A nut on my bike is rusted and doesn't accept a bolt beyond first few threads.

What can I do about it short of grinding it off and welding a new one on?

2 Answers 2


Either use a freeing fluid such as "plus-gas" (btw WD40 is not the same WD stands for Water Displacement...) and gently work the bolt through. I have had success with getting a duplicate bolt and putting a hacksaw cut into the threads to help chase the rust out.

Or get the correct tap and re-tap the threads in the nut.


I would "clean" the rust out by re-tapping with the proper thread tap.

Thread tapping

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  • 1
    The image shows what is called a bottoming tap - a starting tap has a more pronounced taper and is easier to start.
    – Solar Mike
    Aug 16, 2018 at 6:27
  • Spot on. Honestly, I'd use [and have used] the "bolt slot" method if it wasn't for the fact I own a machine shop and drawers chuck full of taps. If the bolt, when tight, extends several threads past the nut, you can make a minor cut on the tip and use the same bolt. But I'm one of those people that can't imagine not owning every single tool - usually purchased after I use some shadetree method. For next time, see...
    – SteveRacer
    Aug 17, 2018 at 4:05
  • I used the bolt-slot method out in the middle of a field on a tractor - no drawers of kit available :) :) just what you can come up with...
    – Solar Mike
    Aug 17, 2018 at 4:32
  • If there's no room for a tap there are socket sized adapters.
    – geoO
    Aug 17, 2018 at 12:53

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