BILITOOLS Helicoil Thread Repair Kit Metric M5–M12 — Stainless Inserts & HSS Tools, Case

If a bolt hole in an engine mount, gearbox housing, or plumbing fitting has been damaged, this kit supplies the drills, taps, installation tools and stainless inserts needed to rebuild the thread to factory or stronger specification. The set combines hardened twist drills with taps and 304 stainless helicoil-style inserts sized for the most common metric fasteners, packaged in a molded carrying case so you can tackle repairs on the bench or at the job site.

How do I use this kit to repair a stripped thread?

Repairing a thread is a three-step process: drill to the specified oversized pilot, cut the new female thread using the matched tap, then insert the coiled stainless insert so it locks into the fresh thread. The kit includes break-off tang tools to seat and remove the tang once the insert is installed.

• Drill with the supplied 4241 HSS twist drill sized for each insert.
• Tap the hole using the matching 4241 HSS tap included.
• Use the break pin tool to wind the 304 stainless insert into place, then break off the tang.

Which fastener sizes and quantities are included?

The kit covers the most frequently used metric sizes from M5 through M12, with higher quantities of smaller sizes for common repairs. Inserts are stainless steel for corrosion resistance and higher torque capacity than many base materials.

• M5 x 0.8: 25 inserts
• M6 x 1.0: 25 inserts
• M8 x 1.25: 25 inserts
• M10 x 1.5: 25 inserts
• M12 x 1.75: 10 inserts
• Includes 5 matching HSS drills, 5 HSS taps and 5 break-pin tools for the set of sizes

What materials and applications is the kit suitable for?

These stainless inserts and HSS cutting tools work in a broad range of substrates: ferrous and non-ferrous metals, composites and many polymers. That versatility makes the kit useful for automotive, motorcycle, marine, construction and household plumbing repairs.

• 304 stainless inserts resist corrosion where exposure to moisture or salty air is expected.
• HSS 4241 drills and taps provide strong cutting performance through metals and composites.
• Ideal for engine components, transmission housings, motor mounts, valve bodies and threaded fittings.

What does the case and tooling offer for workshop efficiency?

All components are arranged in a blow-molded case so you can quickly identify the correct drill, tap and insert size. Organized tooling reduces downtime and protects small parts during transport or storage.

• Clearly labeled cavities for drills, taps, inserts and break-pin tools.
• Compact case fits on a bench, in a van, or in a toolbox drawer.
• Durable molded plastic protects HSS tools and stainless inserts from damage.

Who is this for? The BILITOOLS Helicoil Thread Repair Kit Metric is designed for professional mechanics, maintenance technicians, DIY enthusiasts and tradespeople who need a reliable, repeatable way to restore stripped or undersized internal threads. If you repair engines, gearboxes, plumbing fixtures, brackets or any component that relies on threaded fasteners, this kit supplies the matched drill, tap, install tool and corrosion-resistant inserts to complete the job quickly and correctly.