General Thread Repair

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 EN-42385  Driver 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. Thread Repair Specifications

1. Courtesy of GENERAL MOTORS COMPANY

   NOTE:

   • The use of a cutting type fluid or equivalent, is recommended when performing the drilling, counterboring, and tapping procedures. Adhesives, Fluids, Lubricants, and Sealers
   • Driver oil MUST be used on the installer driver tool. Adhesives, Fluids, Lubricants, and Sealers
   • The tool kits are designed for use with either a suitable tap wrench or drill motor.

   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.

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   Counterbore the hole to the full depth permitted by EN-42385  Counterbore (1). Thread Repair Specifications

4. Using compressed air, clean out any chips.

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   Using a EN-42385  Tap (2), tap the threads of the drilled hole. Thread Repair Specifications

   • 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. Adhesives, Fluids, Lubricants, and Sealers
8. Using compressed air, clean any cutting oil and chips out of the hole.

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   NOTE:

   Do not allow oil or other foreign material to contact the outside diameter (OD) of the insert.

   Lubricate the threads of the EN-42385  Driver (2) with the driver oil (1). Thread Repair Specifications

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    Install the insert (2) onto the EN-42385  Driver (1). Thread Repair Specifications

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    Apply threadlock to the insert OD threads (2). Adhesives, Fluids, Lubricants, and Sealers

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    NOTE:

    The EN-42385  Driver 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. Thread Repair Specifications

    Install the insert (2) into the hole until the flange of the insert contacts the counterbored surface. Continue to rotate the EN-42385  Driver (1) through the insert. Thread Repair Specifications

13. Courtesy of GENERAL MOTORS COMPANY

    NOTE:

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

    Inspect the insert for proper installation into the hole.