Rebuild your vintage Vespa clutch

Modified: 2009/06/29 15:53 by admin - Categorized as: Tech Tips - Articles
Note: One of the most common repairs that can be done by the home mechanic is the Clutch Rebuild.

1: Remove the clutch cover

2: Stuff an old rag in between the bottom of the clutch and case. You don’t want anything falling into the case.

3: Remove the clutch by undoing the center nut behind the pressure plate. First you have to bend the tab up securing the clutch nut in place. Then loosen the nut by turning counterclockwise. On most models this requires a special tool. This tool is available from any Vespa shop. You will have to keep the clutch from turning. This can most easily be done by replacing one of the clutch cover bolts, inserting a screw driver in the side of the clutch and rotating the clutch counter clockwise until the screw driver hits the bolt. There is also a very handy tool for this called a clutch holder tool.

4: Pull the clutch off. It will probably be stiff but it will come off. If it doesn't want to slide off easily, put screwdrivers behind it 180 degrees from each other and "walk" it off.

5: Compress the clutch and remove the retaining clip. To compress the clutch you can get a clutch compressor or use a large bolt, 2 large washers, and nut. With the clutch compressed you can easily undo the clip and remove the plates.

6: Inspect and/or replace all of the items below. If something looks warn then replace it. It doesn’t pay to skimp. It just means you will have to do this all over again in a very short while.

7: Oil everything liberally and reassemble. Make sure you have the woodruff key fully seated when putting the clutch back on.

When rebuilding a clutch, these are the components that should be thoroughly inspected and replaced if needed:

The Bushings:
Most Vespa clutches have 2 brass bushings in them. These 2 bushings wear out and cause the clutch to grab unevenly (clutch lurch). This problem mimics "popping" the clutch to do a wheelie. This condition not only damages the clutch assembly, it also stresses the spring gear assembly.

The Basket (aka Bell Housing):
Another item in the clutch that tends to get over looked is the basket. This is the part that the clutch plates slide into. This unit tends to flare open under heavy use and causes the clutch plates to bind. To check and see if the clutch bell is damaged all you need to do is try to fit the outer clutch plate (plate with cork only on one side) into the bell. If the plate drops in easy then the bell is OK. Another thing to look for in the clutch bell is any divots in the edges where the clutch plates engage the bell. If there are any divots in these surfaces the clutch plates will "hang up" and not release properly.

Clutch Plates:
These are what make the clutch work. Both the cork plates and the steel plates should be replaced when you overhaul your clutch. Soak the cork plates in oil overnight if you have the time or at least for a couple of hours. This helps ensure your clutch won’t stick together after you finish the rebuild. Give the metal plates a mild sanding with some 400-grit paper to prepare the surface.

Clutch Springs:
The springs tend to lose their stiffness over time so you should replace them. Plus they are so cheap it doesn’t pay not to replace them now.

Clutch Nut and Tab Washer:
The clutch nut can get really torn up when you are trying to get it out so you may want to have one on hand if you need to replace it. The tab washer is vital in making sure the clutch nut does not come undone. Replace the tab washer in any event.

Woodruff Key:
The clutch woodruff key must be in perfect shape. It keeps the clutch from spinning on the end of the crankshaft. Replace it if looks even the remote bit suspect.

Pressure Plate and Push-out Bearing:
The pressure plate and push-out bearing are the pieces that make the clutch engage and disengage. The pressure plate should have a nice smooth surface and the push-out bearing should still have the groove across the face visible. If either part looks wprn replace it.

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