4th gear cog -DRT- Vespa P-range (-1984), PX EFL, T5 125cc, Cosa, Rally - 125-150-180-200cc - (short -1) - 36 teeth

The abbreviation DRT stands for Denis Racing Team. Denis Innocente found his way into scooter parts production via the acceleration racing scene in Italy. With more than twenty years of background in motorsport, he now mainly produces gearbox and clutch parts for the Vespa. The Italian scene swears by the DRT parts. Thanks to the different primary and gear wheels, you now have unprecedented freedom in the gradation of your gearbox. So you can build a gearbox with your desired gradations. From a close-ratio racing gearbox to a touring gearbox for the gear-shifting slacker. For lower mass acceleration, the DRT gears are lighter in weight.

NOTE

: The 36 tooth fourth gear was developed by Piaggio for the 125cc models. It was constructed by a so-called tooth flank shift from the 4-speed of the 150/180/200cc models with 35 teeth. By this technique the gearing of the auxiliary shaft could be kept identical for all models. A disadvantage of the 36 tooth gear is however the narrower tooth base. This results when more teeth have to be accommodated on a given diameter. The narrower tooth base is of course not as stable as the 35 tooth gear, which is why Piaggio only used it in the 125cc models.

The short 36 tooth gear is however very popular with performance increased 200cc engines. With very sporty engine designs, the jump from gear 3 to gear 4 is too big and the engine no longer gets into its power band. With today's very high-torque concepts (like Malossi Sport/MHR or Quattrini M244) this tuning trick from the 1990's is still often used.

We strongly recommend to use a 4 speed with 35 teeth. The high engine torque together with a load peak (gear jumping, shifted etc.) can otherwise damage a 36 tooth gear. If you still need a shorter gear jump, you should realize this with another auxiliary shaft with less teeth (e.g. BGM6505 or BGM6506)

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