XRAY - Model racing cars

If I put a shim between the wheel and the hexagon in the fron and the rear... the car is wider both in the front and in the rear.
What effects can cause this?

The difference by making the car wider using offset rather than using different shims on the suspension mounts for the arms is that the shock positions and upper link lengths remain the same, but lateral grip is increased, without the slower response of a longer link or more outward mounted shocks on the arms.

As you add offset shims you will have increased lateral grip on that end of the car.