Purchase HeliCoil Thread Insert Kits at auto parts stores such as NAPA Auto and Advanced Auto Parts as of 2015. They are available in various sizes and retail for prices between around $35 to around $270.
HeliCoil is a coiled wire that adds internal screw threads that can handle standard fasteners. They contain a cross section of wire that makes it possible to screw the insert onto the threads. Working like a coiled spring, the insert compresses and expands to the walls of the threaded housing, creating tension that holds the insert in place and prevents unthreading.
Install a HeliCoil by first drilling out old threads and tapping the resulting hole with the screw thread insert. Install coarse-pitch threads by placing the insert on the installation tool and rotating the insert until the driver notch and tang come in contact. Screw the thread insert into the recommended depth, and then unthread the installation tool.
Install fine-pitch threads by first putting the insert into the pre-coil body and screwing the installation tool into the insert until the notch and tang touch and the insert is inside the pre-coil body. Screw the installation tool until the HeliCoil reaches the proper depth, and then unthread the installation tool, and remove the insert's tang.
HeliCoil offers a wide range of diameters starting at the size of a number two screw and ending at 1 1/2 inches in diameter. They are available in metric sizes and multiple lengths. Thread types offered include UNC, UNF, UNEF, UNS and pipe thread. Metric coarse and fine pitch are also available. HeliCoil is also available in many materials; stainless steel, titanium and phosphor bronze are popular choices, as well as Iconel X and Nitronic 60. Each material is available in multiple finish coatings.