Most of the front wheel steering assembly had to be replaced by new 3D-printed parts. The same is true for the rear wheel base as it was replaced with an aluminum mounting plate.
The controllers was flashed to a new alternative firmware developed by Larsmm, which is a fork of the original work by NiklasFauth, rene-dev, and crinq. This firmware provides four driving modes with different speed, acceleration, turbo activation, and smooth acceleration and breaking ramps!
A complete build with all the steps and detailed photos is available on the project wiki page.
thats cool! I thought of the same for a Kettcar. By the way i wrote a how to to program STM32F103 via MBED Online compiler https://hackaday.io/project/168990-nucleo-swd-mbed-to-reprogram-storm32-controller