Repairing a Steering column thread

[Beno]

So I’ve hit a bit of a snag and would like some suggestions.

Went to put the nut on the steering column for steering wheel and it turns out the thread is buggered. I had a troll through the forum for other posts and it appears the rather unique thread is 5/8 x 28 TPI (threads per inch).

Has anyone had to re- thread a steering column before? If so how easy/hard is it to find a die set for it.

[Steam]

How bad is the thread and is it just rhe start or the whole thread.
I have in the pst used a small needle file to tidy it up enough to start the nut, then gently and slowly use the nut to reprofile.
The work is done with the file.
Or there are thread files that can be bought.

[Beno]

Yeah I’ve tried the file technique and had someone else give me a hand with that as well  but unfortunately no joy

[Terry]

Hi,

I did a quick search on Google and the first entry that comes up https://www.tracytools.com/index.php?route=product/product&keyword=28%20tpi&category_id=0&product_id=1114 has a die you could use but it is in the UK.

Now by pure coincidence I was looking for a special tap and die last month and the only place I could find it was this same company and although they sent it the same day I paid for it, it still hasn't arrived likely due to the Covid stuffing things up so before I say order one from them I will wait until my new toys actually arrive first.

The other thing with damaged threads can be getting the die to align properly with the good part of the thread while it is trying to start in the damaged area. Now by another coincidence I saw this strange thing on a counter in an engineering supplies shop last week and the staff member explained that is was used to align a die or nut with the good part of a thread. The one I saw wasn't big enough for the steering column but maybe there is something larger in the range if I could remember the brand or name of the thing I saw.

Terry

[moemoke]

probably easier to get another column or you may be able to get a new thread cut by
someone with a lathe, it would probably need to be a slightly smaller thread diameter.

[Beno]

Cheers Terry. I know what you mean about the extra “COVID” delivery time it’s very frustrating. I don’t think I can wait that long as I was really keen to get it over to the vehicle compliance place next week in an attempt to licence it but this has really thrown my timeline out.
And thanks moemoke, definitely worth considering given the alternative.

Don’t suppose if anyone knows the thread pitch do they? I keep getting asked if it’s UNF or UNEF?

[Terry]

Hi,

I did a bit of searching and I think the thread pitch is most likely to be whitworth form, https://www.tracytools.com/index.php?route=product/product&keyword=28%20tpi&category_id=0&product_id=1114

This is based on what I had to order for some other areas of the Moke which are 5/8 16tpi whitworth form.

The UNx form is very similar but starts to bind up as you get further down the thread. BSW/Whithworth is 55 degree cut while UN is 60 degree.

I have updated my link from yesterday to replace the UNS with the BSWS/whitworth.

Terry

[Beno]

So I just got off the phone to a guy at Capital Cutting Tools in Victoria who says the thread is quite common for steering columns and is 5/8 X 28 tpi UN.

He doesn’t have one in stock but can make one but would take about 2-3 weeks to arrive at my door.

[Steam]

Something did not seem right to me with this so I have been out to the shed to check and measure.
Here is what I found.

The socket needed to undo the nut is 33mm or 1 5/16in
the thread has a TPI of 28.
the overall outside Diameter is 17.25mm or 0.679in which is closer to 11/16 than 5/8
the internal measurement of the nut is 16.64mm or 0.655in.

You would be wise to check with the people who are making / offering a die that it measures to these figures.
5/8 threads in any form, Un or whit/british have an overall outside Diameter of 0.625 which is smaller than the ID of the nut.
 Hate for you to pay for something that is wrong.

[Beno]

Thanks heaps for the info Dave.
I can’t believe how this one little thread is turning out to be a big problem with so much different info out there!

[moemoke]

Just doing a bit of googling and found this page
https://www.efunda.com/designstandards/screws/unified.cfm?start=148&finish=227

It looks like it has the pitch data for 5/8-28 tpi UN, scroll down a bit.

[Beno]

Oh wow, my head hurts after trying to decipher the pitch for this bloody thing 

So after reading that I got back a quote to make up a die nut to suit (not with this latest pitch info) and they want $275 bucks to make one! and it will take about 3 weeks to get here..... I think I’ll go back to my beer and ponder a bit more

[Drakman]

Hi Beno,

7ent have MK4? inner steering shafts listed i guess for minis for $99 and the nut $10.  Does a mini shaft work?

https://www.7ent.com/categories/steering/steering-column-rack-and-arms.html

[Mission]

Beno

There is another way and much cheaper.  Thread files are notoriously hard to use properly by hand, if your thread has not been stripped badly take the steering shaft out and take it to a machine shop or some one you know with a lathe. When put in a lathe it will run true and in reverse (with a short thread start at the bottom and work out) at dead slow, the thread file will do the same as the die nut. I seen this done with great success.
 A machine shop can also use a threading cutting tip to clean the thread out no matter the thread pitch - just a matter of setting the feed ratio.

Good luck

[Beno]

Thanks Mission  I think it’s sounding like the better option thus far. It’s just extra frustrating as I just got all of the steering column and attachments back in and the thought of taking it apart again is not appealing but will no doubt have to be done