Nut / Bolt Specs

DBentley

Member
I've taken several 5/8" X 18 nuts and bolts off an '47 Ford 8N I'm restoring. Some of the bolts need a die run over them to clean up the threads. I took three different nuts I removed to a hardware store that sold 5/8" X 18 Fine thread (Grade 8) hardware and the old nuts will run on the new bolts about two turns and stop. Same result with a tap they had for sale. I know that at least one of the old nuts is good. Have the thread specs changed in 67 years?
 
straight bolt thread coarse or fine should be just that.

either nut is bad.. or the fastener was replaced with something else non standard.
 
Nothing has changed, standard threads go back way
farther than the 40's. And metric bolts would not
have been used on a true American made product!

The nuts can be retapped to remove rust.

The bolts should not be chased with a die! The
threads are rolled on and chasing them with a die
will undersize the threads. Wire brush is your
best solution, or replace them.
 
Wire wheel or buy a thread file at your parts
store. Make sure you use the side stamped "18" and
clean up the threads out close to the end.
 

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