Heli-coil R1185-04 Free Running Insert 4-40 Unc 12 Pack

Product Description

The HELI-COIL R1185-04 is a free running helical wire thread insert designed to create durable, standardized internal threads in tapped holes. Built from stainless steel, this tanged insert accepts 4-40 UNC thread fasteners and measures 0.168 inches overall length. Free running inserts allow unrestricted fastener rotation without locking resistance, making them the standard choice for thread repair and thread reinforcement in soft or worn base materials. This package contains 12 inserts. Installation is performed by machinists, maintenance technicians, and field service professionals working across mechanical assemblies, HVAC equipment housings, and light structural components.

This insert is suited for applications where a 4-40 UNC threaded hole needs to be repaired, reinforced, or established in a host material that cannot reliably hold a direct-cut thread. Common install scenarios include restoring stripped threads in aluminum, magnesium, plastic, and cast iron components, as well as adding thread inserts during original assembly to extend service life. The stainless steel construction provides corrosion resistance in environments with moisture or chemical exposure.

Key Features

• 4-40 UNC thread size for compatibility with standard number-4 coarse-thread fasteners
• 0.168 inch overall length for use in thin-wall and space-constrained host materials
• Stainless steel construction resists corrosion and wear
• Tanged design allows controlled installation with a standard HELI-COIL installation tool
• Free running style permits unrestricted fastener engagement without locking torque
• Package quantity of 12 inserts per unit

Compatibility

Designed for use in any host material tapped to the HELI-COIL 4-40 UNC insert specification, requiring the corresponding drill and tap size per standard HELI-COIL installation guidelines.

Installation Notes

Thread insert installation requires drilling the damaged or base hole to the HELI-COIL specified oversize drill diameter, then tapping with the matching HELI-COIL tap before driving the insert. A dedicated HELI-COIL insertion tool is required to wind the insert into the tapped hole without damaging the coil. After installation, the drive tang must be broken off using a tang break-off tool or long-nose pliers. Always de-energize and isolate any equipment before performing thread repair on live assemblies.