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Description
FINISHED THREADM20 × 1.5
VARIANT2×D (40 mm)
MATERIALStainless steel
SYSTEMV-Coil
M20x1.5 2xD thread repair insert – V-Coil DIN 8140 helical thread insert
Thread insert technical data table
| V-COIL M20x1.5 2×D THREAD REPAIR INSERT | |
|---|---|
| Restored thread | M20 × 1.5 |
| Thread pitch P | 1.5 mm |
| Length variant | 2×D |
| Insert height | 40 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. When installed in a hole tapped with a thread repair tap, it restores a fully functional M20x1.5 thread for a standard screw. The repair requires neither a larger screw nor replacement of the entire component. The 2xD version with a height of 40 mm is selected for standard applications and harder materials. The design conforming to DIN 8140 form A provides a free-running thread.
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: 2×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
Before installation, clean chips and coolant residue out of the hole. Screw in the insert with an installation tool, keeping it straight and using no force. A properly seated insert sits 1/4–1/2 of a turn below the surface. Finally, break off the tang (the crosspiece at the bottom of the insert) with a punch; if the hole is blind, remove the broken piece so that it does not obstruct the screw.
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 an STI tap is required instead of a standard M20x1.5 tap
The wire thickness is determined by the thread pitch: 0.65 × 1.5 mm ≈ 0.98 mm.
The thread for the insert is enlarged to accommodate the wire on both sides of the profile — its diameter is approx. 21.95 mm compared with 20 mm for a standard M20x1.5 thread.
It can only be cut with a thread repair tap M20x1.5 4H V-Coil in a hole drilled to Ø20.5 mm; after the insert is installed, the hole returns to the nominal thread M20 × 1.5.
M20x1.5 thread repair in steel, stainless steel, cast iron and aluminum
When to choose the 2xD version
The same 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 2xD version is a practical standard for most joints. Choose a shorter insert for a shallow hole and hard steel, and a longer insert for soft materials and screws of property class 8.8 or higher. M20x1.5 threads are used in applications such as drain plugs in older engines. After installation the first thread carries approximately half the axial 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 2×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 40 mm high and proper seating.
▲
Application limitations
The thread for the insert must be cut with an M20x1.5 4H V-Coil STI tap — the nominal M20x1.5 thread is too small for the insert to anchor in it. The free-running version does not prevent the screw from loosening: threadlocker or a screw-locking insert helps under vibration.
The M20x1.5 2xD V-Coil thread repair insert creates a joint in which the weakest point is the bolt, rather than the thread in the repaired part. Allow for the depth: 40 mm equals two thread diameters (2 × 20 mm) — this is the space the hole must provide. The same insert is also used to reinforce threads in series production.
Frequently asked questions
The length is selected according to the parent material and screw property class: the weaker the material and the stronger the screw, the longer the insert. For steel, cast iron, and shallow holes, 1.5xD is sufficient, while 2xD is standard for aluminum. Soft materials and screws of property class 8.8 or higher require 2.5–3xD, and the insert shown has a length of 2×D (40 mm).
The top coil of the insert should sit from 1/4 to 1/2 of a turn below the material surface. After installation, break off the tang with a punch. In a blind hole, then remove the broken fragment from the bottom of the hole.
Yes, because insert dimensions are specified by DIN 8140, supplemented by ASME B18.29.1. This keeps Helicoil, V-Coil, Recoil, and BaerCoil products interchangeable. Matching insert size, pitch, and length are what matter.
Yes, this is a standard repair that does not require removing the manifold. The sensor's 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 as catalog items.
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 1.5xD V-Coil
Reference: 0000010797 In stock < 10 items
€2.08
€2.56 brutto
Thread repair tap M20x1.5 4H V-Coil
Reference: 0000012919 In stock > 10 items
€23.68
€29.13 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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