Thread size for 5/8 steering wheel nut

[gregmajor]

Good morning everyone. The threads on my steering column are a little boogered up. I’ve searched for quite a while and can’t arrive at a definitive answer for the threads per inch. It’s a 5/8 and my thread gauge makes it look more like 16 TPI, but that’s a little unusual. I’m wondering if it’s supposed to be 18 TPI.

Anybody know for sure before I try and chase the threads with a die?

 

[Doppleganger]

I know in the 80s it was a fine metric - M14 x 1.5 iirc.

I had a 9/16 x 18 on a 78 Buick column as well.

 

[gregmajor]

This is for my 79 K10. Could be metric, I reckon, but I don’t have metric thread gauges. I’ll look into it. Thank you!

 

[gregmajor]

Following up for anyone that may run into this in the future. There’s almost ZERO information online. Anyway, my 1979 K10 with a non-tilt column has an M14 1.5 thread. I found a die and cleaned it up in just a couple of minutes.

I bought three different nuts. One from GM, one from the hardware store, and one from the AWESOME Outback Truck Parts in Spring Texas. I triple-checked and I’m 100% certain that M14 1.5 is correct for this column.

Doppleganger called it!