- 98% satisfied customers
- 72h delivery
- 30 dni na zwrot
Description
FINISHED THREADM8 × 1
VARIANT2.5×D (20 mm)
MATERIALStainless steel
SYSTEMV-Coil
M8x1 2.5xD thread repair insert – V-Coil DIN 8140 helical thread insert
Thread insert technical data table
| V-COIL M8x1 2.5×D THREAD REPAIR INSERT | |
|---|---|
| Restored thread | M8 × 1 |
| Thread pitch P | 1 mm |
| Length variant | 2.5×D |
| Insert height | 20 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 fine thread. 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. The variant 2.5xD with a height of 20 mm is selected for soft materials and more heavily loaded joints. The design complies with DIN 8140 form A (free-running).
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: 2.5×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
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 wire has a diamond-shaped cross section, so it works on both sides simultaneously: the outer edge engages the thread in the hole, while the inner edge forms a new thread for the screw. Before installation, the coil is slightly larger than the hole. As it is screwed in, the coils compress; when the tool is released, they expand and lock permanently in place — without adhesive. The wire has a minimum tensile strength of 1400 MPa — the new thread is harder and smoother than a thread cut directly into the material.
Why a standard M8x1 tap cannot prepare the hole
A pitch of 1 mm means a wire thickness of approx. 0.65 mm (the 0.65 × P rule).
The installation thread for the insert is therefore approx. 9.3 mm in diameter — approximately 1.3 mm larger than the nominal 8 mm of the M8x1 thread.
It can only be prepared with a tap M8x1 4H V-Coil after drilling Ø8.3 mm; after repair, the screw engages a standard thread M8 × 1.
M8x1 thread repair in steel, stainless steel, cast iron and aluminum
When to choose the 2.5xD version
The insert restores an M8x1 thread in steel, stainless steel, cast iron and aluminum, as well as magnesium and plastics. Stainless steel wire with a minimum tensile strength of 1400 MPa provides a hard, durable load-bearing surface. The length is selected according to the parent material and screw property class. The variant 2.5xD is suitable for soft materials and screws of property class 8.8 or higher. A shorter insert is selected for shallow holes and steel, and a longer one for soft materials. Applications include restoring banjo bolt threads in brake lines connected to motorcycle master cylinders. Load distribution is critical here because 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.
M8x1 2.5×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 20 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.
After installation of the V-Coil M8x1 2.5xD thread repair insert, the screw determines the joint's load limit, rather than the thread in the part. The hole must accommodate the 20 mm insert (2.5 × 8 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
The length is selected according to the parent material and screw property class. The 1.5xD variant is suitable for steel, cast iron and shallow holes. The 2xD variant is standard for aluminum, and 2.5–3xD is for soft materials and screws of property class 8.8 or higher. This insert has a length of 2.5xD, equivalent to 20 mm.
No. The coil is larger than the thread in the hole and locks permanently in place without anything extra. Threadlocker is used only under severe vibration, while more demanding applications call for a screw-locking insert in form B of the standard DIN 8140.
No. The insert requires an STI thread with a diameter of approximately 9.3 mm, while a standard M8x1 thread is 8 mm, making it approximately 1.3 mm too small. Drill the hole to Ø8.3 mm and tap it with an M8x1 4H V-Coil tap.
The insert restores the mechanical M8x1 thread in the hole and carries the joint load. Banjo connections and bleeder screws are sealed by the seating surface or washer, not by the thread itself. After repair, inspect the seating surfaces and use new sealing washers.
Product accessories
Thread repair insert M8x1 1.5xD V-Coil
Reference: 0000005774 In stock < 10 items
€0.37
€0.45 brutto
Reviews
No customer reviews for the moment.
Shipping
All orders are delivered by courier company GLS. For orders exceeding 369 PLN gross shipping is FREE
| 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 |
Recommended for you
This website uses its own and third-party cookies to improve our services and show you advertising related to your preferences by analyzing your browsing habits. To give your consent to its use, press the Accept button.
Cookie preferences
Functional cookiesTechnical
Functional cookies are strictly necessary to provide the services of the shop, as well as for its proper functioning, so it is not possible to refuse their use. They allow the user to browse through our website and use the different options or services that exist on it.
Advertising Cookies
These are cookies that collect information about the advertisements shown to users of the website. They can be anonymous, if they only collect information about the advertising spaces shown without identifying the user, or personalised, if they collect personal information about the user of the shop by a third party, for the personalisation of these advertising spaces.
Analytics cookies
Collect information about the user's browsing experience in the shop, usually anonymously, although sometimes they also allow the user to be uniquely and unequivocally identified in order to obtain reports on the user's interests in the products or services offered by the shop.