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Technical Heat treating suspension/steering parts?

Discussion in 'Traditional Hot Rods' started by magnus13, Sep 30, 2019.

  1. magnus13
    Joined: Jun 1, 2013
    Posts: 105

    from California

    I'm modifying the tie rod and forward radius arms on my build to change from traditional rod ends to the early style type. Because I have to go from a female thread to a male thread to accept the new ends, I machined up some threaded adapers that I'll weld in place.

    I had to cut out some of the old material on the tie rod and radius arms and noticed it was pretty easy to cut which made me wonder if it wasn't hardened. Is it necessary to harden any of these parts before or after I weld them in place?

    Thanks! 20190928_163215.jpeg 20190928_154004.jpeg 20190928_201645.jpeg

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  2. Joliet Jake
    Joined: Dec 6, 2007
    Posts: 482

    Joliet Jake
    from Jax, FL

    My experience, no. Besides, "tempering" it IMO would lead to added stress from being harder or brittle in that area. When you welded it you hardened it in that area of the weld.
    quicksilverart46 likes this.
  3. I've never heat treated any of those parts. HRP
  4. pirate
    Joined: Jun 29, 2006
    Posts: 325

    from Alabama

    I doubt the original suspension parts were ever hardened. Most suspension parts are forged from a mild steel and were probably normalized after forging to remove stresses. They were then machined and used. There may be exceptions to this in more modern light weight suspension parts made from tubing.
    quicksilverart46 likes this.
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  5. magnus13
    Joined: Jun 1, 2013
    Posts: 105

    from California

  6. Old HAMB Metallurgist here. Those tie rod end parts are almost certainly not heat treated originally. The only parts that are heat treated are typically springs, bearings or wear type items. You have none of those. Also many factory parts do get some strengthening from the cold working/cold forming of the parts. Your internal parts in the tie rod ends could fall into this category. Forged parts are usually just air cooled after the forging process and the slow cooling keeps from any hardening.

    BTW, even if you heat treated them prior to welding, the heat from welding would destroy any strengthening from the heat treat.

    Your adapters are the weakest link I believe. But I don;t think you are in a danger zone, the operational and even maximum stress is probably way below the material yield strength. Cut threads are not ideal, but rolled threads are not possible for you to do at home.
    Pist-n-Broke likes this.
  7. lostone
    Joined: Oct 13, 2013
    Posts: 867

    from kansas

    No suspension parts are hardened for 1 simple reason, safety.

    Those parts are made to bend during a wreck not break. That way you can try to maintain some kind of control over vehicle direction etc. If hardened they would just break during a collision and you'd lose the steering plus parts coming off the car at speed.

    So never used hardened parts on custom suspensions unless you know exactly what your doing.
    X-cpe and Texas Webb like this.
  8. error404
    Joined: Dec 11, 2012
    Posts: 132

    from CA

    I've heard of folks cryo treating certain suspension parts, but I don't think that's actually hardening it.
  9. Ned Ludd
    Joined: May 15, 2009
    Posts: 3,864

    Ned Ludd

    Could I pick your brain on something related? I'd had the idea of fabricating spindles for my Morris Minor, as that would solve at least three issues at once (lowering without messing with geometry, allow bolt-on stub-axles with better brakes, accommodate relocated steering rack) but someone on a British MM board assured me that due to metallurgical reasons it can't be done. I don't see that: the only issue I can see has to do with the fact that steering is by threaded trunnions top and bottom. Would the threads on the spindle be hardened?
  10. 97
    Joined: May 18, 2005
    Posts: 1,483


    I have been told by people in the know that better brakes and suspensions for Morris Minors come directly from Morris Marinas , along with higher horespower engines and five speed trans!
  11. earlymopar
    Joined: Feb 26, 2007
    Posts: 1,027


    Even if you did want to heat treat them, you absolutely have to know what the grade of steel is to get the proper heat treating and tempering profile. To attempt to do otherwise is truly a "shot in the dark".


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