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 Urgent Request - Track Rod Dies		  Forum Locked  Topic Locked
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KevinA

New Zealand
671 Posts
Posted - 31/03/2019 :  23:56:50  Show Profile
Bruce's photo shows sharp crests which is indicative of a 60 degree profile
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Bruce Sutherland

United Kingdom
1564 Posts
Posted - 01/04/2019 :  12:01:48  Show Profile
Kevin,
On closer examination of my drag link threads, they have rounded crests, but still to a BSC profile:




Bruce. (PB0564)
Edited by - Bruce Sutherland on 01/04/2019 13:18:14
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Bruce Sutherland

United Kingdom
1564 Posts
Posted - 01/04/2019 :  17:41:50  Show Profile
Rich,
An alternative supplier to try: https://www.tap-die.com/contents/en-uk/p732_5-8x20_dies.html

Bruce. (PB0564)
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saltandvinegar

United Kingdom
105 Posts
Posted - 05/04/2019 :  14:04:08  Show Profile
The correct threads are 20 t.p.i. on 5/8" Whit Form. (55 degrees)
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Bruce Sutherland

United Kingdom
1564 Posts
Posted - 05/04/2019 :  22:34:18  Show Profile
quote:
Originally posted by saltandvinegar

The correct threads are 20 t.p.i. on 5/8" Whit Form. (55 degrees)


Mike, Jamie,
What is your evidence that the track-rod/drag-link thread form is 55 deg?

60 deg x 5/8" OD x 20 TPI is more recognised thread form than Whitworth 55 deg at 5/8" OD x 20TPI ............... ?????

Please explain.

Bruce. (PB0564)
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Hamish McNinch

United Kingdom
110 Posts
Posted - 05/04/2019 :  23:01:19  Show Profile
‘More recognised’? By who? And why is that relevant?
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Bruce Sutherland

United Kingdom
1564 Posts
Posted - 06/04/2019 :  01:44:26  Show Profile
quote:
Originally posted by Hamish McNinch

‘More recognised’? By who? And why is that relevant?


By me! and the British Standards Institution

Checks for ALL thread data show the only 5/8" OD thread with 20 TPI to be one of the two STANDARD variants of British Standard Cycle/Cycle Engineering Institute (BSC/CEI) with 5/8" OD thread have either 26 TPI or 20 TPI AND all BSC/CEI threads have 60 deg thread flank included angles - Q.E.D.!!!!!

Bruce. (PB0564)
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Jon Pedoe

United Kingdom
56 Posts
Posted - 07/04/2019 :  19:16:22  Show Profile
Mine is the same as Bruce's and I believe they are the original parts on my car, jon PB0373
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NeilF

United Kingdom
66 Posts
Posted - 08/04/2019 :  15:13:37  Show Profile
The photo above and Bruce's earlier similar photo both show a thread gauge marked 20G1/4". I do not understand these markings - G1/4" is the ISO 228 identification for 1/4" BSP parallel thread which is 55 degrees Whitworth form and 19 TPI. I have no explanation for the 20 before the G but it could be just the identification number for the gauge.
Powerplus also offered a G3/8" right hand tap, this is also 55 degrees and 19 TPI - this can all be confirmed with a quick internet search.
In my 50+ years of working in mechanical engineering I have never encountered a cycle thread anywhere except on my Raleigh bicycle.
It is not uncommon for engineers to create special threads based on standard thread types when the standard is unsuitable. American unified threads acknowledge this need and publish standards for UNS (special), UNEF (extra fine) and constant pitch UN threads.
There seems to be a general consensus that the thread is 5/8" x 20 TPI and my expectations based on the age of our cars is that it would be 55 degrees Whitworth form as noted by S & V who by coincidence manufacture replacement track rod ends for our cars.
Neil
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Foz

United Kingdom
769 Posts
Posted - 08/04/2019 :  15:43:40  Show Profile
Manufacturers are noted for protecting their"investment in their product" by using "non standard" sizes. Mr FFord being noted for a few thou up or down..... means more trouble to pirate their parts so more likely to use their branded part.(Genuine Factory Part....) As the thread in question joins two items + locknut which are a factory product there is no requirement to use a "standard" thread.... unlike the nuts and bolts to join components together ... which could be damaged or lost in the local garage and would need replacing easily and quickly.( and cheaply....).
FOZ
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Oz34

United Kingdom
2539 Posts
Posted - 08/04/2019 :  18:38:23  Show Profile
I know little or nothing about these thread forms however, my track rod and drag link are from S&V as are my track rod ends. I am however using original lock nuts which work beautifully. This suggests to a simple soul like me that Mike knows what thread MG used and I would be happy to take his word for it.

Dave
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coracle

United Kingdom
1937 Posts
Posted - 08/04/2019 :  20:07:45  Show Profile
Apologies in advance: There is no doubt that it is certainly a very long thread.
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Bruce Sutherland

United Kingdom
1564 Posts
Posted - 08/04/2019 :  20:20:48  Show Profile
quote:
Originally posted by coracle

Apologies in advance: There is no doubt that it is certainly a very long thread.

Bitter and twisted too!

Bruce. (PB0564)
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rustcollector

United Kingdom
410 Posts
Posted - 08/04/2019 :  22:01:32  Show Profile
Cycle thread were used on bsa And matchless motorcycles and possibly others.
Quite a while ago I was trying to work out these threads. I can’t remember what I came up with as I put it on the back burner thinking I would get back to it later. I do remember l found another possible thread to be admiltry . I may get back on to this in a couple of days and can comment more and add to further confusion.
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rustcollector

United Kingdom
410 Posts
Posted - 08/04/2019 :  22:06:09  Show Profile
Just occurred to me that if using Mike’s track rod ends then make links to suit. Only when using original track rod end would you need more research. What is really needed is one of the magnifying devices( can’t remember the name) then you can accurately measure thread angles etc.
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