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is it safe to re-tap lug threads?

The local tire shop cross threaded one of the lug bolts on my 2000 VW Passat. About 1/2 to 1/3 of the threads on the bolt that normally engage were damaged. I could not turn another lug bolt into the female threads in the hub without it trying to cross thread, so the wheel hub threads were clearly damaged too.



The tire shop offered to "correct" the problem by tapping new threads into the wheel hub. I'm concerned that the metal that composes the new threads will be fatigued and thus not as strong.



The tire shop said this is a safe fix, but I'd like another opinion, as they are bound to be biased by the fact that it's cheaper for them not to replace the wheel hub.
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Comments

  • edited January 2011
    I'm no expert, but I side with you.
  • edited January 2011
    Can the lug be torqued to the correct value? even a brand new lug stud on a brand new car can fail. If you are looking for a mechanical device with no potential for failing I think all there is, is a steel ball (and my old man said I could cause that to fail)
  • edited January 2011
    On most cars, individual wheel studs can be replaced at a cost of only a few dollars.
  • edited January 2011
    Some German cars (including mine) have lug bolts instead of lug nuts. The female threads are in the wheel hub instead of in the lug nut. In this case, those threads are built into the wheel hub and cannot be replace independently. Otherwise, this would be the obvious choice. Thanks for the suggestion though!
  • edited January 2011
    I see. I vote for replacing the hub and restoring your car to the condition that it was in before they messed with it. However, I don't think there is a real safety issue with their proposed repair.
  • edited January 2011
    That is a good point. Brand new and normally used metal parts will have a failure point, probably in response to a normally distributed amount of force, and this is taken into account when the car is designed. If you fatigue the metal, it will have less safety margin.

    The lug threads certainly need to be strong enough to allow for proper torquing, but need to support the force of a 3,000 vehicle in a turn in addition to the constant force of the tensioned lug bolt.
  • edited January 2011
    Cool, thanks for your thoughts!
  • edited January 2011
    Heli-coil the failed threads. The heli-coil will be at least as strong as the originals at a much lower cost than replacing the hub.
  • edited January 2011
    A rethreading tap and die can be very handy. First, I would question anyone who would cross thread a lug nut as it shouldn't really happen but it does. The rethreaders will clean up the problem without taking out a lot of metal. The damage has always seemed in the first 4 or 5 threads with no damage in the threads that get the torque. But if the stud is available replacenent is certainly preferred and the shop shouldn't quibble over it.
  • edited January 2011
    If this was my car I would at least want the hub to be removed and a thread chaser used from the back side rather than a tap from the front side which would remove metal. After that I would want the lug bolt to be proofed by torquing it to 110% of the specified value, then loosened and torqued to 100%.

    My VW parts catalog does not include a hub for a Passat but shows a price range for Golf/Fox/Jetta front hubs of $18 to $50. That would not be difficult for the tire shop people to handle. They should caution their people to not use an impact wrench to start a lug bolt or a lug nut which I am guessing what happened. It would be difficult to ruin a lug bolt/nut thread when starting it by hand and using a little care.
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