Reverse Engineering


I am working currently on an optimized drive kit. The basic idea is to go for a direct drive based on my experience that I am running always in the 3rd gear. As on of first action I contacted a specialized company to scan an existing gear-box-housing (company name:

The first scan created raw data in the are of 260 MByte (*.stl-file) with an accuracy of 0.02mm. The data was then reworked into a parametric model with a reasonable size of 4 MByte (*.stp-file). Such a small file can easily be handled in every CAD tool.

Why a direct drive?

There are different reasons:

  • There is no need for changing gears since an electric motor provides the max. torque from zero speed. Hence the gear changing mechanism and its pinions can be removed.
  • A direct drive (only differential) has less parts. Less parts means less noise, less weight, nearly no backlash and higher efficiency.
  • My current drive needs an oil pump to supply the input pinion with gear oil. Without the input pinion I can get rid of the oil pump.

The next steps will be to start defining the different parts to fix the electric motor on top of the gear-box and to couple it with the main axle driving the differential.
I will keep you posted about the upcoming design steps.
Cheer Erich


  1. That looks nice Erich!! It will be really interesting to fix a direct drive and that way get not to use oil.
    How is it going?

    • Hi Jon,
      Was quite busy recently with another upgrade I do on the battery side – that’s why there was “radio silence” regarding the direct drive project in the last weeks. Keep you posted soon.
      Cheer Erich

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