Originally posted by rcspeedo
I understand that :
High R/C = less roll = less grip
Low R/C = more roll = more grip
But would'nt a more parallel upper link to the lower arm have a lower R/C compared to the upper link being more angled on the inside point.
When you lower the inside connection point of the upper link this raised the roll center and decreases roll and thus grip at that end of the car.
Likewise when you raise the inside connection point of the upper link this lowers the roll center and increases roll and thus grip at that end of the car.
However, Once you raise the inside connection point of the upper link so that the upper link is past being parrallel to the lower arm, then the camber actual goes positive when the suspension is compressed, which can take away grip mid and late corner. This can be a good thing or a bad thing depending on what you want the car to do.
When the upper link is parrallel or less than parrallel, the shorter the link the more camber change you will get when the suspension is compressed, which can help keep a larger contact patch during cornering for the outer tire and thus more grip. So in addition too using a low roll center to gain grip, you can also use a short upper link. This is important to remember because if you go to far with lowering the roll cente to gain grip you risk flipping the car and/or the car takes too long to transition from left to right (i.e. lazy).
hope that helps.