Torque springs are important for the transmission set-up. The spring transfers pressure onto the torque driver and so strongly influences the vario's 'shifting' characteristics. You'll know that it's necessary to go for a stronger spring when the drive belt keeps slipping, the vario doesn't shift smoothly within the ideal rpm range or the engine keeps running below the ideal rpm range despite using lighter rollers. After replacing the torque spring, the vario will have to be readjusted. Polini's Evo Slider plastic spring plate gets rid of the problem caused by twisted springs, which have negative consequences for the transmission's shifting characteristics. The torque spring sits no longer directly on the clutch, so that the twisting can be minimised. Furthermore, transmission vibrations at high revs are reduced. The results are better shifting characteristics coupled with smoother engine running. The larger the diameter, the stronger the torque spring.