Need Help Locating Castle Nut

Last fall, when I winterized my boat. I noticed a little bit of grease seeping around the inner seal on one of my hubs. I opened the front and confirmed there was water contamination in the grease. Also I noticed my castle nut was showing signs of rust, where the grease wasn't touching...

I bought Tie-Down's Vortex hub that's filled with Lucas Marine grease. Well, when I installed them, I guess I didn't smear the grease on all the open surface. The grease is very tacky and stays put. I noticed a little bit of water condensation on the exposed metal. There was no grease that splattered on the inside of the cap at all. Not what I was expecting. Also, hub was less than 1 years old. But I saw a little bit of grass or something wrapped around my spindle. So I guess that may have damaged the seal. I checked the other side and it looked perfect. No issues at all.

I waited until now to replace my hub. I also ordered what I thought was the correct castle nut to replace my rusting one too. Turns out, it's not quite right.

In the picture, the one on the left is my original castle nut. The right is what I bought. I thought it was 3/4" ID. I didn't realize how thick the new one was until I had them side by side. Anyways, I tried putting on the new one and it went on really tight. Was almost afraid of tightening it thinking I might be doing damage to the threads on the spindle. I had to use my spanner wrench to tighten the nut on. Turns out, the nut is too thick. The slot doesn't reach my cotter pin slot. My hub is locked down before I get to it.

The way my boat is stored, I can't leave it on jackstands, so I had to put back in the old rusting nut. I wanted to take it home and get it measured or take it to the shop.

Instead, I just have the wrong part to take around. It measures .649" thick. Using a ruler tape, the original is ~3/8" thick. I'm not 100% sure of the inner diameter either. To me, it looked like 3/4", but for some reason, the fit was terrible with the 3/4" castle nut I bought. All I can seem to find online is .64" thick nuts, for 3/4" ID. So maybe it's not 3/4", but just a hair bigger?

Ideas? I took the wrong nut around to 1 NAPA and 2 boat shops. All said they don't have such a thing. 1 told me they might be able to special order it in. Another told me to check at a local trailer shop not too far away, unfortunately, they are closed for the day.

I can't believe I'm having this much trouble over a ~$1 castle nut.

Re: Need Help Locating Castle Nut

There are places on the net to order those castle nuts, but like you said, you are not sure of the diameter of the spindle. I have a really light weight trailer and it has 1" spindles on it. I have never seen a 3/4" spindle shaft but that doesn't mean they don't exist. I just haven't seen any. So remeasure the spindle shaft diameter again to make sure it is what you first read. And then you could measure the thread count pretty close as well. Take a 1" ruler and count the number of turns in that 1" length. It should come out to something standard for that diameter. A trailer shop OR an old boat graveyard could be a source for that castle nut. JMHO!

Re: Need Help Locating Castle Nut

just use the old nut... a little surface rust can easily be cleaned off and won't hurt anything

Re: Need Help Locating Castle Nut

smokeonthewater said:

just use the old nut... a little surface rust can easily be cleaned off and won't hurt anything

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Ayuh,.... Agreed,.... There's absolutely Nothin' wrong with the original,.... Nothin'....

Re: Need Help Locating Castle Nut

gm280 said:

There are places on the net to order those castle nuts, but like you said, you are not sure of the diameter of the spindle. I have a really light weight trailer and it has 1" spindles on it. I have never seen a 3/4" spindle shaft but that doesn't mean they don't exist. I just haven't seen any. So remeasure the spindle shaft diameter again to make sure it is what you first read. And then you could measure the thread count pretty close as well. Take a 1" ruler and count the number of turns in that 1" length. It should come out to something standard for that diameter. A trailer shop OR an old boat graveyard could be a source for that castle nut. JMHO!

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See, that's the thing. When I first noticed the rust last fall. I didn't measure the spindle. But I looked online and I saw mainly 1" nuts/washers for sale from vendors. I have 1-1/16" bearings. I figure 1" would be right on. So I bought several sets to keep on hand. 1" is way too big.

Just got back from a local trailer shop. They don't have what I need, but they got something else. Basicly a 3/4" nut with a cage. Not exactly what I wanted, but will work fine for a backup I guess. I do wonder where my original ones come from.

Re: Need Help Locating Castle Nut

3/4 too small. 1" too big.

Are you sure you are not looking for a 7/8-14 Spindle nut?

Re: Need Help Locating Castle Nut

UncleWillie said:

3/4 too small. 1" too big.

Are you sure you are not looking for a 7/8-14 Spindle nut?

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Looking at the video. I already know that nut is too thick. I don't see the dimensions on the website though.

But I believe I might have found the correct nut. I happened to look at Fastnels. They have the standard "Slotted Hex Nut" or castle nuts. And in the sub options, they have "Slot Jam Nuts". It appears to be the same thing, but thinner. I believe this is what I need. So I ordered both the 3/4"-16 and 7/8"-14 slot jam nut. Those are the only thread count for those sizes in the slot version. Do they have a 3/4"-10 but only in the regular thickness.

I also am using new 3/4" washers and those fit perfectly. Also an exact match from the original one I pulled from the spindle. That's another reason I believe the spindle ends are suppose to be 3/4".