General Thread Repair

Fig 1: View Of Bushing Type Insert & Base Material

Courtesy of GENERAL MOTORS COMPANY

The thread repair process involves a solid, thin walled, self-locking, carbon steel, bushing type insert (1). During the bushing installation process, the driver tool expands the bottom external threads of the insert into the base material (2). This action mechanically locks the insert in place. Also, when installed to the proper depth, the flange of the insert will be seated against the counterbore of the repaired hole.

1. Drill out the threads of the damaged hole (1).
   Fig 2: Drilling & Tapping Threads

   Courtesy of GENERAL MOTORS COMPANY
   NOTE:

   The use of a cutting fluid, WD 40® or equivalent, is recommended when performing the drilling, counterboring and tapping procedures. Refer to Adhesives, Fluids, Lubricants and Sealers .

   Driver oil MUST be used on the installer driver tool.

   The tool kits are designed for use with either a suitable tap wrench or drill motor.

   • M6 inserts require a minimum drill depth of 15 mm (0.59 in).
   • M8 inserts require a minimum drill depth of 20 mm (0.79 in).
   • M10 inserts require a minimum drill depth of 23.5 mm (0.93 in).
2. Using compressed air, clean out any chips.
   WARNING: Refer to Safety Glasses and Compressed Air Warning .
3. Counterbore the hole to the full depth permitted by the tool (1).
   Fig 3: Identifying Tool Used To Counterbore The Hole

   Courtesy of GENERAL MOTORS COMPANY
4. Using compressed air, clean out any chips.
5. Using a tap wrench (2), tap the threads of the drilled hole.
   Fig 4: Drilling & Tapping Threads

   Courtesy of GENERAL MOTORS COMPANY
   • M6 inserts require a minimum tap depth of 15 mm (0.59 in).
   • M8 inserts require a minimum tap depth of 20 mm (0.79 in).
   • M10 inserts require a minimum tap depth of 23.5 mm (0.93 in).
6. Using compressed air, clean out any chips.
   WARNING: Refer to Safety Glasses and Compressed Air Warning .
   WARNING: Refer to Cleaning Solvent Warning .
7. Spray cleaner into the hole. Refer to Adhesives, Fluids, Lubricants and Sealers .
8. Using compressed air, clean any cutting oil and chips out of the hole.
9. Lubricate the threads of the installer tool (2) with the driver oil (1).
   Fig 5: Lubricating Installer Tool Using Driver Oil

   Courtesy of GENERAL MOTORS COMPANY
   NOTE: Do not allow oil or other foreign material to contact the outside diameter (OD) of the insert.
10. Install the insert (2) onto the driver tool (1).
    Fig 6: View of Bushing Type Insert

    Courtesy of GENERAL MOTORS COMPANY
11. Apply threadlock LOCTITE™ 277, EN 42385 - 109 (1)  loctite or equivalent to the insert OD threads (2).
    Fig 7: Applying Threadlock To Insert

    Courtesy of GENERAL MOTORS COMPANY
12. Install the insert (2) into the hole.

    Install the insert until the flange of the insert contacts the counterbored surface. Continue to rotate the installer tool (1) through the insert.

    The installer tool will tighten up before screwing completely through the insert. This is acceptable. You are forming the bottom threads of the insert and mechanically locking the insert to the base material threads.

    Fig 8: View Of Insert In Tapped Bolt Hole

    Courtesy of GENERAL MOTORS COMPANY
13. Inspect the insert for proper installation into the hole.

    A properly installed insert (1) will be either flush or slightly below flush with the surface of the base material (2).

    Fig 9: View Of Bushing Type Insert & Base Material

    Courtesy of GENERAL MOTORS COMPANY