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making your own torsion bars

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  • making your own torsion bars

    Anyone know how to heat treat torsion bars? A quick look at racing TB suppliers seems to indicate that 4340 is used by them...anyone have any ideas?

  • #2
    I've never heard of 4340 used for springs before. Seems like it would crack very easily under repeated flexing. Torsion bars are just springs used in a different application. You should treat the metal requirement the same as you would a spring.

    "Spring steels. These usually contain 0.6-0.9 % carbon together with similar quantities of manganese to provide appropriate hardenability (US specs. 1065, 1085). About 0.35% silicon is also included to resist 'sag'. About 1% Vanadium is also included in some specifications and small additions of chromium and /or molybdenum may also be made. (US specs. 6150, 8660, 9260)."


    • #3
      A few years ago I was building some lawn furniture for my wife using flat bar stock similar to a car leaf spring to give a springy/cushioned feel to the chairs. In the course of my research for a cheap source of the material I checked with a local automotive spring shop.

      I found that different material is used for leaf springs than is used for coil springs. There was a logical reason for the difference in material choice which I can't remember now.

      I ended up with flat bar "plow" steel, hot rolled 1045, and it worked well.

      Anyway, I assume a torsion bar would use similar material to a coil spring. How about checking with an auto spring shop for some advice? Maybe they could even source material for you.


      • #4
        I think Chrysler used 5140 for torsion bars for many years.
        Heat treating a torsion bar in a Home workshop is next to impossible unless you have a long furnace, instrumentation a lots of experience.
        The setup costs will far exceed the cost of purchased bars.
        Check later post below.

        [This message has been edited by Ted Coffey (edited 06-12-2005).]

        [This message has been edited by Ted Coffey (edited 06-12-2005).]


        • #5
          Just refreshed my memory by checking my notebook. Torsion Bars and Coil springs used in autos used to be 5160 not 5140. There may be some newer alloy in use today.