I'm trying to find a locknut for the spindle arm on my55 F-100.
IT'S 7/8 fine tread but I've tried 7/8 -14 but it's not the same.
Any help is appreciated.

 

The parts book shows it to be 7/8-14, if it's a F-100 (Model "C" below)

 

ROSS,
Thanks for the reply,
I thought I was lucky to find a7/8 -14 nut in a hardware store today.
But it was exceptionally hard to tread on.
I have a castle nut that treads by hand, but no hole for a cotter pin.
Possibly a bad batch of nuts.

 

Drill a hole.

 

If it's a lock nut, it's supposed to be hard to install (hence the 'lock' moniker). If not, it would benefit from running a thread chaser (not a tap) through it. New hardware these days is notorious for having sloppy threads and being hard to put together.

 

Tried that, the drill bit broke in the hole.
Can't get it out.

 

Wayne.It was hard to tread with an impact gun,long before it hit the plastic lock.
But ill try the tread chaser.Thanks

 

Are you sure there isn't already a hole, possibly with the remains of a broken-off cotter pin in it? The parts illustration shows a cotter pin and washer, and it is described as a castle nut, which is only used with a cotter pin

 

Probably what your are dealing with is the heavy handed mechanic that put it in originally hit it so hard he compressed the threaded portion which expanded it.

Can you get a thread chasing die on it? That would restore the proper diameter.

Leave the broken drill bit in there but grind off any part of the bit that extends into the threads. When you assemble it, use an self locking nut and red locktite.

 

Thanks everyone for your help.
I am going to try to find a tread chaser7/8-14.
I'am sure that wil lwork. Nick

 

Curious indeed......I would think it originally had a castle nut/cotter pin. If you want to go lock nut,,,,,does the store have any more nuts that size.....maybe ya grabbed a bad one.

 

If you use a chaser be sure to go slowly and use plenty of cutting oil. For each full turn of the chaser back off 1/2 a turn to break off the chip that forms on the leading edge of the chaser. Then advance another full turn. This is a procedure that you cannot hurry. Take your time and your threads will be as good as new.