What causes the car to understeer and oversteer

Discussion in 'Suspension, Steering and Chassis' started by Steve Agrella, May 17, 2018 at 10:05 PM.

  1. Steve Agrella

    Steve Agrella Well-Known Member

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    Not sure if these are the right terms to use, just had the front end completely rebuilt except for the steering box.
    The car tends to keep wanting to go in the direction of compensation, fighting it going back and forth, there’s about an inch of play both ways on the steering wheel,.
    The mechanic told me it was the best he could do, he told me that if he adjusted anymore it started to bind.

    Seems to be be a slight clunking sound if I rock the steering wheel back and forth
     
  2. dano

    dano Evil Handy Man

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    What you describe is not over or under steer. Those are terms used for how a car "plows" in a corner.

    Something is wrong, either the rebuild was not done correctly, something is loose, the steering u-joint is messed up, the steering box is out of whack, your alignment is a mess, tires are trashed, and possibly bad or improperly installed wheel bearings just to name a few. Find a competent shop and have it looked at ASAP because something is not right and potentially dangerous.
     
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    • 67Dart273

      67Dart273 Well-Known Member

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      Get a friend. have him/ her move the wheel left right until the "play" in the wheel starts to move something. You get down and LOOK.

      Look at the steering column and steering coupler. As the column shaft moves the coupler should follow exactly with no lost movement

      Move to the pitman arm, look at it along with the column shaft. There should be almost no lost movement there, either

      Move to the end of the pitman arm. Watch the arm vs the ball end. Should be ZERO detectable play........if the long end of the pitman moves, the ball end should follow.

      Move to the idler arm. You should detect almost no or no movement up and down as it starts to move left/ right.

      Move to the outer / inner tie rod ends. Same deal, the "rod" part of the thing moves, the "nut" on the ball end should follow with no detectable play.

      Look for movement of the steering gearbox housing in the frame. Should be ZERO

      Getting the idea? Take a specific piece that moves, and verify that it moves as it should, with no play if it should not have any, and so on
       
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      • rustycowll69

        rustycowll69 Well-Known Member

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        I agree with previous posts. It kinda sounds like what I had with my 66 cuda. The steering box came loose and broke the mount on the k-frame. But it could be any of the other previously mentioned points, as well.
         
      • Streetsboro Rick

        Streetsboro Rick Well-Known Member

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        Did you have the column out if so is coupler put back together correctly? Correct pitman arm? Idler arm?
         
      • jdsduster

        jdsduster Well-Known Member

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        you should be answering questions in a car magazine.great answer
         
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        • 67Dart273

          67Dart273 Well-Known Member

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          Thanks, I left out.......since the OP asked about the steering box.........watch the column shaft move along with the pitman arm. You can usually look down from the top and see them both, use a light. "Lost movement" AKA the column shaft moves but the pitman delays movement........you have found the loss within the steering box itself.

          Refer to the factory shop manual !!!! ADJUSTING the box IS NOT JUST turning the screw adjustment. Read the manual for procedure. Play can also be, EG......slop in the lower pitman bushing not just play in the sector gear teeth.
           
        • Frnknsteen

          Frnknsteen FABO Gold Member FABO Gold Member

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          Even if you didn't have it apart, if it is possible that someone else did I would check it. I had excess play in my '67 Barracuda steering, even after I replaced all the suspension parts. Turns out the previous owner must have pulled the coupler apart and put it back the wrong way at some point. There are two little blocks in there that slide over pins, and there is a spring that pushes them outwards to contact the coupler body. I am attaching a picture I found online. Make sure the blocks are positioned as shown in the picture.

          They can be installed two ways, but only one works. It is easy to insert them with the rectangular blocks aligned with the shaft, but that is wrong. They need to be perpendicular to the column shaft so they just slip into the coupler with very little movement, then pack the coupler body with grease and put the seal plate down in place.

          Coupler.jpg
           
        • Steve Agrella

          Steve Agrella Well-Known Member

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          Thanks for all of the replies, I just got this car so haven’t really had much of s chance to play around with it yet.
          I took it to good year tire, the told me everything in the suspension had been replaced except for the Upper and lower control arm bushings so I paid them to do that.
          They also showed me while the car was on the rack that idler arm was loose they tightened that.
          The Mech also told me that the steering box was a rebuilt, found out this morning that the Power steering pump was empty?? Lots of surprises
           
        • Steve Agrella

          Steve Agrella Well-Known Member

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          I did a video this morning while in the car turning the wheel slightly left to right motor not running the steering box is moving around slightly like it’s not tightened down
           
        • KosmicKuda

          KosmicKuda Well-Known Member

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          What year and model car do you have?

          The 3 steering box mounting bolts tend to loosen up over time especially if its been replaced. I've seen it multiple times.

          If the car was aligned using the factory specs it will tend to be unstable. I like 2* positive caster, .5* neg camber and about 1/16" toe-in. You typically cannot get enough caster using stock components so I replace the UCA bushings with Moog Problem Solver eccentric bushings.

          My 68 with 215-60x15 front tires with those alignment specs tracks like a freight train with no hands on the wheel. You must tell the alignment tech what specs to use though.
           
        • 72bluNblu

          72bluNblu FABO Gold Member FABO Gold Member

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          Well it may just not be tightened down. The torque spec is pretty high for those bolts. I forget exactly what it is off the top of my head, but if it wasn’t torqued properly the bolts can loosen up.

          The steering box mount may also be damaged. That’s what happened on my Duster. The welds holding the steering box mount to the K-frame cracked, and the whole mount would flex back and forth when I turned the wheels. If that’s the case the K-frame will have to be pulled out and welded.
           
        • rustycowll69

          rustycowll69 Well-Known Member

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          that's how I fixed mine. I had Dan H. in Milton reweld the mount on the K-frame. I believe I had him add a gusset or two while he was at it, also.
           
        • Steve Agrella

          Steve Agrella Well-Known Member

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          I stole this car so bring it on.... lol fun fun fun
           
        • 72bluNblu

          72bluNblu FABO Gold Member FABO Gold Member

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          It’s a pretty common place for the welds to fail. The factory welds weren’t always great, some K’s were a lot better/worse than others.

          I seam weld and reinforce all of my K frames. The steering box mount and LCA pivot mounts get gusseted, I add a skid plate, etc, similar to what Firm Feel does for their K frame reinforcement package.
           
        • AJ/FormS

          AJ/FormS 367 FormS clone 3.09-1.92-1.40-1.09-.78od 3.55s

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          That's classic binding in the new parts themselves.