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Input Shaft Assembly 21-18-14-10 teeth DRT "short 4th gear" for Vespa 50 S 2°/Special V5B3-4T/SR/SS/90 R/SS/100 2°/125/PV/ET3/PK50-125/S/XL/XL2
Part no.: 40442400
Including VAT Free shipping
324g / Piece
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Product image for 'Input Shaft Assembly 21-18-14-10 teeth DRT "short 4th gear"Title' Images may differ from the original
Product image for 'Input Shaft Assembly 21-18-14-10 teeth DRT "short 4th gear"Title' Images may differ from the original
Product image for 'Input Shaft Assembly 21-18-14-10 teeth DRT "short 4th gear"Title'
Product image for 'Input Shaft Assembly 21-18-14-10 teeth DRT "short 4th gear"Title'

Input Shaft Assembly 21-18-14-10 teeth DRT "short 4th gear"

for Vespa 50 S 2°/​Special V5B3-4T/​SR/​SS/​90 R/​SS/​100 2°/​125/​PV/​ET3/​PK50-125/​S/​XL/​XL2

  • with M11 nut
  • for 4th gear, 46 teeth
5 ratings
Including VAT Free shipping
324g / Piece

Product description

Clean gear changes while you are accelerating can be decisive over defeat or victory. It is almost an art to be able to setup your gear ratios ideally to match the area of your rev range where maximum power is available (the power band). The VESPA gear box components have seen a lot of experimentation and development in recent years. DRT are at the forefront of this research and have suitable gear box parts available to suit most possible motor setups.

The problem of a clean gear change between 3rd and 4th gears, especially with performance enhanced motors, is shared between both the large and small frame VESPA motors. DRT offers new gear ratio setups with their range of input shaft assemblies. Maximum engine revolutions in 4th gear with a 150 kg load over a longer distance or race use of the 4th gear, everything is possible.


DRT input shaft assemblies are made of a tougher than standard grade of steel and then hardened through tempering. They are therefore extremely durable and so offer an ideal extension to the vast range of existing gear box components available. The gear ratios are much easier to adjust to the particular motor characteristics required. Most of the input shaft assemblies are equipped with a fine M11 grade thread and the nut to fit is also included.


Conclusion: These DRT input shaft assemblies 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. The input shaft upgrade is first, followed by the adjustment of the individual gear cogs on the output shaft. 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.


You can choose from the following DRT input shaft assemblies:

An input shaft assembly with a shorter 4th gear ratio: Shorter 4th gear without output shaft assembly cog replacement, also available for the APE three wheelers. A simple and effective introduction to the world of input shaft assembly tuning.

The DRT input shaft assembly including gear cogs with 21, 18, 14 and 10 teeth respectively enables a shorter 4th gear cog with 46 teeth and is most effective in small frame motors with between 15 and 20 PS. This conversion kit is most popular in combination with POLINI 130cc cylindered tuning projects.

Conclusion: An input shaft assembly with a shorter 4th gear ratio. A simple and effective first step into the world of gear box ratio tuning.

OEM numbers (for comparisons): ClusterI Scp z21.162/4^RAVVICINATA (2.19) - 18663 (DRT)

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Product name In stock, product no. Price
Input Shaft Assembly 21-18-14-10 teeth 4-speed/PK DRT "short 4th gear"
Part no.: 4043185F
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Merkzettel 22.12.2020 rollerbutze December 22, 2020 32 View notepad
Grubsi m1l ChristophK January 15, 2021 19 View notepad

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File name File type Description File size
Technik_Getriebe Technik Getriebe 8,54 MB Download
Getriebe Techtipp Getriebe Smallframe 6,12 MB Download
Nebenwelle DRT DRT Nebenwelle Smallframe 0,02 MB Download
Techtip gearbox smallframe Technik Getriebe Smallframe EN 2,75 MB Download
COBRA primary drive COBRA Primary drive 0,48 MB Download
Getriebevorschläge mit Primär Cobra Getriebevorschläge mit Primär Cobra 3,73 MB Download
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