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Description
FINISHED THREADM8 × 1
VARIANT2×D (16 mm)
MATERIALStainless steel
SYSTEMV-Coil
M8x1 2xD thread repair insert – V-Coil DIN 8140 helical thread insert
Thread insert technical data table
| V-COIL M8x1 2×D THREAD REPAIR INSERT | |
|---|---|
| Restored thread | M8 × 1 |
| Thread pitch P | 1 mm |
| Length variant | 2×D |
| Insert height | 16 mm |
| Repair system | V-Coil |
| Compatible tap | M8x1 4H V-Coil |
| Pre-drilled hole | Ø8.3 mm |
The V-Coil M8x1 thread repair insert is a Helicoil-type stainless steel wire coil that restores a stripped internal thread in metal. Installed in a hole tapped with a thread repair tap, it creates a fully functional M8x1 thread for a standard screw. The repair requires neither a larger screw nor replacement of the entire part. Select the 2xD version with a height of 16 mm for standard holes and holes in soft material where longer thread engagement is needed. The dimensions comply with DIN 8140 form A, the free-running version.
M8x1 thread repair step by step – from the hole to the completed joint
Four installation steps in the V-Coil system
Thread repair process M8 × 1
1Prepare the hole
diameter: Ø8.3 mm
2Tap the thread
tool: V-Coil 4H
3Screw in the insert
length: 2×D
✓Restore the joint
thread: M8 × 1
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 a standard M8x1 tap will not work here
The insert wire has a thickness of approx. 0.65 mm (calculated from the thread pitch: 0.65 × 1 mm).
The thread for the insert must accommodate the wire on both sides of the profile, so its diameter is approx. 9.3 mm — approximately 1.3 mm larger than a standard M8x1 thread (8 mm).
This enlarged thread can only be cut with a thread repair tap M8x1 4H V-Coil, after drilling the hole Ø8.3 mm. Once the insert is screwed in, the screw again engages a standard thread M8 × 1.
M8x1 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 across a range of industries. The parent material and screw property class determine the length. The 2xD version is a standard choice when the parent material is soft or the screw is stronger. Select a shorter insert for a shallow hole in steel and a longer one for soft material and screws of property class 8.8 and higher. The M8x1 thread is used, for example, in brake line banjo bolts at motorcycle master cylinders. After installation the first thread carries approximately half the force, and the table below shows the load distribution.
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.
M8x1 2×D insert compatibility – required V-Coil system tools
Check before purchasing
✓Nominal thread: M8x1 with a pitch of 1 mm.
✓Tap: special M8x1 4H V-Coil thread repair tap.
✓Tap drill hole: Ø8.3 mm drill bit.
▲Depth: space for an insert 16 mm high and proper seating.
▲
V-Coil system requirements
Installing the insert requires an STI thread — it can only be cut with an M8x1 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.
The M8x1 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: 16 mm equals two thread diameters (2 × 8 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 parent material and screw property class are the deciding factors — 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 such as magnesium or plastics and screws of property class 8.8 and higher. This insert has a length of 2×D, equivalent to 16 mm.
No — the coil is larger than the tapped hole and locks itself permanently in place. Use threadlocker only under severe vibration, or select a DIN 8140 form B screw-locking insert.
Yes — insert dimensions are specified by DIN 8140 and ASME B18.29.1, so Helicoil, V-Coil, Recoil, and BaerCoil versions are interchangeable. Size, pitch, and length matter, not the manufacturer.
Yes, the insert restores the mechanical M8x1 internal thread. Banjo connections and bleed screws are sealed by a sealing face or washer, not by the thread itself. After repair, inspect the sealing face and install new washers.
Product accessories
Thread repair insert M8x1 1.5xD V-Coil
Reference: 0000005774 In stock < 10 items
€0.37
€0.45 brutto
Thread repair insert M8x1 2.5xD V-Coil
Reference: 0000006044 In stock > 10 items
€0.53
€0.65 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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