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CV Axle vs steering u-joint under the seat?

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by Opast, Jun 23, 2025.

  1. Opast

    Opast New Member

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    I'm trying to decide what to use as a U-joint under the seat for my DIY 3DOF motion simulator. What do you suggest? I'm looking for something that can move 45 degrees, but I'm not sure yet if I'll need more or less. From my research so far, driveshaft U-joints don't allow much movement. I can get a steering double U-joint 1 inch or a front drive CV axle. What do you recommend? I'll be welding to 1-inch square tubing. They all cost new between $20 - $30. I think, it'll be easier to flux core weld CV axle.
    Opast, Jun 23, 2025
    #1
  2. Misanthrop

    Misanthrop Member

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    You will not need 45° at all, in my opinion 10° is sufficient.
    • Agree Agree x 1
    Misanthrop, Jun 23, 2025
    #2
  3. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    An old cat down tailshaft uni joint is a very robust option, some CV joints allow lateral movement and you don't want that.

    I agree with @Misanthrop, you will not need 45° at all. Speed and precision of motion are way more important than large angles of movement.
    noorbeast, Jun 23, 2025
    #3
  4. Opast

    Opast New Member

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    hmmm, how about something like that?

    Attached Files:

    Opast, Jun 23, 2025
    #4
  5. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    Yes an old tailshaft like that works well and is very robust.
    noorbeast, Jun 23, 2025
    #5
  6. Opast

    Opast New Member

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    Thanks, I'll check if it's available and I'll put an offer.
    Opast, Jun 23, 2025
    #6
  7. Joe Cortexian

    Joe Cortexian Active Member Gold Contributor

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    I use a Landrover PTO ujoint because it was cheap and both sides were flat plates with bolt holes.
    Joe Cortexian, Jun 24, 2025
    #7
  8. Opast

    Opast New Member

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    How about a ball joint? They are cheap $10 - $20 and new. Easy to find. What's your experience?

    Attached Files:

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    Last edited: Jun 24, 2025
    Opast, Jun 24, 2025
    #8
  9. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    A poor choice in my view, as you have to then control for lateral rotation with the likes of panhard rods, unlike a U-Joint which prevents that in a way more compact and robust form, if suitably sized.
    noorbeast, Jun 24, 2025
    #9
  10. Opast

    Opast New Member

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    Noorbeast, you really don't like my creativity :grin but I'm very appreciated for your criticism.
    • Agree Agree x 1
    Opast, Jun 24, 2025
    #10
  11. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
    3DOF, DC motor, JRK
    Sometimes the tried and trusted can save you a great deal of cost, frustration, and complexity, which is why our wonderful community is such a great resource, including providing the opportunity to bounce around creative ideas and possibly get a range of perspectives ;)
    noorbeast, Jun 24, 2025
    #11
  12. james wheeler

    james wheeler Active Member

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    I've had both and I would recommend CV shaft
    james wheeler, Jul 20, 2025
    #12