Gearboxes & ratios
for Vespa 50-125/PV/ET3/PK/XL by SIP Scootershop
Here you can find the gearboxes & ratios for Smallframe Vespas Vespa 50-125/PV/ET3/PK/XL.
Differentiation 4-speed gearshift clutches Vespa Smallframe models
For the 4-speed engines of the Vespa Smallframe models, there are two different gearshift clutches which fit different gearboxes or their gearwheels. It is important that each gearbox is always mounted with the corresponding claw. The small shift arms that engage the gear wheels are at different distances from the recesses that lock the gear. If a gearbox is fitted with the wrong shift dog, this will result in gear jumping.
There are two characteristics that can be used to distinguish between the two types of shift dog:
1. the shape of the transition of the 4 small wedges that engage the gear wheels to the upper end of the claw. The later "PK type" has a radius there, so it is round. The earlier "V50/PV type" is angular at this point.
The second feature is the height of the shifting claw. The "PK type" is 50.2 mm high, the "V50/PV type" is 51 mm high.
Today, there is a whole range of manufacturers who produce gearshift claws for tuning and racing purposes. Unfortunately, some suppliers no longer adhere to the classic distinguishing features. DRT, for example, no longer makes the round gearshift dog round and CRIMAZ, for example, makes the 50.2 mm gearshift dog in 48.8 mm. This does not change the function and purpose. But it makes the distinction and the clarity in our shop a bit more complicated.
Therefore, we have decided to indicate either "type round/50.2 mm" or "type square/51mm" for each 4-speed smallframe gearshift claw. This way, all gearshift claws can easily be assigned to the correct gearbox, even if the actual design differs.
By the way: The two gearbox types can of course be assigned to models and chassis numbers. The problem is that the PK version was built into some predecessor models earlier. In addition, many old models have been fitted with other engines over the years, or the engines have been fitted with other gearboxes. It is therefore always advisable to check which gearshift detent is installed and whether it actually engages correctly with the existing gears.