Outer steering column thread type and more

[Ian Watson]

Hi all
I have removed the wedged steering column from my special to donate the parts for build of a David Cochrane sport box.

I have 3 columns in pieces on the bench to get the least worn where I don’t have a replacement part. This has meant that some parts had been centre punched to prevent loosening, even with trying to partially drill the punch marks, the threads still require attention. The set screw that locks the outer column in the steering box has munted a few threads as it had not been located in the appropriate slots in the threaded boss. 
So, I am hoping some one will be able to answer some questions on thread types, or point me to a previous post that will help. I have looked in the archive site but not found anything.

1) Outer steering column thread type
    OD - close as to 1-3/4”
    TPI – looks like it might be 22tpi (not entirely convinced)
    What is the real thread type and tpi?

2) Steering box bronze bush and control bracket tube socket
    This sits at the bottom of the steering box. It is 7/8" OD – not able to find TPI with thread gauges, but looks like 12 (in ¼” callipers on 1st and 4th peaks)
    What is the real thread type and tpi

I wanted to firstly know what the threads are and then see if any local car enthusiasts have taps or dies to clean them up

Ian Watson

[Austin in the Shed]

No 1 is from memory 1 3/4 x20

[Martin Baker]

When restoring my Speedy many moons ago, I damaged the thread in the steering box. A toolmaker friend made me a specail tap (huge!) to restore the threads. Happy to lend it to anyone in need.

[Ian Watson]

Happy New Year to you all. Let's hope we can all enjoy a little more motoring freedom from Covid this year.

Thank you both for your replies, very helpful.
I'll do a little more research with 20tpi.

Martin, thank you for the offer. I am in New Zealand so wouldn't be practical, but appreciate the offer.

With regard to the bronze bush, I found a #5 thread cleaning file and the 22 tpi face worked a treat on the thread. The associated nut will need another approach. The centre punches have compressed the thread at that point, so I will try a small pin punch and attempt to tap the thread at these points back in line.
That's my task for today.

Safe motoring

[Ian Watson]

"Austin in the Shed", your memory was good.
Managed to check thread and it is 20tpi as you thought. 1-3/4 OD makes it cycle thread (BSC).

Just ordered 2nd tap and die from Tracy tools. I have an other standard box to repair so they will be of value.

Thank you