After 9 years

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    Brought my frame home today to start to reassemble the car.

    PA Frame


    I am in need of the threaded plugs that go in the spring shackles. Anyone have any?


    PA frame


    Are those plugs 1/8″ NPT?



    They are almost 1 1/2″ in diameter and the thread count is in the 20 TPI range and I don’t think it has a taper.

    The threads are pretty fine for that OD.

    I am afraid they are going to be one of the Pierce only products,  courtesy of the Pierce engineering staff.




    Bill, This sounds like your spring pivots may be the (old) UNEF thread standard that were 18 threads per inch in this size range (dimensions are published on-line). Unusual, but not unheard-of for this era of manufacturing. Measure the thread inside diameter carefully (use a T gauge & micrometer) plus a thread gauge to verify the pitch, then consult a thread chart (table) before assuming the size.   During this period, bolts were made on screw machines and lathes that had fixed gears to set the threads-per-inch, so some unusual combinations came about (such as the 14 thread-per-inch series).

    Looking in my 1929 parts catalog, the front mount of the springs is not complex and the threads are likely to hold retainers that give the spring a vertical pivot but prevent horizontal movement.  Check with John Cislak, as he advertised shackle set for the older models and they are likely to be quite similar. Even if you need them custom-made, they are not that complex.

    In any event, measure the threads carefully and consult a thread chart (table) before assuming the size.  Taps to clean up the threads in your spring hangers are available, but rather expensive.  Herb



    I totally spaced it I was thinking of a grease fitting and wondering why you showed the picture of tht BA threaded hole. Do you not have 1 plug you can measure?




    With a telescoping ID gauge I am getting 1.445″ for an ID and it looks like 18 TPI.

    So my guess looking at the charts is 1 1/2″ -18 UNEF.

    Anyone have one I can beg, borrow, rent or purchase?


    Hi Bill,

    I have a few rear plugs (the ones with 8 spanner holes – picture below of one and spanner I made), but don’t know how many I need for all my projects.  You are welcome to one, including the locking plate.  I can actually supply 4 locking plates (enough for all 4 rear plugs).  The rear plugs are 1-11/16  –  20, and the front plugs (serrated edge) are 1-1/2 – 20 threads.

    I don’t have any extra front plugs.  I do have several “dogbones” that the bearing cups go in if you need those.

    I am in need of a 1933 lighting switch at the bottom of the steering column, art deco (chrome stripes) glovebox door panels, and a salon right side taillight lens bezel for my 1242.

    If we can’t work a trade, you can have the rear plug and 4 lock plates for $50 ppd.

    Best regards,







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