Vespa Small Frame Engine Work

Gearbox Disassembly

Once the cases are split you will have access to all the bearings and gearbox components to check and replace as necessary. This section will show how to remove the transmission from the cases.

The Vespa Primavera engine in the shots below may be slightly different than your engine but most pictures will give you enough of an idea how to proceed.

First we'll remove the kickstart from the casings. This will allow you to replace the kickstart O-ring which is a common place for oil leaks. It also will give better access to remove the primary drive gear. The free gears have already been removed in the images. Move the kickstart with your fingers until the small kickstart gear can be removed.


Once the kickstart gear is removed you will see a spring which can also be removed. The kickstart spring was previously removed so it is not shown in this picture.


The kickstart can then be pushed through the casing and placed aside for the rebuild.


With the kickstart out of the way you will see a small dished washer around the exit of the primary gear shaft as well as a small circlip.


Remove the dished washer and note that the dished part faces up and towards the flywheel side of the casings.


Using circlip pliers, remove the single circlip that holds the primary gear shaft in the bearing.


Flip the casings over and carefully tap out the main axle using a rubber faced mallet. If you don't have one, you can just thread the axle nut on the axle so that it is flush with the end and the treads are protected and use a normal finish hammer.


Carefully bang the axle out of the bearing always watching the shift cross location. When the shift cross is all the way down on the circlip you'll be able to disengage it from the small selector "ears" of the selector assembly.


Then carefully bang the clutch basket out from the central bearing.


It is a tight fit but it will come out of the bearing and out the clutch side casing opening.


Above is a shot of the clutch basket just clearing the bearing from the clutch side of the motor casing.


To remove the clutch bearing, use circpli pliers to remove the single retaining clip. The bearing can now be removed by banging it out from the other side. Use a large socket as a block so that the rim of the socket is resting on the outer rim of the bearing. Tha main crank bearing can also be removed in a similar manner.


The gear cluster on the flywheel side of the casing may be stuck in the bearing. Sometimes the bearing is tight to the casing but sometimes they come out together. If this is the case you can use a bearing splitter to force it off the shaft.


The bearing can now be cleaned and reused if it feels good, or replaced.


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