General Thread Repair

Fig 1: 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.

Fig 2: Drilling & Tapping Threads
Courtesy of GENERAL MOTORS COMPANY
WARNING:

Refer to Safety Glasses Warning .

NOTE:
• The use of a cutting type fluid, WD 40®, or equivalent, is recommended when performing the drilling, counterboring, and tapping procedures. Refer to Adhesives, Fluids, Lubricants, and Sealers  for recommended fluid.
• 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.
1. Drill out the threads of the damaged hole (1).
   • 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.
Fig 3: Tool Used To Counterbore The Hole
Courtesy of GENERAL MOTORS COMPANY
3. Counterbore the hole to the full depth permitted by the tool (1).
4. Using compressed air, clean out any chips.
Fig 4: Drilling & Tapping Threads
Courtesy of GENERAL MOTORS COMPANY
5. Using a tap wrench (2), tap the threads of the drilled hole.
   • 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.
7. Spray cleaner into the hole. Refer to Adhesives, Fluids, Lubricants, and Sealers  for recommended cleaner.
8. Using compressed air, clean any cutting oil and chips out of the hole.
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.

9. Lubricate the threads of the installer tool (2) with the driver oil (1).
Fig 6: Bushing Type Insert
Courtesy of GENERAL MOTORS COMPANY
10. Install the insert (2) onto the driver tool (1).
Fig 7: Applying Threadlock To Insert
Courtesy of GENERAL MOTORS COMPANY
11. Apply threadlock LOCTITE™ 277, J 42385-109 (1), or equivalent, to the insert OD threads (2).
Fig 8: Insert In Tapped Bolt Hole
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 9: Bushing Type Insert & Base Material
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).