Thread Repair Kits for Stripped Thread Recovery
Restore stripped, worn or damaged threads to original size — inserts, STI taps, tools and gauges engineered to work together. For aluminum, cast iron, engine blocks, gearboxes and field service, from the factory that makes the inserts.
A thread repair kit restores a stripped or worn threaded hole to its original size and full strength: drill the hole to size, tap it with the included STI tap, install a thread insert, and the standard thread is back — no oversize bolts, no scrapping the part. Ankolam kits combine factory-made inserts with matching taps, tools and gauges from one engineering source.
When Threads Fail — and How Repair Beats Replacement
Stripped threads happen where soft parent material meets repeated assembly: aluminum housings, engine blocks and heads, gearbox casings, pump bodies. The traditional fixes are all expensive — re-drill to a larger bolt (weakens the part, changes the fastener BOM) or scrap the component. A repair insert returns the hole to original specification with a thread that is typically stronger than the parent thread, because bolt load transfers to the insert’s steel coils or body.
| Situation | Recommended Repair | Why |
|---|---|---|
| Worn aluminum housing thread | Wire thread insert kit | Load-spreading coil suits soft alloys |
| Stripped high-torque boss | Key locking insert kit | Solid body + keys take full bolt torque |
| Spark plug / oil drain threads | Repair insert kit for that size | Restore original size, no machining changes |
| FOD-sensitive or frequent service | Tangless insert kit | No tang break-off; clean removal for rework |
| Field / maintenance crew use | Complete kit in case | Drill, tap, inserts, tools, gauges — one box |
How a Kit-Based Repair Works — Four Steps
| Step | Action | Key Control |
|---|---|---|
| 1 · Drill | Drill out the damaged thread to the kit’s specified diameter; chamfer the hole mouth | Use the listed drill size only — oversize holes reduce coil engagement |
| 2 · Tap | Tap the hole with the kit’s STI tap | Lubricate; keep the tap square to the hole |
| 3 · Install | Wind the insert in with the installation tool until it sits 0.2 mm below the surface | Start square in the first 1–2 threads; never reverse mid-installation |
| 4 · Verify | Break off and remove the tang (tanged type); check with GO/NO-GO gauge if fitted | Recover the tang — FOD discipline |
Matched tooling matters: kit taps are ground for the insert’s thread class, and the gauges verify what the bolt will actually feel. All items are listed in installation tools.
What Ships in an Ankolam Repair Kit
| Component | Included | Notes |
|---|---|---|
| Thread inserts | Per size and quantity spec | Wire / tangless / key locking per application |
| STI tap | 1 per size | Cutting or forming type matched to kit |
| Drill reference | Size chart | Exact Ø per size and parent material |
| Installation tool | 1 per size | Mandrel for coils; driver for self-tapping |
| Tang break tool / extractor | 1 | Tanged coils; extractor removes mis-installed inserts without parent damage |
| Thread gauge | Optional GO/NO-GO | Red ring marks the NO-GO end |
| Case | Organizer box | Field-service ready |
Kit configurations are quoted per requirement — tell us the thread sizes, parent material and crew type (production line or field service) and we assemble the kit list.
Why Buy Repair Kits from the Insert Factory
One Engineering Source
Inserts, taps and tools are made and matched by the same factory — no cross-brand tolerance stacking between insert and tooling.
Quality Control on Every Lot
Kit inserts pass the same dimensional inspection as production volume — a repair is only as good as the insert in it.
Volume Pricing on Consumables
Refill inserts and taps in bulk — kits for the crews, bulk packs for the stores.
Fast Restock
Semi-finished stock on common sizes shortens standard delivery by about half, keeping maintenance lines running.
Repair Economics in Practice
In our engineering cases, insert-based repair kept aluminum airframe structures and titanium brackets in service instead of replacing them — the same physics that make repair kits standard issue in engine shops: a casing saved is a casing you didn’t buy. See case studies for the application stories.
Thread Repair FAQ
Can a repaired thread be as strong as the original?
Stronger, typically. The bolt now engages a hardened steel insert that distributes load along its full length — in aluminum, thread loading capacity of 3–4× the parent thread is routine.
Can the repair be undone or re-done?
Yes. A mis-installed insert extracts with the removal tool without damaging the parent thread, and a worn insert can be replaced in minutes.
Which kit do I need for a spark plug hole?
Spark-plug sizes are a classic repair application — send us the plug thread designation and we confirm the kit contents.
Do you supply kits for inch sizes?
Yes — UNC/UNF kits alongside metric, with MS-series inserts stocked in 303 stainless for inch applications.
Request a Thread Repair Kit Quote
List your thread sizes and application — kit configuration and pricing back within one business day.