tap for shackle nuts- tubes?

Kdancy
Kdancy Senior Contributor
edited November -1 in HUDSON
Does anyone know if a tap is made that will work for leaf spring shackle nuts? I want to clean out the shackle hanger tubes that are welded into the frame before screwing in the shackle tubes ?? Hope that made sense ---

37 Terraplane.

Comments

  • Uncle Josh
    Uncle Josh Senior Contributor
    Yup, they're called heavy duty wire brushes. Then use some Anti-sieze.



    I dunno, never heard of them, but that doesn't mean they're not out there.
  • bob ward
    bob ward Senior Contributor
    The outer thread on the shackle nut tubes is a special form used back when in the auto industry, nothing standard today matches it.



    If you know someone with a lathe who owes you a favour, they could make a tap good enough for cleaning out a few tubes.



    Other than that I'd be thinking of a wire bottle brush or similar in a drill to clean out the threads.
  • bob ward
    bob ward Senior Contributor
    Out of curiosity about the oddball thread on the OD of the shackle tube, I dug out my NOS shackle tubes and hanger bolts.



    The thread on the hanger bolts is 11/16" x 11 TPI, and its a standard 60° thread form.



    The shackle tube thread is 7/8" x 11 TPI, but its a very shallow thread form, maybe 120°. So why would Hudson use this oddball thread form?



    I'm thinking they were worried about the shackle tube becoming too thin. If you do the sums, the shackle tube wall before cutting the outer thread is 3/32" or 94 thou thick.



    A standard 60° thread would cut down into the shackle tube about 45 thou, but a 120° thread, if thats what it is, would only cut down about 25 thou, leaving a bit more meat in the wall.
  • Uncle Josh
    Uncle Josh Senior Contributor
    It would be pretty simple to use an extra tube with decent threads on it, and grind a cutting edge on the end, something like a tap. That would take care of the frame tube.



    Do a similar thing to an extra left-hand shackle and sharpen both right and left hand threads so you can clean out the lower tube which is a left-hand thread.
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