How to remove a broken bolt and repair damaged threads?

- Jan 22, 2019-

What happens when a broken bolt or screw extraction turns into threads damaged beyond repair? Damaged threads can sometimes be chased and cleaned up with a thread chaser or tap. When they’re damaged so badly they cannot be cleaned up, your only choice is to drill them out and replace them with a Heli-Coil insert or a Time-Sert. The difference in these threaded inserts is both convenience and cost. The Heli-Coil insert is the more affordable of the two and more easily found. Time-Sert is an incredible innovation and, therefore, more expensive. Both thread repair types are available from Summit Racing Equipment.

When you are performing thread repair or replacement you must be patient. Make sure you’re using the right-sized drill bit for the damaged hole. The drill bit must be parallel to the hole. You may use a straight edge or a precision steel block as a guide, not to mention a drill press and a vice if the part can be removed from the vehicle. Always confirm accuracy before the drilling begins. Get this wrong and your troubles are only beginning.

Once you have drilled the damaged threads out, remove all the debris from the hole. When you don the correct-sized Heli-Coil tap, lubricate the threads with a Permatex Fast Break Super Penetrant and slowly run the tap. Run the tap a full revolution and slowly back out one-half turn to clear debris. Continue running the tap until threads have been cut the full depth of the hole. Wash the hole out with brake cleaner and allow it to dry.

The Heli-Coil insert is screwed into the tapped threads until seated. It is suggested you use Permatex Threadlocker on the outside diameter of the Heli-Coil insert to ensure security. Once the Heli-Coil is seated, break the tang off and you’re ready for assembly.


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