Radius arm thread

[Alastair]

I know this was covered on the old forum but with no search facility I'll revive it. Can someone tell me what thread is used on the axle end if the radius arm?
Thanks
Alastair

[Ruairidh Dunford]

It is the same as the halfshaft Alastair - 5/8 special thread 16 tpi.

[Alastair]

Thanks Ruairidh - I knew you'd know! I'm trying to clean up some butchered threads but couldn't find the right die. That explains it. I'll see if Mr E Bay can provide one...
Alastair

[Ruairidh Dunford]

You would be very lucky to get one on eBay, the last one I bought was from Tracy Tools but they don't appear to stock them any more.

I have a recollection that David Cochrane was selling them at one point as well.

[Reckless Rat]

If you get stuck, try Riley's Machine tools in Sheffield. Their address is 657-661 Attercliffe Road, Sheffield S9 3RE - tel 0114 243 4703.

[Alastair]

There is one on ebay but its from China... Tracy Tools was my next port of call and they do a 5/8" X 16 TPI W/FORM, which I assume means the thread is Whitworth form, so I'll try that.
Thanks for the info about Rileys, Reckless.

Alastair

---

Quick update in case anyone is misled - the die from Tracy Tools is not the right one. Ruairidh has just rung me to say the Whitworth form is wrong and that the thread is one of the Admiralty patterns on which Sir Herbert was so keen.
I'll see if Rileys can help.
Alastair

[Ruairidh Dunford]

Actually I am not so sure that the Whitworth form is incorrect Alastair, standard threads for 5/8" BSF is 14tpi - the special Admiralty threads are 16tpi - so on second thoughts you may have found the correct one.

5/8" 16tpi is correct. Somebody else will be able to confirm but I do remember that in the past new halfshaft nuts were being sold that were a very tight fit and it turned out they had been cut incorrectly so do get some confirmation on this before proceeding

[David Cochrane]

You would be very lucky to get one on eBay, the last one I bought was from Tracy Tools but they don't appear to stock them any more.

I have a recollection that David Cochrane was selling them at one point as well.

Yes, your recollection is correct! I still sell them - see BT967d here

[Ruairidh Dunford]

Good to see my memory is not all gone to pot David - can you answer the question about Whitworth form for me please?

[Stuart Giles]

Actually I am not so sure that the Whitworth form is incorrect Alastair, standard threads for 5/8" BSF is 14tpi - the special Admiralty threads are 16tpi - so on second thoughts you may have found the correct one.

5/8" 16tpi is correct.  Somebody else will be able to confirm but I do remember that in the past new halfshaft nuts were being sold that were a very tight fit and it turned out they had been cut incorrectly so do get some confirmation on this before proceeding

Halfshafts are 5/8 x 16 TPI Whitworth Form sometimes called Whitworth Fine; anyway, the thread angle is 55 degrees -AFAIK so are pretty well all British threads except Cycle (60 degrees) and BA (47.5 degrees  IIRC). The Admiralty threads are effectively the same as Whitworth Form. Admiralty threads get a mention here.
http://www.gerardsgarage.com/supportfile...Tables.pdf

There's comprehensive information regarding a vast variety of thread systems on this site.

http://www.gewinde-normen.de/en/index.html


BTW, some while ago, I bought  some of those halfshaft nuts mentioned by Ruairidh which wouldn't screw onto a halfshaft; was difficult to know if they were slightly undersize, or whether they had been made with a 5/8 x 16 UNS thread  anyway, I used a 5/8" x 16 WF tap on them; it removed a fair bit of metal, but the nuts did fit the halfshafts afterwards.