The primary gear cog, combined with the clutch drive cog, completes the primary drive function in the gearbox of every geared Vespa model. It is solidly riveted to the output shaft and also directly linked to the input shaft. The higher the power output of the motor, the taller the gearing should be. This allows the extra power to be transformed into higher maximum road speeds.
This primary drive gear cog can also be combined with all Vespa PX models clutches. The original clutch can no longer be used. To make the PX clutch align correctly a CNC machined spacer washer (#17650000) will also be required. This primary drive cog is available with either 65 or 67 cog teeth.
SIP-TIP : Do not forget to order a suitable DRT primary drive repair kit (#16020770).