Hi Alice,
Yes, the 2 driving wheels is not the best configuration ! I used this solution to my first CK but I had a lot of trouble when cornering....
At first, I simply deleted a key on a wheel
This simple solution gave me a good result, the steering was nice but less symmetrical
With two-wheel drive turns are difficult but the behavior is neutral, with a single drive wheel, turns are nice but the car becomes less neutral
Moreover, in turns "against" the free wheel there is more motor, hence my idea of isque "limited slip"
Be careful, this disc is not nylon but polyacetal or PEHD 500
I tighten the ring until I can not turn the wheel by hand
Thus, the wheel is still a little drive and a little braked and the car found a little neutrality, this concept is not "miraculous" but it works better than a wheel too free which gives asymmetrical effects in control....
I hope my Googlish is understandable enough to explain my idea ....
Fabrice