Rethreading Nuts and Bolts, a Guide

No matter how careful you are when you reinstall old rusty nuts and bolts, someday you’re going to strip some threads. Of course, it will happen on a critical bolt, on a Sunday night when all the stores are closed. That’s when a thread restoration kit pays for itself. You’ll be done rethreading your bolts faster than if you’d gone to the store. And you’ll have saved yourself the frustration of trying to match up specialty bolts.

What Is a Thread Restoration Kit?

A full set (metric and SAE) will quickly put irreplaceable and hard-to-find nuts and bolts back into service. The rethreading tools look like traditional taps and dies. But instead of cutting new threads, they reshape them to original condition.

How to Rethread Nuts and Bolts

To restore bolt threads, follow these steps:

• Start by finding the thread count (SAE) or pitch (metric).
• Hold the thread file against the bolt threads until you find the size that matches.
• Clamp the bolt in a vise, engage the thread file grooves with the bolt threads and push the file.
  • Note: This resets the threads enough so you can screw on a rethreading die. Be sure to apply a few drops of oil first and then screw on the die.

To clean rusty or stripped nuts and bolts, follow these steps:

• Grab a rethreading tap from the kit to restore threads on nuts or threaded engine component holes.
• To begin, insert the rethreading tap or die and rotate a few turns, then back it off a full turn. This will dislodge the debris from the teeth.

Don’t try to rethread the entire bolt, hole or nut in one operation. Go slowly so you don’t force things and damage the bolt you’re trying to fix. A little patience will pay off; it will still be faster than searching for a new one at the store, and it’s a skill that is handy to have in your back pocket regardless.