Roll center debate

[Tony Arnold]

That was a really good explanation on where RC is located. But there are also some areas you also need to consider that will play a roll with RC. One is the location of each instant center which is the point at which the upper control arm angle and lower control arm angle intersect. In todays Stock car or even road racing front end geometry the instant centers are in the center of the tire patches and as low as you can get them. Another thing to look at is not where the RC is staticly, but where it goes under dive and roll. You may have it in the are you want it but going thru a corner it maye move left, right, up or down. The rear RC being located low with high sprig rates does a couple things. It will allow the rear of the car to roll more which transfers more weight to the LF or RF depending on the way your turning. This makes the car tight or push. The way that is corrected is big rear springs. The springs will help the car rotate thru the turn will freeing the car up. The low trackbar will also make ALOT of forward bite. The big Front sway bars do the same thing. They control roll and transfer weight very fast which make forward bite. There are a few things you can do with the front geometry to allow you to run very soft front springs while still giving a feel to the driver of the tires into the trakc or road. Stiff springs may push the tire into the road very hard but not for a long time where soft sprngs push the tire into the road longer but not very hard so there is a happy medium to be found there and that is by building jacking force into the front end geometry. A very good front end geometry program to look into is performance trends RC calculator. you can play with RC, instant centers, pick up points, springs, all kinds of stuff.