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- Vespa Classic
- Half-moon wedge set -FABBRI RACING hardened- Vespa Smallframe V50, PV, ET3, PK - suitable for pole wheel, primary, clutch
Hardened parallel key set from FABBRI R ACING for Vespa Smallframe - suitable for pole wheel, primary and clutch.
The FABBRI RACING crescent key set is a hardened key set for Vespa Smallframe engines. It is used on the corresponding grooves of the crankshaft and auxiliary shaft and replaces the often very soft standard half-moons or feather keys. The hardened design reduces crushing or deformation of the parallel key during installation and ensures clear positioning of the pole wheel, primary and clutch on the respective shaft.
The key or crescent key is primarily used for positioning. It determines the position in which the pole wheel, clutch or primary sit on the shaft. This is particularly important for components with a fixed reference position, such as the pole wheel in conjunction with the ignition. However, the actual power transmission does not take place via the parallel key, but via the frictional connection of the conical or flat contact surfaces.
Standard parallel keys are often very soft. They can be crushed or deformed by repeated assembly, slightly damaged grooves or components that do not fit properly. The hardened FABBRI RACING version is the more robust solution here, provided the contact surfaces of the shaft and component bear correctly.
This set is not a remedy if keys on the pole wheel, clutch or primary regularly shear off. A feather key must not transmit torque. If it shears off, this is almost always an indication that the frictional connection between shaft and component is insufficient.
If a parallel key keeps shearing off, the problem is usually not with the parallel key itself. Often the pole wheel, coupling or primary are not bearing sufficiently on the shaft. As a result, the component works minimally on the shaft until the key, as the weakest part, is sheared off. The solution is therefore to improve the accuracy of fit between the surfaces.
A simple aid for checking and improving the load-bearing surface is valve grinding paste from four-stroke engine construction. This is a paste-like grinding paste based on corundum, which can be used to carefully grind two conical surfaces together.
Sanding paste must be completely removed after sanding. Residues can act as an abrasive in the motor environment or make subsequent disassembly of the pole wheel, clutch or primary extremely difficult. After grinding, carefully clean and degrease all contact surfaces, grooves and threaded areas.
| Vespa 50 / N / L / R / S | V5A1T / V5SA1T, 2T AC |
|---|---|
| Vespa 50 Special / Elestart | V5A2T / V5B1T / V5B3T and Elestart versions |
| Vespa 50 SS / Super Sprint | V5SS1T |
| Vespa 90 / 90 Racer / 90 SS | V9A1T / V9SS2T / V9SS1T |
| Vespa 125 Primavera | VMA2T |
| Vespa 125 Primavera ET3 | VMB1T |
| Vespa PK50 / PK50 S | V5X1T / V5X2T |
|---|---|
| Vespa PK50 XL / XL2 / HP | V5X3T / V5N2T and other PK50 models |
| Vespa PK50 SS | V5S1T |
| Vespa PK80 / PK80 S | V8X5T |
| Vespa PK125 S / XL | VMX5T / VMX6T |
| Vespa PK125 ETS | VMS1T |
| manufacturer | FABBRI RACING |
|---|---|
| type | Half moon wedge / parallel key set |
| Version | hardened |
| Suitable for | Vespa Smallframe V50, PV, ET3, PK |
| Positions | Pole wheel, primary, clutch |
| Shafts | Crankshaft and auxiliary shaft |
| Function | Positioning of the components in the groove |
| Power transmission | via the cone or contact surface, not via the parallel key |
The FABBRI RACING half-moon key set is a useful hardened replacement and revision part for Vespa smallframe engines. It replaces soft or crushed standard keys and ensures clean positioning of the pole wheel, primary and clutch. However, if feather keys regularly shear off, the frictional connection via the cone and contact surfaces must always be checked and improved.
