Drive Unit Assembly

Drive unit: Motor combined with old gearbox

Bommy (see comments) asked my to explain how I did the coupling of the old gear box with the electric motor. I added some further pictures under the tap “drive train”, which show how it was done

Basic Idea

The basic idea was to insert a new shaft in place of the old crank shaft which supports and holds the old input pinion exactly at the same position as it was before. The input pinion was then coupled with a tooth belt pulley so that the electric motor can drive the gear. Sound as it was a piece of cake – but it wasn’t!

A Challenge – hot Bearings and Input Pinion

There were several small challenges. E.g. I tried to run in a first approach the new shaft and its greased bearings and the old input pinion without active oiling. But during first runs the outcome was that the pinion and  shaft bearings got too hot due to the friction (input to 2nd pinion) and fast turning of the shaft (grease). Luckily a colleague of mine – crazy chap who restores in his spare time old Range Rovers – helped me to add an oiling system. We placed an additional oil pump which provides the bearings and the input pinion with oil. Now the drive unit runs soothly and very efficient.


I’ve seen other solutions how to couple motor and gearbox of the Mini. For instance a solution where the electric motor was directly coupled with main axle of the gear box. This is a very smart and compact design with less turning parts. It needs no additional shaft, input and 2nd pinion nor oiling system. However I do not know how the sealing of the axle was done so that no oil leaks out of the gear box. If there is someone out there, who knows how to do it, then please let me know …. ;-).

Happy New Year  …  Erich Butler

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