What are these NUTS called ?

John Timmins · Feb 3, 2015

I restore Mercury outboards with automatic transmissions - 1957-1962. A guy who worked at Mercury 42 years said Kiekhaefer stormed through the plant one day screaming that his outboards were NOT going to be glued together with Locktite etc. Below are two locking nuts found on Mercury outboards of that era. They are probably on many other Mercury outboards, but I can't say. I only work on these models.

The nut with the rectangular shaped stamp has this shape stamped in 3 of the 6 flats. They are on the power head studs for securing the power head to the drive shaft housing.

The other nut has the ends of 3 flats "pinched". These are on the power head casing bolts which bolt the block and block cover together along the crankshaft centerline.

1. What are these nuts called if I order some NEW ones ?

2. Are these aircraft nuts that are supposed to be used only once ?

I have a crankcase that has some issues with sealing....leaky crankcase. I sealed the crankcase with Locktite 518, but I did not use these locking style nuts. I believe that driving down the road may have loosened my stainless steel nuts and bolts which then out the sealing Locktite 518 - my own fault of course.....

. Tightening up the crankcase nuts and bolts beyond the recommended torque didn't seal my crankcse, so surgery #again# for my 1962 Mercury 25 H.P. Merc 250 Super Hurricane .

Transman304 · Feb 3, 2015

http://products.coburnmyers.com/viewitems/nuts/center-lock-nuts

check out this site. Are these nuts in a place where they can be staked once installed?
Maybe they strike the top of the nut with a special die to mark the top of the nut.

sublimate · Feb 3, 2015

Toplock nuts - distorted thread at one end
Centerlock nuts - distorted thread in the middle

riggs1117 · Feb 3, 2015

castle nuts, but they usually have more groves

John Timmins · Feb 3, 2015

A Mercury factory guy told me they are called Distorted-thread hex locknuts !

Castle Nuts...aren't they Castellated nuts ? Harden them up and pass a cotter pin through the "castles " ?

JRC3 · Feb 3, 2015

riggs1117 said:
castle nuts, but they usually have more groves

Nah. Castle nuts are different and are usually meant to be locked in with a cotter pin. Or they can be called castle nuts because of the wrench used to turn theme.

rlitman · Feb 3, 2015

sublimate said:
Toplock nuts - distorted thread at one end
Centerlock nuts - distorted thread in the middle

This. They work like a nyloc nut. All locking nuts are supposed to be single use... Can they be re-used. Maybe.

riggs1117 said:
castle nuts, but they usually have more groves

Nope. Castellated nuts have a groove. These are just deformed enough to lock onto the threads.

On another note, loctite may not work so well on stainless. There is a special activator for just that purpose.

jgorm · Feb 3, 2015

rlitman said:
This. They work like a nyloc nut. All locking nuts are supposed to be single use... Can they be re-used. Maybe.

I've reused them, but buying new is always smarter!

fsae0607 · Feb 3, 2015

Locking nuts can usually be re-used up to five times. This seems to be industry standard, based on aerospace fastener specs that we use at my work.

In my experience qualifying locking fasteners at my work, five cycles seems to be the minimum. We also make fasteners designed to hold their prevailing torque for up to 250 cycles!

stage20 · Feb 3, 2015

"stover" nuts or sometimes called "all metal " locknuts will work as well.

this type the whole nut is distorted.
use them for high heat applications where nylon will melt.

toplessHO · Feb 3, 2015

in a pinch Ive made my own
center punch to middle while in a vise
chisel to end of nut cut in an X
neither will be as good as the factory ones

LXCam · Feb 4, 2015

It's a distorted thread nut. You can get them at McMasterCarr and depending upon what size and how many you need, I have a pretty damn good selection of SAE stuff. If I have them, your welcome to them.

Also if you have issues like this with other assemblies that the nuts just won't stay tight or if your stud or bolt/nut combo expand so much it causes it to leak, look up Nordloc Lock washes.....that'll solve any problem you'll ever come across.

justme- · Feb 4, 2015

You can get these from any good hardware supplier - a good hardware store with a pick-a-nut section will have them and can get in the sizes you need. Very common on power equipment - in fact we have a bag of about 200 on a shelf in the shop in the most common size we use.

Dennis Leigh Henry · Feb 4, 2015

These are classic lock nuts with physical locking features~distortion. I'll have to see if I can find my old reference book that specs those features out to see what the industry calls them. They do have standards around them for manufacturing, retentive torque, etc. When I worked at Gunite I was responsible for supplier quality and I went to many nut manufacturers including several that made the lock nuts for drum/hub, drum/spoke wheel, rotor/hub, rotor/spoke wheel fastening.

Dennis

GYPSY400 · Feb 4, 2015

Looks to me like an old style "stover" or "prevailing torque" locknut. The current design of said nut looks slightly different as the top of the nut is slightly round and the hole is ovaled on one end making it impossible to install upside down. If your not concerned about looks, they can be found at any hardware store.

http://www.reglover.com/desktop/reg/productsView.php?order_number=00000AA1301001881

Dennis Leigh Henry · Feb 4, 2015

GYPSY400

Prevailing torque.. that's it.. that circuit in my brain just send some electricity back thru it...

OP: Check this out...

http://www.macleanfoggcs.com/products/prevailing-torque-nuts/

I know this is for larger nuts, but it is the "what" behind "what is it".....

Wikipedia had this: http://en.wikipedia.org/wiki/Locknut

Dennis

LS6 Tommy · Feb 4, 2015

riggs1117 said:
castle nuts, but they usually have more groves

Nope. Castellated nuts are not lock nuts. they are used with cotter pins, like on front wheel bearings. The OP has Deformed Thread nuts. Snapper used them on lots of stuff...

Tommy

ihrescue · Feb 4, 2015

sublimate said:
Toplock nuts - distorted thread at one end
Centerlock nuts - distorted thread in the middle

Sublimate got, but are those specific thread distorted nuts needed, or would some other locking means including Loc-tite as good?

Here's a link to McMaster-Carr distorted Nut page http://www.mcmaster.com/#hex-locknuts/=vrhd8p

rlitman · Feb 4, 2015

ihrescue said:
Sublimate got, but are those specific thread distorted nuts needed, or would some other locking means including Loc-tite as good?

As said above, distorted thread nuts still work at high temperature. Nyloc (and at higher temperatures Loc-tite) fail when hot.

Dennis Leigh Henry · Feb 6, 2015

rlitman said:
As said above, distorted thread nuts still work at high temperature. Nyloc (and at higher temperatures Loc-tite) fail when hot.

As If I'm not mistaken, the mechanical locking feature will allow multiple (I'm remembering 5 from my days in QC), whereas Nylock, Locktite are one and done.....

Dennis

Dennis Leigh Henry · Feb 6, 2015

LS6 Tommy said:
Nope. Castellated nuts are not lock nuts. they are used with cotter pins, like on front wheel bearings. The OP has Deformed Thread nuts. Snapper used them on lots of stuff...

Tommy

Yes Tommy, classic is the cotter pin style.

In aero (and other safety critical industries) .. they are also used with lock wire.. Photo shows some recommendations from http://byrongliding.com/technical/lockwiring/

Dennis

BeachBoy · Feb 6, 2015

LXCam said:
Also if you have issues like this with other assemblies that the nuts just won't stay tight or if your stud or bolt/nut combo expand so much it causes it to leak, look up Nordloc Lock washes.....that'll solve any problem you'll ever come across.

We use a LOT of Nordloc at work (large hydro turbines/generator), and they are perfect, but $$$

Dennis Leigh Henry · Feb 6, 2015

BeachBoy said:
We use a LOT of Nordloc at work (large hydro turbines/generator), and they are perfect, but $$$

http://www.nord-lock.com/

LXCam · Feb 6, 2015

BeachBoy said:
We use a LOT of Nordloc at work (large hydro turbines/generator), and they are perfect, but $$$

I can only imagine what they cost for larrge ones. I'll only need 10mm and smaller for my needs and they ain't cheap.

Modern Jess · Feb 6, 2015

BeachBoy said:
We use a LOT of Nordloc at work (large hydro turbines/generator), and they are perfect, but $$$

I'll second this. Nordloc ended up solving a difficult problem I was having with the exhaust header on one of my scooters (the racing bike, natch). Nothing else worked, and the nuts kept backing off. NyLocs obviously won't work on an exhaust header. Nordloc did the trick.

Zrexxer · Feb 6, 2015

OK, now that the original question's been answered a dozen times (not all of which were correct!) let's see some pictures of these old outboards you work on. I love the styling of the motors from that era.

RonB001 · Mar 8, 2015

Sublimate pointed to:
Centerlock nuts - distorted thread in the middle

ihrescue drilled down to:
McMaster-Carr distorted Nut page http://www.mcmaster.com/#hex-locknuts/=vrhd8p

One level deeper gets to:
Distorted thread locknuts, centerlock
www.mcmaster.com/#hex-locknuts/=w82df0

What are these NUTS called ?

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