Roll Centers revisited

[jdearhart]

What are everyones thoughts on roll centers? Should they be measured and calculated at "x" high and "x" to the left as the performance trends (

http://www.performancetrends.com

) software does? Or should they be calculated as mechanical downforce and not worry about the lateral or vertical location as the Brown Performance Engineering (

http://www.brownperformanceengineering

) software does? This is for a Nascar style latemodel, 3100 lbs., left turns only. Any help would be appreciated.

 

[GregLocock]

Whatever they are, they aren't mechanical downforce. Oh unless you mean jacking force on the outside wheel (I'd have to think about that).

The performance trends approach is the traditional kinematic construction. I'm never very sure what its proponents think it is measuring, so far as I can tell it is a measure of the instantaneous camber gain (handy in its own right), and is vaguely related to the force based roll centre, which at least has a physical meaning, even if, again, I'm not really sure that it does what people think it does.

I'm also a little puzzled by what FBRC proponents think the lateral component of its position actually signifies.

What I do know is that if I raise both types of roll centre we get better steering, apparently, subjectively. I have yet to see any data that reliably documents a consistent change in behavior, but it is practically difficult to set an IFS/IRS car up with different roll centre heights and everything else unchanged.








Cheers

Greg Locock

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