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Description
FINISHED THREADM14 × 1.25
VARIANT2×D (28 mm)
MATERIALStainless steel
SYSTEMV-Coil
M14x1.25 2xD thread repair insert – V-Coil DIN 8140 helical thread insert
Thread insert technical data table
| V-COIL M14x1.25 2×D THREAD REPAIR INSERT | |
|---|---|
| Restored thread | M14 × 1.25 |
| Thread pitch P | 1.25 mm |
| Length variant | 2×D |
| Insert height | 28 mm |
| Repair system | V-Coil |
| Compatible tap | M14x1.25 4H V-Coil |
| Pre-drilled hole | Ø14.3 mm |
The V-Coil M14x1.25 thread repair insert is a resilient Helicoil-type stainless steel wire coil. Installed in a hole tapped with a thread repair tap, it restores a fully functional M14x1.25 thread for a standard screw. It requires neither a larger screw nor replacement of the entire part. The 2xD version with a height of 28 mm is selected for holes in softer material and for stronger screws. Construction to DIN 8140 form A ensures free-running screw installation.
M14x1.25 thread repair step by step – from the hole to the completed joint
Four installation steps in the V-Coil system
Thread repair process M14 × 1.25
1Prepare the hole
diameter: Ø14.3 mm
2Tap the thread
tool: V-Coil 4H
3Screw in the insert
length: 2×D
✓Restore the joint
thread: M14 × 1.25
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 M14x1.25 tap will not work here
The insert wire has a thickness of approx. 0.81 mm (calculated from the thread pitch: 0.65 × 1.25 mm).
The thread for the insert must accommodate the wire on both sides of the profile, so its diameter is approx. 15.62 mm — approximately 1.6 mm larger than a standard M14x1.25 thread (14 mm).
This enlarged thread can only be cut with a thread repair tap M14x1.25 4H V-Coil, after drilling the hole Ø14.3 mm. Once the insert is screwed in, the screw again engages a standard thread M14 × 1.25.
M14x1.25 thread repair in steel, stainless steel, cast iron and aluminum
When to choose the 2xD version
The insert restores threads in steel, stainless steel, cast iron, and aluminum, as well as magnesium and plastics. Select the length according to the parent material and screw property class. The 2xD (28 mm) version is standard for aluminum and typical loads. In a shallow hole and hard steel, 1.5xD is sufficient, while 2.5xD is better suited to soft material and screws of property class 8.8 or higher. This addresses, among other applications, the most common automotive thread repair — a stripped M14x1.25 spark plug thread in an aluminum cylinder head. After installation, the first thread turn carries approximately half the force, as shown in the load distribution table.
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.
M14x1.25 2×D insert compatibility – required V-Coil system tools
Check before purchasing
✓Nominal thread: M14x1.25 with a pitch of 1.25 mm.
✓Tap: special M14x1.25 4H V-Coil thread repair tap.
✓Tap drill hole: Ø14.3 mm drill bit.
▲Depth: space for an insert 28 mm high and proper seating.
▲
V-Coil system requirements
Installing the insert requires an STI thread — it can only be cut with an M14x1.25 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.
After installation of the V-Coil M14x1.25 2xD thread repair insert, the screw determines the joint's load limit, rather than the thread in the part. The hole must accommodate the 28 mm insert (2 × 14 mm) along with the proper recess below the surface. In addition to repairs, the insert is suitable for reinforcing threads during manufacturing.
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 used in soft materials and with screws of property class 8.8 or higher. This insert has a length of 2xD (28 mm).
Position the top turn of the insert 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, the broken fragment must be removed before installing the screw.
Yes, because insert dimensions are specified by DIN 8140 and ASME B18.29.1. This makes Helicoil, V-Coil, Recoil, and BaerCoil inserts interchangeable. Matching size, pitch, and length are what matter.
Aluminum has low shear strength, and in a thread cut directly into the material, the first turn carries approximately 50% of the total force. In addition, the spark plug is removed from its threaded hole at every service, often while the engine is hot. The insert distributes the load more evenly across successive thread turns.
Product accessories
Thread repair tap M14x1.25 4H V-Coil
Reference: 0000006028 In stock > 10 items
€19.47
€23.95 brutto
Thread repair insert M14x1.25 2.5xD V-Coil
Reference: 0000006046 In stock > 10 items
€1.05
€1.29 brutto
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| Courier GLS | Cash on delivery | 17,26 zł gross | Lead time 1 working day |
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