!933 355C Question

[packrat]

Can anyone tell me the thread size of the "projector" on the horn actuator. I realized that I am missing the plates that it screws into so I am making them. The thread is only about 3/8" long and measures 1.241" dia. There are 5 threads in 1/4 " so I assume it is a 1 1/4-20 thread which is not standard National Fine (NF) but does exist. I was able to find a tap and made a part but it will only go on a turn and a half before it binds. It acts like the pitch is wrong. Could this possibly be Metric?

[packrat]

After more careful measurement I have concluded that this is a 31MM x 1.5MM pitch thread and with good old Ebay a tap is on the way from China. Couldn't find a US one. I remember when working on some of my old Caterpillar stuff that metric threads would show their ugly head occasionally. I never dreamed that Cadillac used some. I'm still learning. I will report back if this is correct.

[packrat]

FYI the thread is 1 1/4 - 18. I finally remembered I had a Starrett thread gage. Duh!