Early frame bracket bolts and nuts

[Original Smith]

I've been working with a friend on 1914 frame bracket to firewall bolts. First, the bolts seem to be a type of step bolt, possibly of Fords design. The head diameter of these bolts appear to be 7/8-15/16 diameter about 1 1/2" long. That head size seems a little large, but checking a known unrestored 13 verifies this. Next, the 5/16 nuts are thick and hex. On my car they are 9/16 hex, thick. I even have some that are 19/32! Could Ford have used them? Trivia I know, but I like that stuff! I see Restoration Supply has the thick hex nuts, so will probably get some. Lang's doesn't have them.

[Adam]

If you’re going to make some, Get the prints from the archives instead of guessing.

[Scott Rosenthal]

I doubt those bolts and nuts were specialty engineered. Ford did not create drawings for common mechanical hardware.

[VowellArt]

Ya know, there is a possibility that he has already checked that source and contrary to the widespread and (very popular) belief that all the mysteries are available in the archives and have every bloody little thing from 1909, 1927 on these cars....they don't! Especially on something so common as a shoulder bolt that was once a commonly stocked item in every hardware store in the land and has since become very uncommon item like some of the screws and bolts that don't exist anymore and you've either got to make them (something that Larry WOULD do) or tap your threads to a larger more common size (something Larry would never do...hell he doesn't even like acorn nuts).

Larry is good at this sort forensic stuff. He did a great job with everything he's ever laid a hand to, remember the tail pipes? Even figured a low cost way around the "electric upset" that the later pipe had for the muffler to fit against, even though it could've been done faster with an open end tube welder....but then that would cost some bucks, and he figured how to do it without that outlay.

[TRDxB2]

Just curious if the nut differences are also related to square or "U" bottomed castellated nuts

[Original Smith]

I understand Restoration Supply has them, but they are too thick?

[DanTreace]

Gail Rodda's T Parts Identification books pictures the 13-14 dash to bracket bolts, gives dimensions as: Step bolt, 5/16" x 18thrd., large head diameter of 13/16". The hex nut used are 5/16" x 18 thrd. and 1/4" (.250') height, with dia. across the flats measure of 1/2" (.500").

Restoration Supply offers a close match to the hex nut, Grade 5, #NUT536, 5/16" x 18thrd. and 19/64" (.296") height with dia. across the flats as 9/16" (.562")