Thread repair kits: complete for one thread size
A thread repair kit contains everything you need for one thread size: the STI tap for the tapped hole, the installation tool, the tang breaker and a supply of V-COIL wire thread inserts in 1.5 D. Up to M 12 the matching twist drill is included. VÖLKEL supplies 150 kits for metric coarse and fine threads from M 2 to M 64 and for UNC, UNF, BSW, BSF and G (BSP).
How the repair works
- Drill: drill out the damaged thread with the twist drill from the kit. For spark plug threads this step is omitted; there a combined drilling and tapping tool cuts.
- Check: confirm that tap and screw have the same thread and pitch.
- Tap: cut the tapped hole with the STI tap, using cutting oil.
- Fit the insert: place the insert on the installation tool, the drive tang sits in the notch. Screw in with light pressure in the thread direction, never against it.
- Break the tang: remove the tool and break off the drive tang with the tang breaker; for large sizes use pointed pliers.
Thanks to the close tolerances of the spring thread the result is a thread that is often stronger than the original. Step by step with pictures in Loosening and repairing a seized thread.
Which kit do you need?
The kit follows thread and pitch, for example M 10 x 1.5 for coarse or M 10 x 1.25 for fine thread. For the cordless drill the kits come as V-COIL rapid with HexTap tap, for spark plugs, oil drain plugs and lambda sensors as V-COIL automotive, for tangless inserts as V-COIL notch. Several sizes in one case are the thread repair workshop kits. Replacement inserts, also in 1.0 D, 2.0 D, 2.5 D and 3.0 D, are under wire thread inserts.
