You set the tweak on the car when you build it by placing the components on the car so it is equally weighted from left to right. Then every time you go on the track, you make sure that the left and right front tires are of equal diameter and the left and right rear tires are of equal diameter. As long as you don't bend something, the tweak should not be too far off. It is a challenge to get the components on the car and keep the car balanced.