- 98% satisfied customers
- 72h delivery
- 30 dni na zwrot
Description
FINISHED THREADM12 × 1.75
VARIANT3×D (36 mm)
MATERIALStainless steel
SYSTEMV-Coil
M12 3xD thread repair insert – V-Coil DIN 8140 helical thread insert
Thread insert technical data table
| V-COIL M12 3×D THREAD REPAIR INSERT | |
|---|---|
| Restored thread | M12 × 1.75 |
| Thread pitch P | 1.75 mm |
| Length variant | 3×D |
| Insert height | 36 mm |
| Repair system | V-Coil |
| Compatible tap | M12 4H V-Coil |
| Pre-drilled hole | Ø12.4 mm |
The M12x1.75 V-Coil thread repair insert is a resilient coil made of Helicoil-type stainless steel wire. Installed in a hole tapped with a thread repair tap, it restores a fully functional M12 thread for a standard bolt. This solution does not require a larger bolt or replacement of the entire part. The 3xD version, 36 mm high, is used with soft materials and bolts tightened to higher torques. Dimensions are specified by DIN 8140, form A, which is the free-running version.
M12 thread repair step by step – from the hole to the completed joint
Four installation steps in the V-Coil system
Thread repair process M12 × 1.75
1Prepare the hole
diameter: Ø12.4 mm
2Tap the thread
tool: V-Coil 4H
3Screw in the insert
length: 3×D
✓Restore the joint
thread: M12 × 1.75
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 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 M12 tap cannot prepare the insert hole
A pitch of 1.75 mm means a wire thickness of approx. 1.14 mm (the 0.65 × P rule).
The installation thread for the insert is therefore approx. 14.28 mm in diameter — approx. 2.3 mm larger than the nominal 12 mm of an M12 thread.
It can only be prepared with a tap M12 4H V-Coil after drilling Ø12.4 mm; after repair, the screw engages a standard thread M12 × 1.75.
M12 thread repair in steel, stainless steel, cast iron and aluminum
When to choose the 3xD version
The insert restores threads in steel, stainless steel, cast iron, and aluminum, as well as magnesium and plastics. Length selection depends on the parent material and bolt property class. The 3xD version is suitable for soft materials and bolts of property class 8.8 and higher, where a larger load-bearing area is important. A shorter insert is selected for shallow holes in steel and cast iron. A longer one is used where the material is soft and the bolt is tightened to a high torque. In practice, M12 is used in machine mountings and steel structures, among other applications. The hard wire thread distributes the load evenly, and the first thread carries 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.
M12 3×D insert compatibility – required V-Coil system tools
Check before purchasing
✓Nominal thread: M12 with a pitch of 1.75 mm.
✓Tap: special M12 4H V-Coil thread repair tap.
✓Tap drill hole: Ø12.4 mm drill bit.
▲Depth: space for an insert 36 mm high and proper seating.
▲
Application limitations
The thread for the insert must be cut with an M12 4H V-Coil STI tap — a nominal M12 thread is too small for the insert to anchor in it. The free-running version does not prevent the bolt from loosening: threadlocker or a screw-locking insert helps under vibration.
A correctly installed M12 3xD V-Coil thread repair insert transfers loads so that the bolt shank fails before the thread in the material. Plan the hole depth: the insert occupies 36 mm, or three thread diameters (3 × 12 mm). In series production, the same insert serves as preventive reinforcement.
Frequently asked questions
The length is determined by the parent material and bolt property class: the weaker the material and the stronger the bolt, the longer the insert. For steel, cast iron, and shallow holes, 1.5xD is sufficient; 2xD is standard for aluminum, while soft materials and bolts of property class 8.8+ require 2.5-3xD. The insert shown is the version 3xD (36 mm).
The top coil 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 before the bolt is installed.
Yes, because insert dimensions are specified by DIN 8140 and additionally by ASME B18.29.1. This makes products from Helicoil, V-Coil, Recoil, and BaerCoil interchangeable. Matching size, pitch, and length are what matter.
Yes, the same inserts are installed at the factory to reinforce threads in cast iron and aluminum. The thread gains the hardness of wire with a minimum tensile strength of 1400 MPa and an even load distribution. This also increases the fatigue life of the joint.
Product accessories
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.