Quote:
Originally Posted by tsk94
This actually isn't entirely true (what I said).
Roll stiffness, specifically roll couple distribution, is what ultimately determines the handling balance in the steady state. The first step you, or someone, should always take to improve grip is going to a stickier tire. If that's out of the question, perhaps for due to rules mandating you run a particular tire, then the next step is to play with the roll couple distribution and wheel rates. This is amount of roll stiffness the front of the car has, relative to the rear. Increasing the rear roll stiffness (relative to the front) is what will get rid of understeer in the steady state. This can be down by softening the front springs or bars or stiffening the rear springs or bars. There is actually some published research indicating that stiffening the rear (via spring rate), relative to front, results in improved lateral acceleration - holding the setup on the car otherwise unchanged.
With that being said wheel rates and frequencies are also very important to consider as well. For the most part, almost everyone on the E9X chassis is running VERY front-biased spring rates. This leads to wheel rates and frequencies that are much higher in the front compared to the rear. In short, the effect of this is a car with the tendency to understeer more, a lot more, in the steady state. Now obviously there are other elements of suspension and alignment setup that can help mitigate this problem, but starting with the proper spring rates seems to be the best starting point.
Of most M3 track cars/builds I've seen on this forum, it seems like OG Shark is one of the few that's running spring rates that are even remotely close to being 'balanced' in terms of wheel rates and frequencies. Most, including myself, are severely front-biased - leading to a natural steady state handling balance of understeer.
This post is getting a bit long-winded so I'll cut it here, I mainly wanted to clarify my post from earlier to prevent misinformation from being spread. I'm in the process of completely reworking my spring rates (and thus wheel rates and frequencies) for next season to test this for myself and plan to start a thread outlining the mechanics in more detail and begin a more in-depth discussions.
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Yea, this is where I'm at as well. Cheers for spending the time to put it all into words!