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Description
FINISHED THREADM7 × 1
TOLERANCE4H
PRE-DRILLED HOLEØ7.2 mm
LENGTH L172 mm
M7 thread repair tap – STI tap for V-Coil M7x1 inserts
Tool dimension table and technical data
| V-COIL M7 THREAD REPAIR TAP | |
|---|---|
| Thread to be repaired | M7 × 1 |
| Tolerance class | 4H |
| Tap diameter B | 8.3 mm |
| Overall length L1 | 72 mm |
| Flute length L2 | 22 mm |
| Shank diameter D2 | 9 mm |
| Square drive a | 7.1 mm |
| Pre-drilled hole | Ø7.2 mm |
The V-Coil M7 thread repair tap cuts an STI (Screw Thread Insert) thread for a Helicoil-type insert. The tool restores a load-bearing thread in a damaged hole without increasing the screw size. Once the insert is screwed in, the hole again accepts a standard M7 screw, without moving to a larger size. The 9 mm shank with a 7.1 mm square drive fits typical hand tap wrenches, making workshop use easier.
Repairing a stripped M7 thread in steel, stainless steel, cast iron, and aluminum
Materials, tips, and limitations
The tool works in steel, stainless steel, cast iron, and aluminum, covering the full range of structural materials. Threads strip most often in soft metals, while in steel the insert improves the fatigue life of the joint. A typical example is repairing a brake caliper bleeder screw thread, including in an aluminum body, where the insert restores the thread without replacing the entire caliper. Drill the pilot hole with a drill bit Ø7.2 mm for the STI tap. Drill at the upper tolerance limit and tap with coolant.
The cut STI thread has dimensions conforming to DIN 8140-2, so the M7 thread repair tap prepares a hole for any insert conforming to this standard — lengths of 3xD are available in the store. The tool measures 72 mm (L1) with a flute length of 22 mm (L2), and the repaired thread carries loads comparable to or greater than those of the original.
M7 thread repair step by step
From drilling to the nominal thread
Repairing with an insert is faster and less expensive than replacing an entire brake caliper with a stripped M7 bleeder screw thread.
Thread repair M7 with a wire insert
1Drilling
Hole: Ø7.2 mm
2Chamfering the hole entrance
Angle: 90–120°
3STI tapping
With coolant, 4H
4Insert installation
Tang: break off
✓Nominal thread
Screw: M7 × 1
In a blind hole, remove the broken-off tang before installing the screw
Helicoil M7 tap (STI) – why it is larger than a standard tap
Compensating for the wire thickness of the thread insert
The STI tool differs from a standard M7 tap only in profile size — the 60° angle and 1 mm pitch remain metric. The insert wire occupies space on both sides of the profile, so the diameter is D STI = 7 + 1.3 × 1 = 8.3 mm; hence the nonstandard 8.3 mm cutting section, which neither an M8 nor an M9 tap can provide. Tolerance class 4H (equivalent to inch class 3B) is also used for screw-locking inserts, while the finished thread after insert installation is class 6H.
Tap compatibility with the V-Coil insert
What must match before starting the repair
✓Matching size: V-Coil M7 insert with a 1 mm pitch.
✓Matching hole: prepare a Ø7.2 mm diameter before tapping.
✓Matching version: available M7 insert lengths: 3xD.
▲Required inspection: depth and wall thickness of the component being repaired.
This is not a substitute for an M7 tap
The tool cuts only an oversized thread for an insert. A standard M7 bolt will not engage in a hole tapped this way without an insert, and a standard tap will not prepare the hole for an insert.
Frequently asked questions
For the STI insert, use a drill bit Ø7.2 mm, rather than 6 mm as for a standard M7 thread. Drill at the upper tolerance limit so the insert seats properly. Chamfer the hole entrance at an angle of 90 to 120°.
No, because the STI thread has a nonstandard cutting diameter 8.3 mm. Neither M8 nor M9 can reproduce this profile. With an incorrect thread, the insert will not lock properly in the hole.
Yes, the inner edge of the wire recreates the nominal thread M7 × 1. The minor diameter after installation is approximately 5.92 mm and conforms to ISO 724. The screw can be installed without any modifications.
The insert restores only the mechanical thread of the M7 hole. Banjo connections and bleeder screws are sealed by the seating surface or washer, not by the thread itself. After the repair, check the condition of the seating surfaces and install new washers.
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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 |
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