[Ron Sutton]

Originally Posted by mfain

Here's something for the racers in the crowd to comment on. Since my project track car is taking forever to finish, I bought a NASA Spec Ford Focus to build current track time in the interim. It is a full cage, SVT suspension, professionally built car - 2300lb s/146 HP on Hoosier R7s. I have worked the suspension until it is very neutral and, despite its low HP, is a very fast "momentum" car. Yesterday, at Wild Horse Pass in Phoenix, I took a fairly tight sweeper at 75-80 mph (on the edge). With the car being very neutral, I expected it to break loose at both ends if I exceeded the limit - it didn't. Instead it rolled 30 degrees (inside tires 3 feet off the track) AND the outside rear tire came off the ground 6 inches. The thing tried to "pole-vault" over the outside front tire which still had grip. Luckily I was exiting the sweeper and straightening the wheel. I stayed on the throttle (FWD) and the car came down hard with only a minor 2-wheel "off". Any thoughts other than the obvious CG height comments?

Pappy

Hey Pappy !

I suspect it is a combination of the CG being high and the front roll center being low ... maybe below ground ... and migrating far to the outside of the front tire ... which makes the moment arm (distance from CG to RC) be the lever that it is ... except the lever is causing the inside tires to lift.

In professional race cars, we work hard to make the front roll center migrate the opposite direction ... and migrate towards ... or past ... the inside front tire. We do this to work the inside tires mo'better ... and not lift them off the ground.

So ... even when you're not lifting the inside tires off the ground ... that car is not loading the inside tires much, if any.

Have fun & be safe !