Hello all:

        I have a new problem of the spinners coming loose starting an engine.  These spinners are the type that have an aluminum backplate, an aluminum union, taped 4-40 on one end and 1/4-28 on the other end and is made from 7/16" hex aluminum.  No matter how tightly I tighten the union and the 4-40 screws, the union just becomes very loose with both the 1/4-28 and the 4-40 screws.  Perhaps the threads in the union are worn to a point to which they have insufficient metal on the threads to provide a good purchase.  This happens with both hand flipping and by using an electric starter.

      I an replacing the plastic spinners with metal Fox spinners to determine if that may cure the problem.  Perhaps I need steel unions that will not become worn so quickly.  Or blue Loctite may be the answer.

     Suggestions/comments?

                                                                                                                                             Frank

        I have a new problem of the spinners coming loose starting an engine.  These spinners are the type that have an aluminum backplate, an aluminum union, taped 4-40 on one end and 1/4-28 on the other end and is made from 7/16" hex aluminum.  No matter how tightly I tighten the union and the 4-40 screws, the union just becomes very loose with both the 1/4-28 and the 4-40 screws.

  I don't recall ever seeing spinners held on with a 4-40, but, I don't get out much.  Aluminum is OK, but only if it's one of the typical alloys (6061 T6 is probably OK, 2024 T3 is probably much better), and not just dead soft aluminum. Also, don't attempt to assemble it dry - it can easily gall on the threads when tightening, and then just rip the threads out of it. Get oil or anti-seize on the shaft and the washer, or it will try to cold-weld sometimes.

     All of mine are steel, I get the Tru-Turn adapter nuts, because that's what works with Tru-Turn spinners (with a 10-32 thread, I think, I never actually checked it). I have various modified 1/4-28 adapters with parts cut away, to permit adjustment of the CG in very fine increments. It's a lot more forgiving than aluminum and it only takes a little oil.

   If you are really damaging the threads, loctite won't help, it might not spin out on it's own, but it also won't stay tight.

    Brett