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what is death wobble

Discussion in 'Chit-Chat' started by concretejungle, Aug 16, 2005.

  1. concretejungle

    concretejungle SILVER Star

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    Had a local kid with a jacked-up jeep ask me if i am having any problems with death wobble? WTF? never even heard of that. He said he can't go over 35mph without almost losing control of his rig. What is death wobble? I have heard of it when i was a kid screaming down the street on skateboards, but not vehicles.
     
  2. 2badfjs

    2badfjs

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    same as a skateboard,but in the front end.
    feels like everything is coming apart.
    could be tire balance,trunion bearings,tre's
     
  3. mabrodis

    mabrodis

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    I don't know the technical definition of it, but it's when the vehicle's suspension and steering are somewhat at odds with each other. So the suspension moves pushes the steering one way, then the steering equipment fights back and pushes the suspension. It usually happens on vehicles where the steering and suspension have been modified, so the steering is at an angle where more bumpsteer can happen, larger tires can be more out of balance and can trigger it. When death wobble (DW) kicks in, usually there is nothing that can be done, you just have to slow, sometimes to a dead stop, then start out again. It basically is a visious cycle between the suspension and steering, and you can't break that cycle until you slow way down or stop.

    Do some searches in the 40 and 60 forums, you'll see writeups on it, it definetly can happen, my 40 had it horribly bad, for me it was all tires (that triggered it, having modified suspension and steering doesn't help the situation though)...some say loose knuckles and TREs can trigger it, but I've never seen those play any part at all in it, and I've seen 40's with 30 yr old TREs and knuckles horribly worn, and they had no symptoms of DW whatsoever.

    Many jxxps get DW (solid axle, more bump steer when lifting, etc), I have several friends that fight it on a week by week basis to minimize it.
     
  4. woody

    woody unhelpful spotter Staff Member Admin

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    death wobble is caused by a pile of things.....loose wheel bearings, unbalanced tires, bad tie rods, bad spring bushings, loose u-bolts, bad kingpin/trunion bearings, too light of preload settings on bearings, and a host of others....

    the description is right on....driving down the road, hit a certain speed, and the front tires suddenly vibrate back-forth, WAY beyond what your hands can control....you can either A> attempt to drive thru it, usually a 15mph speed increase will ditch it, or B> come to a stop/near stop, and then do NOT approach the death wobble speed again.

    Driving thru is dangerous, since having the power to accellerate quickly thru that wobble isn't always possible....the wobble can either start "on its own" or can be jump-started by crossing a bumpy road section like railroad tracks or a bridge.

    The cure is time consuming, and consists of major maintenance and adjustment of ALL front axle related items, steering, tie rods, toe settings, tire balance/pressure, torque settings, etc....
     
  5. dmc

    dmc

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    My 40 had it bad. Even broke a front spring hanger because of it. I tried everything, bearings, TRE, tires, pitman arm etc. Nothing fixed it. Final solution? Ditched that damn old coarse spline axle and upgraded to a disc brake front. It magically disappeared. I don't even run a stablizer now.
    dmc
     
  6. Greg_B

    Greg_B

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    And even all of that and more does not work sometimes. The only thing that solved mine was a steering damper from axle to tie rod. Relay rod to frame did nothing...

    gb
     
  7. mabrodis

    mabrodis

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    The only thing that cured mine was rebalancing tires, rebuilt entire frontend, everything was tight...still would DW horribly bad...but wasn't consistent, would be ok then when hit a bump wrong...eeek...hang on!
     
  8. zetasig

    zetasig

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    I have also heard it called bump steer. I think meaning the bump starts steering the vehilce where you dont really want it to go.
     
  9. Gumby

    Gumby Supamod Staff Member s-Moderator

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    Bump steer is different. Bump steer is when you hit a bump and the steering reacts. Pretty common in primitive steering linkages. Worse if your geometry is off.

    Death wobble is an oscilation that gets worse. The whole damn truck shakes back and forth.