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Description
FINISHED THREADM20 × 1.5
VARIANT1.5×D (30 mm)
MATERIALStainless steel
SYSTEMV-Coil
M20x1.5 1.5xD thread repair insert – V-Coil DIN 8140 helical thread insert
Thread insert technical data table
| V-COIL M20x1.5 1.5×D THREAD REPAIR INSERT | |
|---|---|
| Restored thread | M20 × 1.5 |
| Thread pitch P | 1.5 mm |
| Length variant | 1.5×D |
| Insert height | 30 mm |
| Repair system | V-Coil |
| Compatible tap | M20x1.5 4H V-Coil |
| Pre-drilled hole | Ø20.5 mm |
The M20x1.5 V-Coil thread repair insert is a resilient coil made from Helicoil-type stainless steel wire that restores a damaged thread. When installed in a hole tapped with a thread repair tap, it creates a fully functional M20x1.5 thread for a standard screw. The repair requires neither a larger screw nor replacement of the component. The 1.5xD version with a height of 30 mm is selected for shallower holes in hard materials. Dimensions are specified by DIN 8140 (form A, free-running).
M20x1.5 thread repair step by step – from the hole to the completed joint
Four installation steps in the V-Coil system
Thread repair process M20 × 1.5
1Prepare the hole
diameter: Ø20.5 mm
2Tap the thread
tool: V-Coil 4H
3Screw in the insert
length: 1.5×D
✓Restore the joint
thread: M20 × 1.5
Screw in the insert using an installation tool — do not stretch it or twist it sideways.
Practical installation checks
A clean hole is essential for straightforward installation — remove chips and coolant residue. Install the insert with an installation tool, without forcing or tilting it. The top coil should sit 1/4–1/2 of a turn below the material surface. Break off the tang with a punch; always remove it from a blind hole.
Helicoil-type insert made from diamond-section wire – construction and operating principle
How the insert stays in the hole
The wire has a diamond-shaped cross section: one edge acts as a screw in relation to the hole, and the other as a nut in relation to the screw being installed. The free coil is slightly larger than the thread in the hole; as it is screwed in, it contracts elastically, then expands upon release and locks permanently in place without adhesive or additional components. Cold-rolled wire with a minimum tensile strength of 1400 MPa produces a thread that is harder and smoother than one cut directly into the material.
Why a standard M20x1.5 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. 21.95 mm in diameter — approximately 1.9 mm larger than the nominal 20 mm of the M20x1.5 thread.
It can only be prepared with a tap M20x1.5 4H V-Coil after drilling Ø20.5 mm; after repair, the screw engages a standard thread M20 × 1.5.
M20x1.5 thread repair in steel, stainless steel, cast iron and aluminum
When to choose the 1.5xD version
The insert restores threads in steel, stainless steel, cast iron, and aluminum, as well as magnesium and plastics. The length is selected according to the parent material and screw property class. The 1.5xD version is suitable for hard steel, cast iron, and shallow holes. Longer inserts are selected for soft materials and screws of property class 8.8 and higher. M20x1.5 threads are used in applications such as drain plugs in older engines. The stainless steel wire carries the load evenly, with the first thread turn taking approximately half the force.
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.
M20x1.5 1.5×D insert compatibility – required V-Coil system tools
Check before purchasing
✓Nominal thread: M20x1.5 with a pitch of 1.5 mm.
✓Tap: special M20x1.5 4H V-Coil thread repair tap.
✓Tap drill hole: Ø20.5 mm drill bit.
▲Depth: space for an insert 30 mm high and proper seating.
▲
V-Coil system requirements
Installing the insert requires an STI thread — it can only be cut with an M20x1.5 4H V-Coil thread repair tap. The free-running insert allows the screw to be screwed in and out freely; where severe vibration occurs, add threadlocker or choose a screw-locking version.
A correctly installed V-Coil M20x1.5 1.5xD thread repair insert carries loads so that the screw shank fails before the thread in the material. Plan the hole depth: the insert occupies 30 mm, or one and a half times the thread diameter (1.5 × 20 mm). In series production, the same insert serves as preventive reinforcement.
Frequently asked questions
The length is determined by 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, and 2.5–3xD is used in soft materials and with screws of property class 8.8 and higher. This insert has a length of 1.5×D (30 mm).
The top coil of the insert should sit 1/4–1/2 of a turn below the material surface. After installation, the tang is broken off with a punch. In a blind hole, the broken fragment must be removed.
Yes, insert dimensions are specified by DIN 8140 and ASME B18.29.1. This makes Helicoil, V-Coil, Recoil, and BaerCoil interchangeable. Matching size, pitch, and length are what matter.
Yes, this is a standard repair. The M18x1.5 thread is restored with an insert after tapping the hole with an STI tap. Insert system manufacturers offer dedicated oxygen sensor thread repair kits.
Product accessories
Drill 20.5 Cobalt NWKc HSSE DIN 345
Reference: 0000008560 In stock < 10 items
€35.53
€43.70 brutto
Thread repair insert M20x1.5 2xD V-Coil
Reference: 0000010715 In stock > 10 items
€1.97
€2.43 brutto
Thread repair tap M20x1.5 4H V-Coil
Reference: 0000012919 In stock > 10 items
€23.68
€29.13 brutto
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Shipping
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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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