Heli-coil AT1185-4C375 Thread Insert 1/4-20 Unc 0.375 in

Product Description

The HELI-COIL AT1185-4C375 is a free-running, tangless wire thread insert designed to install and repair 1/4-20 UNC threaded holes in parent materials that need reinforced, wear-resistant threads. Made from 304 stainless steel with a bright, uncoated finish, this insert delivers a 1-1/2D length-to-diameter ratio at 0.375 inches overall length. The tangless design eliminates the need to break off a tang after installation, reducing debris risk in blind holes. Maintenance technicians, machinists, and field service professionals use these inserts to restore or upgrade thread strength in aluminum, cast iron, and softer base materials.

This insert is suited for both original equipment manufacturing and field repair applications where a 1/4-20 UNC thread form is required. Typical installations include threaded holes in housings, brackets, enclosures, and structural components across HVAC equipment, electrical panels, pump bodies, and general mechanical assemblies. The 5-3/4 free coil count contributes to thread engagement consistency across the full installed length.

Key Features

• Tangless design eliminates tang removal after installation, reducing contamination risk in blind holes
• 304 stainless steel construction resists corrosion in wet or chemically exposed environments
• 1/4-20 UNC thread size with 0.375 inches overall length for compact thread repair applications
• 1-1/2D length-to-diameter ratio provides balanced thread engagement for the fastener size
• 5-3/4 free coils deliver consistent load distribution across the insert length
• Bright, uncoated finish maintains dimensional accuracy without added coating buildup

Compatibility

Designed as an OEM-style thread insert for parent material holes tapped to accept 1/4-20 UNC free-running wire thread inserts with a 1-1/2D engagement length.

Installation Notes

Installation requires a properly tapped insert hole using the correct HELI-COIL tap size for 1/4-20 UNC inserts at 1-1/2D. A compatible tangless installation tool is required to drive the insert to the correct depth without distorting the coils. Ensure the parent material hole is clean and free of chips before installation. Follow the insert manufacturer's installation procedure and any applicable torque specifications for the final fastener.