Steering side tube

[martyn nutlandParticipant @martynnutland79495]

Hello Everyone

I want to make a steering side tube (drag link if you're American) for a vintage Austin Seven. Could someone tell me the grade of steel tube that would be safe for this purpose?

I know….look for an old one on the 'net'. But living permanently in France, as Brexit cometh, this is an increasingly unattractive option as I strive towards engineering self-sufficiency!

Thanks in advance and if it's not premature – seasons(?) greetings.

Martyn

[martyn nutlandParticipant @martynnutland79495]

What steel?

[Maurice TaylorParticipant @mauricetaylor82093]

Hi, Try to find a drag link from an old Land Rover or similar 4 x 4 and make one from that.

Maurice

[old martParticipant @oldmart]

If ends are to be brazed into the tube, then chrome moly tubing like Reynolds 531 would be best. The molybdenum in the alloy prevents cracking caused by the heat of brazing.

[ChrisBParticipant @chrisb35596]

I would use seamless tube for something like that, chrome moly as mentioned or BS4T45 – both seamless and used for roll cages etc. T45 can be welded and will not require heat treatment post welding.

[StueeeeParticipant @stueeee]

I have cut and welded A7 draglinks before; they are made of quite a thick wall tube and don't appear to be anything fancy in way of material.

If you're going to use the factory "cup and cap" style ball joints you'll want to use 3/4" OD tube which will need to be at least 14SWG wall so that you can machine the 5/8" bore for the inner cup whilst leaving a seating at the rear end.

If you're stuck with metric sizes in France, you could use thick wall 20mm OD tube and skim the outer down to 3/4" at the ends to accept the outer cap and bore the inner ends to 5/8" for the cups.

[martyn nutlandParticipant @martynnutland79495]

Many thanks all – that's exactly what I wanted to know. There's no brazing or welding involved but it's useful to be reminded that there needs to be enough wall thickness to create the correct I/D but, very importantly, leave enough metal for the seating that takes the pad, shims and spring behind the ball connection on the drop arm and steering lever respectively.

Thank you again. Best. Martyn.

[Charles PParticipant @charlesp60333]

I looked at making one but Tony Betts sells the whole thing, tube, cups, end caps and ball joints brand new for £75. It made the sourcing of a short length of the correct seamless tube uneconomic

c

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