Previously released for the RX8, Xray have now released these conical clutch washer springs for the NT1 clutch. These spring washers offer more consistent clutch operation for maximum punch. When using the standard spring, after the clutch is set for the first time the spring becomes deformed over time and needs retightening. This new conical clutch washer spring set allows the clutch to retain its setting for a very long time without needing readjustment.
Source: Xray [teamxray.com]
