Been watching this thread wander all over the place, so I figured I’d throw my offering into the soup. These are just some thoughts on how I view this subject having removed my instrument clusters to replace gauge and clean them.
The thread on the studs of the instrument cluster of my 1950 AD are #10-32, I see no reason why they would use any stud that was larger than that to hold the instrument clusters in place on any of the later units.
Unified American Threads only come in certain sizes.
There is no #14 in the Unified American Thread system
All you have to do is mic the major diameter of the thread to find out what you’ve got.
Thread Size Major Diameters
#8 -------------------- .163”
#10 ------------------- .189”
#12 ------------------- .215”
1/4” ------------------ .246”
An inexpensive thread gauge will tell you your pitch.
If your thread is messed up from a previous owner then chasing it with a die is an easy enough task after you have determined the size and pitch. Dies are available from places like McMaster with a 13/16”od that should allow you to chase the thread on the instrument studs. Most decent Hobby Shops also carry small number size dies also.
Although the “Pal” nuts or “Push” nuts may have been used on the later vehicles to speed production, they are not the best fastener to use. You’re better off just pitching them and using a standard nut as they can damage the screws threads. Brass nuts are a good sub for the original nuts because they are not prone to rust like the steel nuts are. The thumbscrews are a good idea if you plan on removing your instruments often but a hex nut and star washer is the best choice since most people will only need to pull their clusters once or twice, if ever in all the time that they have their trucks.
Here is a quote from a commercial vendor about the use of Pal-Nuts:
“Pal-Nuts are a push-on nut that is reusable and can be used with a threaded or non-threaded stud. Why fiddle with a washer and nut when you can just use a Pal-Nut that has the washer built in? Just push the Pal-Nut on with a socket wrench and move on”
Denny Graham
Sandwich, IL
