Installing Helicoils
Helicoil is a trade name for a thread replacement insert and tool system. All Helicoils come with a small kit in which damaged female threaded holes can be repaired, and a new bolt inserted for fastening parts together. In most cases, installing a Helicoil takes less than a ½ hour of time if the damaged bolthole is clearly accessible.
Enlarge the Damaged Bolt Hole
Consult the Helicoil specifications and insert the correctly sized drill bit into the drill motor. Hold the drill motor at a right angle to the damaged hole. Drill out the damaged threads to the proper depth as listed on the Helicoil specifications for that particular thread repair kit. Various sizes of Helicoils will require different depths of holes for the thread repair insert. Remove all foreign debris from the drilled hole. Any particles left in the hole will interfere with the proper insertion of the thread repair.
Tapping the New Threads
Install the Helicoil provided tap into a tap handle tool. Add a few drops of machine oil to the threads on the Helicoil tap. Hold the tap at a right angle to the drilled out hole. Carefully turn the tap in a clockwise direction into the drilled hole. Progress one full turn at a time, and then back out the Helicoil tap in a counter clockwise direction. Remove the metal debris that has accumulated inside the tapping threads. Proceed in this same fashion until you have reached the correct depth of the drilled out hole. Failure to remove the tap after each full turn, may cause the tap to break off in the hole.
Install the Helicoil
Place the Helicoil insert onto the mandrel of the provided installation tool. Carefully thread the Helicoil into the newly tapped hole. The Helicoil insert should screw into the hole very smoothly. If you feel some resistance, withdraw the Helicoil and clean out the hole. Continue to wind the Helicoil into the hole until the top of the coil itself is ¼ to ½ turn below the top surface of the hole. Withdraw the installation tool from the Helicoil insert. The Helicoil has a lower tang on the bottom of the coil. This tang must be removed prior to installing the new bolt. Slide the tang break off tool through the new Helicoil. The break off tool comes in the Helicoil kit. Push the tang break off tool until its bottom mates up against the lower tang. Use a hammer and strike the top of the break off tool twice. The tang should have broken off. The tang for larger Helicoil inserts with diameters of a ½ or greater, can be removed by placing the jaws of a needle nose pliers around the lower tang. Rock the pliers back and forth until the tang breaks free. The new bolt is now ready to be installed.
