A Torx® socket is a tool used to remove Torx®-type fasteners. These fasteners differ from the common hexagonal nut and bolt in that the Torx® fastener has a six-pointed star-type head that must be used with a Torx® socket. Much in the same manner as an Allen bolt uses a specialized hexagonal tool to fit inside the bolt's head, the Torx® socket fits snugly within the head of the Torx® fastener to allow tightening and loosening without the tendency of striping or rounding the fastener so that the wrench will no longer fit the head of the fastener. It is critical to use the appropriate-sized tool when removing a Torx® faster, as it is possible to insert a smaller tool inside a fastener's head, which will result in stripping the bolt's head.
Many automobile manufacturers switched from hexagonal bolts and nuts to Torx®-type fasteners in the mid 1980s to reduce the number of stripped and damaged fasteners found on the finished production vehicles. By using the new fasteners along with the Torx® socket, the amount of damaged fasteners found on the newly-built vehicles was drastically reduced. In performance automotive shops, the use of the Torx® socket and the new fastener provided a much more accurate torque application to critical high-performance engine components such as the main bearing caps and head bolts.
It is not impossible to strip a fastener while using a Torx® socket, although it is a rare occurrence in most applications. The typical cause of stripping a fastener when using a Torx® socket is the use of an improperly-sized tool for the fastener or the improper application of the tool. Placing a socket only partially on or in the fastener will sometimes result in a stripped fastener as well as a damaged tool. Placing the tool completely on or into the fastener will usually result in many use cycles of a fastener without causing any damage to the fastener or the tool.
If the edges of the Torx® socket become slightly bent or twisted due to extreme force being placed upon the tool, a few strokes with a quality metal file will usually straighten them back to their original shape and configuration. Using a damaged Torx® socket on a new fastener will occasionally damage the fastener. By maintaining the tools and inspecting the condition of the six-pointed star, any damage will be found and the broken tool can be replaced prior to damaging any fasteners.