I had to get splined lug nuts for my wheels. Picked up on eBay. I think these are the same ones, though I got chrome: https://www.ebay.com/itm/20-Black-12x1-25-Spline-Lug-Nuts-Key-for-Subaru-Nissan-BRZ-FR-S-STI-BAJA/253111950908

I can’t use the tapered lug nuts unless I machine my wheels. Stuck with mag lug nuts otherwise.


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Double post app glitch.

 Post a pic of the wheels. Back in the day the aluminum wheels often didn't use tapered lug nuts. The slotted U.S. aluminum wheels that were on my 71 used a straight lug nut that fits into a hole in the wheel.

In other news...
 
Inspiration:

 
Progress:























 
Finished:


 
Now I need to refinish my center caps.

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73128?  The fit in the bore of the wheel will be very tight.  I've had to massage mine with a round file to get them  back in.  Probably overtightened them.  You need the washer also.

Looks like OReilly also carries a Dorman lug nut.  They show the size as correct for a 240Z.  SAE/metric hybrid.  You could go down and buy a single one just to check.  Pretty sure that's the size.

https://www.oreillyauto.com/shop/b/tire---wheel-16779/lug-nuts-and-studs-25062/wheel-lug-nut-12670/835b5ec42d53/1973/nissan/240z?prodAttr_10648=M12-1.25&prodAttr_10633=Mag

Edited January 11, 20196 yr by Zed Head

Yeah, I think I’m going to have to open up the lug holes on the wheels somehow. This is the closest thing.


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 Dug out one of my previously mentioned U.S. wheels. The holes measure 5/8" and have no taper at the top, just the indent for the washer. What is the hole size on your Shelby's and is there any taper at the top of the hole? 

4 hours ago, Matthew Abate said:

didn’t see anything with a narrow enough shank, but it’s totally possible that I miss-measured the hole diameter.

When I was trying to find lug nuts for my old aluminum wheels, I had a little trouble getting an accurate measurement number for the hole diameter. Seemed the hole diameter as measured at the front face of the wheels was smaller than the hole diameter at the back side. But the holes were never meant to be tapered, so wtf?

Under magnification, the issue became clear... All the years of lug nut tightening by previous owners had extruded the aluminum at the wheel face a little bit and actually squeezed a metal ridge into the lug hole. So when I measured that hole at the front, I was actually measuring the diameter inside that burr. But the diameter at the back side (with no burr) was the accurate measurement.

So I'll second Zed Head's mention of a round file. On mine, some quick work with a fine round file to remove the burr and my lug choice went up dramatically. Hopefully that's what's going on with yours as it was an easy fix.

 The Cap'n scores again. I checked for a bur on mine, not feeling one I measured 5/8" on the face side. Well just to make sure I just measured the backside. Sure enough, 13/16". No wonder the lugnuts got more difficult to install after twenty years. 

9 minutes ago, Mark Maras said:

No wonder the lugnuts got more difficult to install after twenty years. 

Haha! Yup. Metal smeared into the hole. I don't remember how much difference I found between front and back on mine, but a sixteenth sure sounds like a lot.

And there's no way there is supposed to be taper in those holes. They were drilled after the casting was done and sized for different applications. Those holes should be the same diameter thru (plus/minus drill wander, etc).

Anyway, hopefully that's what Matthew is dealing with as well.

10 minutes ago, Captain Obvious said:

Haha! Yup. Metal smeared into the hole. I don't remember how much difference I found between front and back on mine, but a sixteenth sure sounds like a lot. Those holes should be the same diameter thru (plus/minus drill wander, etc).

Anyway, hopefully that's what Matthew is dealing with as well.

1

 It probably wasn't a full 1/16". Poor light in the basement, old eyes, etc. I do remember the lug nuts having no taper to them at all. Just a bit of a bevel at the tip to get them started into the wheel. I never thought about filing them out. I just kept putting more anti-seize on them.