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Gear Cog 51 teeth, 3rd gear,
DRT "4-gear PK" for Vespa
50 S 3°/Special V5B3T 3°/V5B4T
2°/SR (D)/100 2°/125 PV 2°
Ø 104,5 mm, h 10 mm, mid
section: 4,2mm, "short 3rd
DRT stands for the Denis Racing Team and is a guarantee for race proven gear box components, based on experiences collected in Rally Sport. The racers and mechanics on the Italian sprinting scene swear by the DRT products and these high end gearbox parts are also included in the racing scooters of the SIP-STOFFI racing team.
Well coordinated gear ratios helps your motor deliver its power more smoothly and constantly and can be decisive over a win or loss in a racing situation. It is almost an art, to be able to set your gearing up to remain within the power-band every time you change up to another gear. If you have ever been happily accelerating behind a truck on the motorway just to lose all of your power while attempting to overtake due to the extra wind resistance will appreciate the use of the shorter fourth gear cog.
The gear cogs are made of a tougher grade of steel and then hardened. This makes them especially suited to the more hard working environment of a performance orientated motor and also noticeably more durable. The cog teeth are straight cut, CNC machined and have had metal removed to lower the overall weight.
Helpful hint: If your motor has enough power to give you the impression you could still change up a gear while travelling at top speed, than you could probably do with a taller 4th gear. If the gap between 3rd and 4th gears seems a little too wide, than a shorter top gear will probably help.
Conclusion: These DRT gear cogs are essential for all serious racers and sprinters. Rally going scooterists have also learnt the benefits of top quality adjustable gear box ratios.
SIP-TIP: If you want to raise the ratio of your gear box start with the primary drive gears. Never forget to order a new gear selector cruciform (at best the DRT item) and fresh gear box oil. Last but not least the SIP gear box shaft assembly spacers help you find the ideal output shaft assembly end float for safe and enduring use of your motor.
Depending on your motor type there are the following gear cogs available:
DRT 'PK 4-gears'
Suitable for : VESPA 50 S 3°/Special V5B3T 3°/V5B4T 2°/SR (D)/100 2°/125 PV 2°/ET3 2°/PK50/S/SS/XL/2/FL/PK80-125 S/PK125/ETS/N//XL/XL2.
The 'PK 4-gears' is the most commonly used type of gearbox set up in performance orientated small frame motors. All four-geared small frame models produced since around 1976 are factory equipped with this gearbox type.
The 'ROVIGO' tall 1st gear is renowned for its excellent acceleration qualities, ideal in both sprint and circuit racing, due to its cog ratio being very close to that of the 2nd gear so minimizing the gap between them. The extra tall 1st gear in combination with an even taller 2nd also ensure an ideal gearbox set-up for sprint and circuit racing.
The short 2nd and 3rd gears are excellent especially when used in combination with the DRT input shaft assemblies. (The third gear cog with 51 cog teeth does not work in combination with the DRT SINCRO Replica or Sincro input shafts). If you want to use the third gear with 51 cog teeth the OE PIAGGIO input shaft will have to be used.
The RSP 3rd gear cog with 49 teeth is delivered with a specially modified gear selector spider produced by DRT. This package stands out with its extremely low production tolerances and was designed specifically for high end motors with a cubic capacity of over 140cc and a power output of between 30 and 40 PS. It is ideal in combination with either the OE PIAGGIO input shaft or the high end DRT items coupled with a shorter 3rd gear on the output shaft.
It can be difficult to bridge the gap in ratios between 3rd and 4th gears. In case travelling two-up (with luggage), going up a mountain pass or even overtaking on the motorway is becoming increasingly frustrating, DRT have-in combination with their very own input shaft assemblies- the answer. If the width of your power band does not allow you to bridge the gap between 3rd and 4th gears, then you can consider the use of a shorter 4th gear or the recently produced new input shaft assembly, developed to address this very problem, produced by DRT. The PARMA shortened 4th gear cog can be used in combination with a DRT input shaft assembly. The use of this high end item also enables even finer gearbox ratio tuning possibilities than can be achieved with the OE PIAGGIO items.
OEM Numbers (for the purpose of comparison)
ICs 3^z51 163/A F1 (DRT)
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