This nut is nuts

[Steve Jelf]

This afternoon I set about stabilizing a wandering rear fender. I wanted to remove the fender clamp and chase the threads. I had a devil of a time trying to get a socket on the nut. Eventually I got the nut off with a loose-fitting ¾" open end wrench. The clamps have a ⅜-16 thread, and I found that this nut did too. But an ¹¹⁄₁₆" socket was too small to fit it and a ¾" was loose. I don't have a ²³⁄₃₂" wrench, but apparently I should. Is this weird nut a correct Ford original. If so, what possible reason could there be to use such an odd size? Why wouldn't ⅝" or ¹¹⁄₁₆" be good enough?

[Humblej]

I have noticed some odd ball size heads now and again too, often a metric size wrench or socket will fit it better.

[Rich Eagle]

Often the old wrenches fit those original bolts when modern wrenches don't.

[John kuehn]

I do remember the same thing on my cars and especially my 24 Coupe. I finally found a wrench but it was loose fitting and I rounder off a nut a bit. I’m trying to remember if I could get to it with a crescent wrench. But if I did I’m thinking I would have used a 8”;crescent wrench. I did use some good originals on my 21 Touring since I didn’t have any that came with the car. I do remember that.
It could be because the nuts don’t have high sides that cause a socket not to catch good.I
think they are sloped.and don’t have a sharp straight side like other nuts.

[Allan]

That particular nut is well oversized, when compared with a modern replacement with the same thread, just as the 6 nuts are on the wooden wheel bolts. I imagine over the past 100 years, rust and sandblasting by road grit have reduced the physical size of the original nut. I have found that backing one side of the nut and hammering on the opposite side, will loosen it enough to get it off with an adjustable wrench.

Allan from down under.

[Pep C Strebeck]

I would guess, Ford Original. I have been looking for a 3-Z-686 Body Bracket Connecting Bolt Wrench (also numbers 5-Z-212 and 5-Z-212-1) and a 5-Z-212-2 Body Bolt Connecting Bolt Wrench for some time. The 3-Z-686 was/is a 23/32" open end wrench and the 5-Z-212-2 is a 21/32" open end wrench, both original Ford 3-Z or 5-Z tools.

[John kuehn]

Thanks Pep for sizes for the nut.
Those sizes aren’t real common. I don’t recall seeing the 21/32 wrench lately. Seems like I have an older Craftsman that size but don’t know if they are put in the newer sets??
It makes me wonder if those sizes were original to Ford or if they were an industry standard that wasn’t common.

[Art M]

I have many of my father's hand tools, Erich include a lot of 32's sizes. He was a car mechanic from 1924 to 1941. Many are close to metric.

Art Mirtes

[Distagon2]

Steve-

I too have run into those oddball sizes (oddball by today's standards, anyway) and have asked the same question you are asking. I don't know why Ford utilized these particular sizes (23/32"? Really?). Perhaps those sizes were more common in the day, or perhaps cheaper from the suppliers (somehow). Since I am in engineering, it could very well be simply what an engineer specified after doing some "calculations." We all know engineers never think about the poor souls who actually have to work on their creations!

[Mark Gregush]

I have collected some odd-ball size sockets and wrenches. 21/32 is the Model A connecting rod nut size.

[Steve Jelf]

Seems like I have an older Craftsman that size but don’t know if they are put in the newer sets??

I have two, count 'em, two Craftsman #1 combination wrenches — ⁷⁄₁₆" and ¹⁷⁄₃₂". I'm sure they were stuff I picked up at an auction for a few cents. If any such sizes are available today they have to be a special order item. I wouldn't expect to find them in any store.

[kmatt2]

If the 21/32 inch size is the correct size then try a 16 or 17 mm it is about half way between the two. If the 23/32 inch size is correct use 18 mm it is a tad small but close.

[Rich P. Bingham]

Interesting quirk I've been unaware of. If my math is correct, Kevin's suggestion of using an 18mm is a possibility, should be small by about .013". Never thought I'd need a metric wrench on a Model T !!

Thanks for all the information !

[Steve Jelf]

I just tried that ²³⁄₃₂" nut in an 18mm socket. I would call it almost a perfect fit.

[Scott C.]

If I did the math correctly. 21/32" is 18.237 MM. So, that would be just .0093" larger than 18 MM.