Originally Posted by
MantisWorx
Try raising the rear roll center, i have been meaning to CAD up the rear geometry just havent had the spare time to do it. Ok so i just sketched the rear geometry out on a piece of paper and there is no real roll center??? because of the angle of the lower arm the upper arm will never cross its path! I am going to draw it up and post later tonight. You want to try and get the arms as close to parallel as you can so this means the upper inside link needs to be spaced down ALOT!! I did this on my car and it works wonders. I think this is one of the reasons the car acts kinda funky with settings not only do you not have a true front roll center (king pins) and the rear roll center is somewhere in lala land. Using a rear only sway bar is always going to have a tendency to lift the inside front tire which leads to traction rolling. Try tuning your car without the rear sway bar or a very light one.
Just an update.
I moved the upper link to the furthest inboard hole on the rabbit rear arms to lengthen the link and spaced the ball stud down 1.0mm to get the arms parallel and it made quite a difference. The car no longer wanted to traction roll. I then pulled the rear sway bar off and the rear of the car started to rotate through the turns even better. To my surprise the inside front tire was very planted all night even as traction came up. Only other change was going up one step from the softest 201 springs.
Car still isn't perfect. I'm still scrubbing speed in the turns but its much better and much more consistent. My previous best deviation was 0.7x and I got it down to 0.48. Car felt very good all night long. I know I'm leaving a few tenths in the turns. I was thinking of only using traction compound on half of the rear tire. Any other ideas?