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Author Topic:   Roll Center Height
dilbert
Dirt Roller

Total posts: 21
posted July 01, 2002 12:01 AM
Hey guys, got a dumb question--How do you find the front "roll center" height? I know what it is, but what if the "instant center" is way out to infinity? In other words the upper A-arm and lower A-arm are parallel or the ball joints are closer together than the pivot points on the frame?

justin
Dirt Maniac

Total posts: 167
posted July 03, 2002 06:57 PM
If you know what your instant center is for both the left front and right front you can find your roll center height. For example, once you find your your instant center for the right front, you need to draw a line from the center of the right front tire contact patch straight to your instant center, this is called your swing arm. Do the same thing for the left front, and where your two swing arms intersect is your roll center height. If your instant center is way out toward infinity on both sides I would think your roll center height is way too low. Do you have a lot of body roll in your car, usually a lower roll center will have more boldy roll that a higher one. I would say you want it about 3 or 4 inches above the ground. If anyone sees anything wrong with what I've said feel free to correct me.

Justin

dilbert
Dirt Roller

Total posts: 21
posted July 07, 2002 11:22 PM
Justin, thanks for the tip, I know what the term instant center means, but mine is out the opposite way that everything I have seen says it should be. In other words if I project pivot points inward, the lines separate instead of meet. What does this mean for roll center height? Should I project them (the swing arms) the other way (out)? The car actually handles pretty well without excessive roll, and I have a 1250 spring in the rf, so I'm wondering if anything maybe my roll center is too high instead of too low. Does anybody know, or am I thinking too much? Or maybe the car will never be "right"?

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