Heli-Coil 5528-4 Thread Repair Kit, 1/4-28 UNF, 0.37" Insert Length, 17/64" Drill Size, Kit with 12 Inserts

Heli-Coil 5528-4 Thread Repair Kit, 1/4-28 UNF, 0.37" Insert Length, 17/64" Drill Size, Kit with 12 Inserts

• Heli-Coil 5528-4 is a thread repair kit used to restore damaged 1/4-28 UNF internal threads back to the original size. The kit includes 12 Heli-Coil inserts plus the matching Heli-Coil tap and installation tool for installing the inserts after drilling and tapping the prepared hole.
• Features:
  • Thread size 1/4-28 UNF is intended for repairing stripped or worn internal threads of the same size.
  • 12 insert quantity supports multiple repairs without purchasing additional inserts.
  • Includes the correct Heli-Coil tap and installation tool to support proper insert installation.
  • Insert length 0.37" supports standard length repairs for 1/4-28 UNF thread applications.
  • System Compatibility or Application: Designed to repair 1/4-28 UNF tapped holes by installing Heli-Coil thread inserts, not a replacement part for another SKU.
• Includes:
  • Heli-Coil thread inserts, 1/4-28 UNF, 0.37" length (12 pieces)
  • Heli-Coil tap, 1/4-28 UNF STI
  • Heli-Coil installation tool
  • Instruction sheet
• Specifications:
  • Manufacturer: Heli-Coil
  • Part Number: 5528-4
  • MPN: 5528-4
  • UPC: 025964110206
  • Category: Fasteners and Thread Repair
  • Subcategory: Thread Repair Inserts and Kits
  • Product Type / Function: Thread repair kit for restoring internal threads
  • Thread Size: 1/4-28 UNF
  • Insert Quantity: 12 identical inserts
  • Insert Length: 0.37"
  • Required Drill Size: 17/64"
  • System Compatibility or Application: Repairs 1/4-28 UNF tapped holes by installing Heli-Coil inserts after drilling to 17/64" and tapping with the included STI tap
• The Thread Repair Kit can also be referred to as a 1/4-28 UNF thread repair kit, wire thread insert kit, Heli-Coil insert kit, 1/4-28 thread insert kit, and stripped thread repair kit.

Heli-Coil is a thread repair and fastening brand known for wire thread inserts and related installation tools used to restore or reinforce tapped threads. The product line is widely used in industrial maintenance, automotive service, and general mechanical repair applications.

Q: What thread size does this kit repair?
A: It is designed to repair internal threads to 1/4-28 UNF.

Q: What drill size is required before tapping?
A: The required drill size is 17/64".

Q: How many inserts are included?
A: The kit includes 12 inserts.

Q: Does the kit include the installation tooling?
A: Yes, it includes a Heli-Coil tap and an installation tool for installing the inserts.