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P-series clutch (up to 1994)

Introduction

The original clutch on the Vespa P-series scooters was either a 6- or a 7-spring clutch. The 7-spring clutch was used earlier with the Rally models which required a more robust clutch owing to the greater engine power of these models. The 7-spring clutch was also found on the P200. The 6-spring clutch was found on many earlier large-frame Vespas.

P series Clutch 7-spring.jpg

The image above is of a 6-spring clutch.

The design of the clutch, whether 6-spring or 7-spring, is the same apart from the differing number of springs. It consists of three cork "friction" plates and two steel "plain" plates which are laid in the clutch basket in alternating fashion (cork, steel, cork, steel, cork). When the clutch is engaged the springs apply pressure to all the plates, sandwiching them together and causing the clutch to rotate. When the clutch is disengaged, the steel plates are free to move independently of the cork plates. Whenever the engine is running the clutch is bathed in gear oil – hence the description of the clutch as a "wet clutch".

The springs are located in the basket in removable and replaceable steel cups (Part 9 in the diagram above) and the plates are held inside the basket by means of a large circlip (Part 1).

The clutch is located on the crankshaft by means of a woodruff key and it is secured to the crankshaft itself by means of a special castellated nut (for the removal of which a special tool is required). The torque wrench setting for this nut is 28.93 - 32.55 lbf ft.

castellated clutch nut.jpg

The castellated nut used to secure the clutch to the crankshaft.

clutch nut tool.jpg

The special tool used to remove the clutch nut from most Vespa clutches up to 1994

Aftermarket, Modern Versions of this Clutch

On the market today, performance versions of these clutches are manufactured by various engineering firms. 8-spring versions of the clutch are also to be found. Stronger springs, CNC-milled baskets, and clutch plates made from high-tech materials such as carbon compounds, are features of these clutches.

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Paul McIntosh,
Mar 25, 2015, 1:40 AM
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Paul McIntosh,
Mar 25, 2015, 1:40 AM
ą
Paul McIntosh,
Mar 25, 2015, 1:40 AM
ą
Paul McIntosh,
Mar 25, 2015, 1:40 AM
ą
Paul McIntosh,
Mar 25, 2015, 1:40 AM
ą
Paul McIntosh,
Mar 25, 2015, 1:40 AM
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