Polini springs that increase pressure by 30% and is therefore ideal for tuned engines. The springs press the gear on the rear converter onto the belt. It also creates pressure to shift the variator. A lighter pressure is required once a motor has been tuned to prevent the engine from moving into a dangerously high rev range. The pressure of the springs is closely tied to the variator. If a spring is fitted, it must be matched to the variator. Original spring weight: 50/20mm/kg. Polini spring weight: 50/26mm/kg. Spring thickness: 4.2mm. Total length: 90mm. Internal diameter: 50mm. Number of coils: 5.