Crossthreaded upper ball joint

Brakes, Suspension, Rims and Tires

  1. JG1966

    JG1966 Well-Known Member

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    I believe I crossthreaded one of my new upper ball joints (72 RR). It is completely seated (after much effort) and torqued to 120 ft/lbs.
    I didn't realize it was crossthreaded because it was such a pain to take old one out and I didn't think twice about it being difficult to screw new one in. So I just kept seating it (even though I knew they were prone to stripping/crossthreading!).
    But when the other ball joint went in easily, I then realized I may have crossthreaded the first one.
    Assuming this ball joint will never need to be replaced, am I OK -- or is a crossthreaded ball joint more likely to fail? It's seated level and torqued to 120 -- and I guess it's possible it wasn't crossthreaded. But I worry if threads were crossed it may be weakened or a problem/disaster waiting to happen. I'll yank UCA (it's 45 years old) and put in new arm and ball joint if I have to. But if crossthread is no big deal (other than if I ever need to remove it), then I'll not worry. Thanks for any advice.
     
    Last edited: Jun 19, 2017
  2. Cncguy1

    Cncguy1 Well-Known Member

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    Get a new A arm. It's possible it will stay, but if it fails it will be catastrophic.
     
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    • 65RoadRacer

      65RoadRacer Well-Known Member

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      I agree... this is your suspension/steering/handling.... if you suspect it's cross threaded, I would venture to say that the cost of a new UCA and ball joint are good insurance that you don't have a catastrophic failure. The forces your car can put on that ball joint are far greater than what you could assimilate yourself. It sucks, but remove the arm and see if you can remove the ball joint and visually inspect it - cross threading will likely be easy to tell. It's worth it to at least do that much.
       
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      • Mike67

        Mike67 FBBO Gold Member FBBO Gold Member

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        I think Cranky has some for sale, check the Mechanical parts forum.
         
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        • STREETREBEL

          STREETREBEL Well-Known Member

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          I just added 4 spot welds to mine.
          No problem here.
           
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          • HT413

            HT413 7T 451

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            new a arm is the only answer. A arms don't go quietly.
             
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            • PRND21

              PRND21 FBBO Gold Member FBBO Gold Member

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              Take it back apart. If it's cross threaded it will be obvious. If it is, one part or the other may not be damaged. If not reassemble with a drop or two of lube.
               
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              • HT413

                HT413 7T 451

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                Yeah I was just thinking, if its not cross threaded, I wonder if there is some corrosion in the treads or perhaps the threads were damaged sometime in the past. A close inspection is warrented here, though either way I'd be replacing it.
                 
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                • moparnation74

                  moparnation74 FBBO Gold Member FBBO Gold Member

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                  Or the nut is spinning, hence damage threads....

                  Either way....The sound advice is to replace....
                   
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                  • JG1966

                    JG1966 Well-Known Member

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                    Thanks for replies everyone. I just ordered new arms from P.S.T.
                     
                    Last edited: Jun 19, 2017
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                    • Dako

                      Dako Well-Known Member

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                      Think about the geometry of the suspension. The lower ball joint holds the weight. The upper keeps the spindle plum.You got it to fully tighten an torqued. You'll be fine.
                       
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                      • cryplydog

                        cryplydog FBBO Gold Member FBBO Gold Member

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                        I cross threaded my upper on the drivers side so I disassembled it and I don't recall the tap size but it was a pipe thread I think about 1-1/4 NPT and chased the treads on the upper C/A then screwed the upper ball joint back in and then I put about a 3/4" weld on three spots on the side facing outward so I could grind them off if I ever need to remove it again. As weak tit as the factory threads are I decided that would be my standard procedure from now on. Good luck
                         
                      • 69L48Z27

                        69L48Z27 Well-Known Member

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                        I did mine over the winter and one side was easier than the other. I kept checking for cross threading but it wasn't. If your cross threaded the flange of the ball joint will NOT be sitting flush all the way around with the A-arm. If its flush and you got the 120ft/lbs your good to go.
                         
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