Heli-coil 5521-14 Thread Repair Kit 7/8-9 Unc 6 Inserts

Product Description

The HELI-COIL 5521-14 is a threaded insert thread repair kit designed to restore damaged or stripped internal threads to their original specification. The kit covers the 7/8-9 UNC thread size with an insert length of 1.312 inches, making it suitable for heavy fastener applications where thread integrity is critical. It ships as a complete, ready-to-use package that includes all the tooling required to complete the repair without sourcing additional components. Machinists, maintenance technicians, and field service professionals use this kit to restore thread engagement in metal workpieces where re-tapping to a larger diameter is not an option.

This kit is used in manufacturing maintenance, equipment repair, and field service applications involving UNC-threaded fasteners in the 7/8-9 size range. The 1.312-inch insert length provides extended thread engagement, which is well-suited for high-load or high-vibration environments. The complete tooling set included allows a single technician to carry out the full repair sequence from drilling through insert installation on-site or at a workbench.

Key Features

• 7/8-9 UNC thread size for standard unified coarse thread repair
• 1.312-inch insert length for extended thread engagement in high-load applications
• Includes drill, tap, installation tool, and tang removal tool for a complete repair sequence
• 6 threaded inserts included per kit
• Installation tool part number 3724-14, tap part number 8187-14, insert package part number K1185-14
• UNC thread standard compliance for compatibility with standard unified coarse fasteners

Compatibility

Designed for use in applications requiring 7/8-9 UNC threaded insert repair using the HELI-COIL system. Component part numbers included in this kit are 3724-14 (installation tool), 8187-14 (tap), and K1185-14 (insert package).

Installation Notes

Installation should be performed by a qualified machinist or maintenance technician familiar with thread repair procedures. Before beginning, ensure the workpiece is de-energized or depressurized and secured against movement. Follow the drill, tap, and insert installation sequence using only the included tooling to ensure proper thread form. Remove the tang after insert installation using the included tang removal tool.