Simple Torque Convertor

This is a prototype of a simple Torque Convertor for a toy racer or other small mechanical device that would profit from a smooth take-off.
The thing must be filled with oil in order to function and it needs to be glued so the oil remains inside.
It works well at anything between 200rpm to 1500 rpm. It's output is about 7:1. It is off course quite energy-inefficient, but you probably figured that out already. :)
Any input to improve the design is welcome !