Standardl 29 mm? 18 mmstiffness: 5,3 N/mmstandardProduct descriptionSometimes in the hectic of a complete motor overhaul the smaller parts such as the clutch springs are overlooked when it comes to renewing. To create friction in the clutch the springs included in the assembly press the surface frictional area of the friction plates onto the plain separator plates. These in turn are exposed to high mechanical energy. When the friction between the respective clutch plates adds up to more than the torque coming from the crankshaft, the power can be transferred further to the gearbox. Over time the clutch springs become weaker or can even break. For these reasons, and more, they should be regularly replaced. We also recommend stronger grade springs to be used (available in varying grades) even for the more milder road tuning-projects to enable all of the extra power created to reach the rear wheel. Conclusion: If you are upgrading or even only servicing your scooters motor, do not forge