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Description
FINISHED THREADM18 × 1.5
VARIANT2×D (36 mm)
MATERIALStainless steel
SYSTEMV-Coil
M18x1.5 2xD thread repair insert – V-Coil DIN 8140 helical thread insert
Thread insert technical data table
| V-COIL M18x1.5 2×D THREAD REPAIR INSERT | |
|---|---|
| Restored thread | M18 × 1.5 |
| Thread pitch P | 1.5 mm |
| Length variant | 2×D |
| Insert height | 36 mm |
| Repair system | V-Coil |
| Compatible tap | M18x1.5 4H V-Coil |
| Pre-drilled hole | Ø18.5 mm |
The V-Coil M18x1.5 thread repair insert is a Helicoil-type stainless steel wire coil that restores a damaged thread in metal. Installed in a hole tapped with a thread repair tap, it creates a fully functional M18x1.5 thread for a standard screw. It requires neither a larger screw nor replacement of the entire part. Select the 2xD version with a height of 36 mm for soft materials and more heavily loaded joints. The design complies with the standard DIN 8140, form A (free-running).
M18x1.5 thread repair step by step – from the hole to the completed joint
Four installation steps in the V-Coil system
Thread repair process M18 × 1.5
1Prepare the hole
diameter: Ø18.5 mm
2Tap the thread
tool: V-Coil 4H
3Screw in the insert
length: 2×D
✓Restore the joint
thread: M18 × 1.5
Screw in the insert using an installation tool — do not stretch it or twist it sideways.
Practical installation checks
After tapping, remove chips and coolant from the hole. Guide the insert with an installation tool without applying pressure — it should screw in easily. The correct depth is 1/4–1/2 of a turn below the material surface. Break off the tang with a punch, and remove the broken piece from a blind hole.
Helicoil-type insert made from diamond-section wire – construction and operating principle
How the insert stays in the hole
The insert is a resilient helix made from diamond-section wire. The outer edge of the diamond anchors in the enlarged thread in the hole, while the inner edge restores the nominal thread for the screw. In its free state, the coil is larger than the hole — installation compresses it, and upon release the coils expand and hold without adhesive. The wire has a minimum tensile strength of 1400 MPa, so the new thread is harder than the original and noticeably smoother.
Why a standard M18x1.5 tap cannot prepare the hole
A pitch of 1.5 mm means a wire thickness of approx. 0.98 mm (the 0.65 × P rule).
The installation thread for the insert is therefore approx. 19.95 mm in diameter — approximately 1.9 mm larger than the nominal 18 mm of the M18x1.5 thread.
It can only be prepared with a tap M18x1.5 4H V-Coil after drilling Ø18.5 mm; after repair, the screw engages a standard thread M18 × 1.5.
M18x1.5 thread repair in steel, stainless steel, cast iron and aluminum
When to choose the 2xD version
The insert is suitable for steel, stainless steel, cast iron, and aluminum, allowing the same solution to repair threads in different parts. Select the length according to the parent material and the load on the screw. The 2xD version is a general-purpose choice for aluminum and typical joints. Use the shorter 1.5xD insert in steel and shallow holes, and a longer one in soft material and with screws of property class 8.8 or higher. Typical applications include restoring an M18x1.5 oxygen sensor thread in an exhaust manifold. The force distribution is not uniform — the first thread turn carries approximately half the load.
Thread strength: how much load each turn carries
| Thread turn | Standard thread (without an insert) | Thread with a V-Coil insert |
|---|---|---|
| 1 (first from the screw head) | 50% | 30% |
| 2 | 25% | 22% |
| 3 | 12% | 17% |
| 4 | 6% | 13% |
| 5 | 3% | 10% |
| 6 | 2% | 8% |
How to read the table: when the screw is tightened, each thread turn carries part of its load. In a standard thread, the first turn carries as much as 50% of the load — and it strips first. With an insert, the same turn carries only 30% because the load is distributed over the entire thread length. Catalog data from wire thread insert manufacturers.
M18x1.5 2×D insert compatibility – required V-Coil system tools
Check before purchasing
✓Nominal thread: M18x1.5 with a pitch of 1.5 mm.
✓Tap: special M18x1.5 4H V-Coil thread repair tap.
✓Tap drill hole: Ø18.5 mm drill bit.
▲Depth: space for an insert 36 mm high and proper seating.
▲
What to remember before repair
The insert requires an STI thread cut with a V-Coil system thread repair tap — a standard M18x1.5 tap cuts a smaller thread in which the insert will not seat. The free-running version does not lock the screw: use threadlocker or a screw-locking insert for joints exposed to vibration.
A correctly installed V-Coil M18x1.5 2xD thread repair insert carries loads so that the screw shank fails before the thread in the material. Plan the hole depth: the insert occupies 36 mm, or twice the thread diameter (2 × 18 mm). In series production, the same insert serves as preventive reinforcement.
Frequently asked questions
Length depends on the parent material and screw property class — the weaker the material and the stronger the screw, the longer the insert. The 1.5xD version is suitable for steel, cast iron, and shallow holes; 2xD is standard for aluminum, while 2.5–3xD is suitable for soft materials and screws of property class 8.8+. This insert is 2×D with a height of 36 mm.
No. The coil is larger than the tapped hole and locks itself permanently in place, so it holds without adhesive. Threadlocker is used only under severe vibration; a screw-locking insert to DIN 8140 form B is an alternative.
No, the insert requires a larger STI thread with a diameter of approximately 19.95 mm. A standard M18x1.5 thread is only 18 mm in diameter, making it approximately 1.9 mm too small. Drill the hole to Ø18.5 mm and tap it with an M18x1.5 4H V-Coil tap.
Yes. The M18x1.5 sensor thread is restored with an insert after tapping the hole with an STI tap, allowing the manifold to remain in place. This is a standard procedure, and dedicated sensor thread repair kits are catalog items offered by insert system manufacturers.
Product accessories
Thread repair tap M18x1.5 4H V-Coil
Reference: 0000008300 In stock > 10 items
€14.47
€17.80 brutto
HSSE 18.5 cobalt metal drill bit DIN 338
Reference: 13299 In stock > 10 items
€18.42
€22.66 brutto
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| Courier GLS | Przelew24 / Prepayment | 14,76 zł gross | Delivery time 1 working day |
| Courier GLS | Cash on delivery | 17,26 zł gross | Lead time 1 working day |
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