Technical Where can you buy 5/16 x 20 nuts

Has anybody found a place for these hard to find nuts that my builder lost for my 51 Dodge? Google says some stupid metric will fit but Google is wrong.

 

Try a gunsmith; they use a lot of weird threads...

Wouldn't it just be easier to swap to standard 5/16-24 bolts?

 

www.McMaster.com

 

Have you tried a M8 x 1.25? 1" = 25.4 mm. 25.4/1.25=20.32 threads per inch.

 

All McMaster-Carr has is the standard sizes....

 

I don't recall ever hearing of a 5/16-20 thread. But.... a look at Amazon came up with a tap and die set for $18. You could make your own if it absolutely necessary to have 5/16-20 nuts. I did not find any sources that sell the nuts but I'll bet there is someplace that has them.

I'm only able to find 5/16-18 and 5/16-24 at the places that sell fasteners. I tried Fastenal, ARP and Graingers.

 

They ain't cheap, but here ya go:
https://www.classicandexotic.com/store/p-513-516-20-nut.aspx

 

I would replace the bolts but they are actually a welded in stud on the bottom of my seat assembly. Just pisses me off that this was taken off and the nuts tossed. Thanks Sporty45. I tried the 8x1.25 and just don't want to mess up the threads if this ever needs taken off, they are under the seat upside down.

 

That's a great site just bookmarked it!

 

Cheap if you only need one

 

Now these ain’t cheap, https://www.classicandexotic.com/store/p-4588-bugatti-type-57-distributor-cap.aspx

 

Where in general are you located?

Charlie Stephens

 

Looks like the builder is going to be paying $3.50 a pop to get a nut.....

 

I am in Windber, Pa 60 miles east of Pittsburgh

 

Thanks for the location. I checked a well stocked local hardware and they had 5/16 18 and 5/16 24. Any chance you have the size wrong?

Charlie Stephens

 

I have never even heard of 5/16-20??

 

I tried 5/16 x 18 and 5/16 x 24 and they do not work. It seems that 5/26 x 20 was used years ago on some Mopars

 

You can look on eBay, there's a few but it looks to be around the same price as the first link.

 

If that metric size is close, run a metric tap on the bolts and call it good. The course standard would also probably do it also

 

That would be a "die".

 

Spillane....where exactly are these bolts/nuts being used?..........andyd.

 

Mr Google came up with these..
20-UN - Unified Extra Fine Thread, which is used for special purposes.
The flank angle is 60°.
Nominal Diameter 5/16" - 20-UN
Major Diameter Inch 0.3125
Major Diameter mm 7.9380
Tapping Drill Size mm 6.700
TPI 20
Pitch mm 1.270

 

Try a The Plymouth Club. Someone there should have some, or at least a source for them.

 

i got a misc drawer full of nuts and bolts from a guy who rebuilt linotype printing machines. i was very excited, they are all cool old high head bolts, nickle plated acorns, odd thickness nut etc, interesting box of junk. however, many of it is not common thread when it gets to real world use. so, its another box of junk

 

Any chance they used an older brit seat and it is a whitworth thread as opposed to sae or metric?

 

I don't recall all the details, but I got stuck a couple of years back with what sounds similar to your dilemma.
I ended finding them on eBay from England.
It seems some of the odd threads are associated with British motor bikes and even before that bicycles.
Some sort of old British Standard ..... something.
Mine were used on Triumph motor bikes as it turned out.
Search wider and you will find them possibly armed with what I have just told you...

 

Or 5/16x18

Sent from my SM-G965U using The H.A.M.B. mobile app

 

Whitworth is the bolt/thread you are thinking of. My '64 triumph was bolted together that way.

 

Tap https://www.victornet.com/detail/TAST-5/16-20.html

Die https://www.victornet.com/detail/RD-5/16-20-B.html