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.