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traction bars

Discussion in 'The Garage' started by blazerpro79, Mar 5, 2005.

  1. blazerpro79

    blazerpro79 1/2 ton status

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    hey i read a thread about making a traction bar...
    how would you go about doing that?

    would you just weld some tabs to your frame and axle, and attach them with a bar? sounds easy enough.

    is there any geometry to it?
     
  2. dirtwarrior17

    dirtwarrior17 Banned

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    sounds like a sway bar to me.
     
  3. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    There's a little more to it than that......


    Here's the hint:

    When you mount a bar between the axle and the frame, you have now constrained the axle to a specific arc of travel, both up and down

    Compare that to the arc of travel on a leaf-sprung (and rear shackled) axle, you'd notice that the axle travels UP and then BACK as it compresses...and DOWN and FORWARD as it droops.

    My guess is that those two "arcs" are NEVER going to be the same. Most decent traction bars for 4x4s employ a slipjoint or other technique to allow the bar to more closely follow the rear axle/leaf spring motions. If these two arcs don't match...they suspension will fight itself and bind-up badly.

    There are quite a few pics posted up in this forum lately, so look around and you'll see examples of things people have done that seem to be working. :cool1:


    .
     
  4. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Assuming you want an anti-wrap bar that works properly off-road, yes, geometry is very much involved. In addition to (or related to) those already mentiond, and depending on design, there are many potential issues including anti-squat/jacking, axle steer, and even compression vs. tension shackle (assuming you use a design that needs one). There are designs that use the single bar, but they have potential issues too. So to answer your question, "traction bars" on off-road vehicles are not nearly as straight forward as they seem. Searching will yield a few threads that go much further into specifics.
     
  5. Silver84k5

    Silver84k5 1/2 ton status

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    correct if im wrong. but.. The closer to the Center of the axle that you mount the Bar, The less it is gonna hinder Suspension travel?
     
  6. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    That's an over simplification, but sorta. The axle movement relative to the frame will be less as you get closer to center, but improper design could still bind just as bad.

    And this is not to say some simple designs just thrown together won't "just work", but if you didn't just "get lucky", then it may "work fine" only because you haven't noticed the problem or put it into a situation that would accentuate the problem. For instance, on my recently deceased rear leafs, i created a pretty cool traction bar, or so I thought. However, I didn't account for the large amount of axle steer at extreme articulation and that resulted in a bent 3/8" plate used as a mount along with two crushed 1" x 0.120 spacers and bent 5/8" bolts. And mine was located as close to center as you can get with a 14 bolt.

    Oh, and you generally want a typical anti-warp bar on the passenger side to use anti-squat to counter engine torque. On the driver's side it will add instead of subtract giving you more acceleration body roll.

    Starting to get the picture? ;)
     
  7. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Anyone else remember Borrego's anti-wrap bar? Hard throttle in a left turn would pick the front tire right up off the ground...

    Rene
     
  8. AkMudr

    AkMudr 1/2 ton status

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    I'm all about the Fabritech Stage 2's. BLING!!:woot:
     
  9. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    LOL, hadn't thought of that in a while! Looked cool though didn't it? :crazy:
     
  10. 81jimmyslt

    81jimmyslt 1/2 ton status

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    Check out the vendor forum MOO just released their sweet traction bar.

    drool........................................................................................
     
  11. dirtwarrior17

    dirtwarrior17 Banned

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    whats the difference between a traction bar and a sway bar?
     
  12. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Traction bars are better called "anti-wrap bars" and they are used to keep the rear axle (or sometimes front) from "wrapping" the springs into an "S" shape. The wrap-unwrap cycle that results causes the axle to hop and all sorts of bad stuff, including loss of traction.

    Sway bar helps resist side to side body roll relative to the axle. Totally different things.
     
  13. dirtwarrior17

    dirtwarrior17 Banned

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    had it start hoppin on me in the middle of a hill climb.... felt like an earthquake and sounded horrible.
     
  14. RustBuket

    RustBuket 1/2 ton status

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    And then the u-joints or axles shafts like to go boom!
     
  15. mud hungry

    mud hungry 1/2 ton status

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    I saw a guy once had four shocks mounted. to were for the up and down movement and the other two were mounted more to the front of the axel and mounted to the top to act as anti-wrap. Does anyone know if this will work. It sounds as a poor mans antiwrap system.
     
  16. dirtwarrior17

    dirtwarrior17 Banned

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    actually i have that setup but with two shocks instead of four... or maybe its three in the back. don't remember but that was the only time i've had axle wrap bad enough to say anything about it.

    I have on shock mounted vertically and the other is mounted horizontally in the back. in the front its both vertical.
     
  17. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    That is axle wrap, and now you know why we all hate it enough to build anti-wrap bars. if violent enough it can and will destroy U-joints and drivelines. It also doesn't do the springs a world of good.

    Rene
     
  18. dirtwarrior17

    dirtwarrior17 Banned

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    yeah, i always used the term wheel hop...
     
  19. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Wheel hop is just the end result. Axle wrap would be the correct term...

    Rene
     
  20. RustBuket

    RustBuket 1/2 ton status

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    The shock method works good for axle wrap that is only induced over a short burst. But in a situation where torque is constantly applied, the springs will just wrap up slower.
     

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