Cpt.America

iTrader: (52)

You're welcome.. and remember, you get the same but opposite "direction" of traction shift, when you apply the same roll center changes to the front... A lower front roll center will provide mover overall grip at the front (more steering), and therefor by comparison, less in the rear.

So i often get asked, "then why not lower the roll center front and back as much as possible all the time for maximum traction?". And there are two answers really.

1) it really depends on how much grip your track has.
2) The farther the car rolls, the farther the car has to UN-roll as well, which makes the car slower in transitions

so let's explore #1
No matter what material your track is made out of, the ultimate goal is to run the fastest lap time you can, right? So lets say for example that you are on a really slippery surface. The extra grip you get from a very very low roll center (lots of roll, and therefor, lots of tire load), might benefit your lap times more than the "laziness" induced by a low roll center hurts your lap time, giving you an overall faster lap.... So in that case, a super low roll center becomes the fast way around the track.

Lets say you are on a very high grip track, like slicks on tacky clay (my track) or carpet. The opposite may give you better lap times. With a TON of natural tire grip, if you run a low roll center, you may develop TOO much traction, and may just end up traction rolling every time you take a corner. Being on your lid is never the fast way around the track. So strategically raising your roll center both front and back to keep tire load off your outside tires (and ON your inside tires), is a way to fine tune how much side traction you develop in a corner. The fastest way around the track will usually be the most roll you can get, without having to fight traction rolling.

On a high traction carpet track, you can run a VERY high roll center, as you don't need to load the tires at all to get the proper amount of traction... the benefit of a high roll center, (and therefor a car that doesn't roll much) is a car that can transition from right to left very quickly, and very stablely. (is that a word?)

The other thing to keep in mind, is running a lower or higher roll center on one end of the car compared to the other. This is used to bias traction towards one end of the car. So if you are looking for a little more steering, and you are already using ideal tires/inserts/camber and weight distribution, running a lower roll center in front (compared to rear) will give more steering, and less rear traction, and vice-versa if you run a lower rear roll center, than the front.

You can also induce more or less roll by how stiff of a spring and oil you are using in your dampers. The benefit of starting will roll center, is that roll center changes wont change how the car jumps, lands, and goes over bumps. So for example, lets say you wanted more roll... if you change to really soft springs and oil, you WILL get more roll, but it might adversely affect the car over bumps, or landing large jumps... where as roll center changes will not.

I hope that makes sense!

-cpt.