What size nut is this?

[KyleR]

This may be a silly question, but I'd like a second opinion before I go purchasing the wrong tool. I'll be changing both Tides shaft seal kits (the whole assembly) during our upcoming haulout and am getting parts and tools gathered now. They are original to the boat (2002) and are in poor condition overall.

Based on the attached drawings, it looks like the nut (Item 7) that holds the coupler on the shaft is a 2 1/4" nut, but I just want to make sure I'm reading it correctly. If you look at all the other items, they use the "inch marks" with the dimensions, but not on this part for some reason.

I've also heard that it is a nyloc nut and requires a thin-wall socket to fit inside the coupler. I wasn't sure what all the nomenclature for "CSL 2-1/4 SHT" meant.

Has anyone done this job and/or have any other advice? Thanks in advance!

[Viper]

CSL is a self clinching nut. Not sure about SHT but I suspect it may be a metallurgy standard/term.

Yes it will be a nyloc type nut and you will need a thin walled socket for it. In a pinch when I couldn't find the right thinned walled socket, I've taken a regular one and had a prop shop turn it to the right thickness. I've grinded them down myself too. Some prop shops will also carry these sockets but a good tool supplier shouldn't have an issue getting one for you. BTW, I've also had to grind down a thin walled socket, so don't be surprised if that's what you run into.

[bud37]

If that turns out to be a short nyloc, I would consider replacing it with a new one to be sure the locking is still good. I am sure many would just reuse, but it has been on there for years etc.

For what its worth, I have ground down sockets many times with a bench grinder, especially plug sockets, they are hard so don't overheat them while doing it.....good luck with your project.

[km1125]

Source of the post CSL is a self clinching nut. Not sure about SHT but I suspect it may be a metallurgy standard/term.
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I thought CSL was for a castellated nut, which would make sense if it has that cotter pin that the parts list shows.

But I wouldn't bet the farm on that being right either.

[Viper]

It could be in this case km, I didn't notice the cotter pin. Don't see many setups like that. They're a pain.

[KyleR]

Thanks for all the comments! Best forum ever

[Hugo]

I’ve had that coupler apart. I have a 444 couple years newer then your 396 and it was not a nylon lock but a castle nut with a cotter pin. You I’ll see the cotter pin on the coupler now if it uses same style as mine. The nut was 2” and I had to weld it to a big hunk of steel I could hit with a small sledge hammer. Also had to make a tool that bolts onto the coupler bolts to block the coupler. It was a very difficult job to get it apart. I could not get the nut off with a 3/4” bar and a pipe over it that was about 5’ long. It’s either going to be easy or not fun. Good luck.

[KyleR]

I could not get the nut off with a 3/4” bar and a pipe over it that was about 5’ long.

Yikes! Here's a pic of the cotter pin location. Does this look like the same configuration? Also, did yours have a 2" shaft? Do you happen to have any pics of your setup? Thanks for taking the time to reply!

[bud37]

If they have used some kind of thread locker you may have to use heat.....then again it might just pop off !!

I guess it will all depend on whether the couplings have been worked on since new boat delivery and who has done what since.

[km1125]

There shouldn't need to be a lot of torque on that nut. It just needs to be tight enough to pull the shaft fully into the taper. The castle nut and cotter pin then make sure it can't back off at all.

But... seeing the corrosion on the outside of the coupling, who knows what you might run into trying to get the old one off.