Prop nut size?

dtfeld

Water Contrails
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Jun 5, 2016
5,518
Milton, GA
Boat Info
410 Sundancer
2001
12" Axiom and 9" Axiom+ MFD
Engines
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
 
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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?
 
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?

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...
 
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.
 
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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.

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...
 
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.
 
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.


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

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.
 
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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.
 
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.
 
Here is a good video of the process if you are interested.
 
Is that require for reinstallation? Never seen or read about that process.
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.
 
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.
 
I'm planning on a 2-1/4" nut size...anybody have a pic of their wrench for this job?
 
I'm planning on a 2-1/4" nut size...anybody have a pic of their wrench for this job?
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.
 
Wrench 2.PNG
wrench1.PNG
Wrench 3.PNG
These are the cheap options...
 
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.

Thanks for the measurement Woody.
 

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