     
  16. dtfeld

    dtfeld Member GOLD Sponsor

    134
    Jun 5, 2016
    Atlanta
    410 Sundancer 2001
    Cat 3126 V-Drives
  17. Woody

    Woody Well-Known Member PLATINUM Sponsor

    Nov 20, 2007
    N. Wisconsin/Lk Superior
    2005 420DA
    Cummins 6CTA8.3
    I just went out to the shop and measured my new spare prop nuts. I know that these are identical to the original prop nuts. I have 2" shafts, the nut measures 2-5/16". Remember you should hold the inner nut when tightening the outer nut.
     
    dtfeld likes this.
  18. quality time

    quality time Well-Known Member

    Oct 30, 2007
    Upper Chesapeake Bay
    2003 480DB and Kencraft 190 CC
    QSM11's
  19. dtfeld

    dtfeld Member GOLD Sponsor

    134
    Jun 5, 2016
    Atlanta
    410 Sundancer 2001
    Cat 3126 V-Drives
    Wrench 2.PNG wrench1.PNG Wrench 3.PNG These are the cheap options...
     
  20. dtfeld

    dtfeld Member GOLD Sponsor

    134
    Jun 5, 2016
    Atlanta
    410 Sundancer 2001
    Cat 3126 V-Drives
    Thanks for the measurement Woody.
     

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