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MG Midget and Sprite Technical - Nuts - Swivel Pin

I know bolts come in different strengths or grades (2, 5 and 8) and are identified by the markings on the head of the bolt. Do nuts come in different grades as well? And if so how are they identified?

The nuts in question are the ones that go on top of the swivel pins on the front suspension/steering assembly. They are 7/16 x 20 castle nuts and they have a single circular groove or marking on the top. Can I use a run of the mill hardware store castle nut or is this a special grade?

Thanks,
Paul
Paul Noeth

hardly anyone uses castle nuts any more, and I believe new kingpins do not have the hole drilled to take the split pin but are supplied with a suitable nyloc nut. So unless you have old kingpins and are a purist, I'd look for nyloc.
David (davidDOTsmithAT stonesDOTcom)

The kingpins are new and they do have the cotter-pin hole. They were purchased a few years ago from Moss (USA) and I'm now just getting around to putting it all back together.

I was wondering if nylocs would do, but did not know if there was a grade or hardness issue to be concerned with. Apparently not. There doesn't seem to be much stress on the nut itself as it just supports the wheel and suspension components when they are unloaded. But it is a part that seems critical to safety and I did not understand the marking on the old nut.

Does a nyloc affect the torque spec for tightening?

I am not a purist by any means, but the castle nuts just seem so... uh... old school classic brit. I'd expect to see a lot of them on a WWII Supermarine Spitfire. Surely a machine that has a lot in common with my MKII midget.
Paul Noeth

Yes, nuts can come in grades just as bolts do but as far as I know there's no markings on them to distinguish the various types. As far as castle nuts, I've found only one grade listed in the McMaster Carr catalog and they carry about everything in fasteners. If you can find castle nuts in grades go for it. Otherwise you're limited to whatever you can find.
Bill Young

This thread was discussed between 12/11/2009 and 13/11/2009

MG Midget and Sprite Technical index

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