Metric Four Car On High-Bank Tracks
So I think I've read everything you've ever written on moment centers—at least twice. I race a Metric Monte Carlo in a Sportsman class at the Rockford Speedway in northern Illinois. It's a quarter-mile 20'ish degree banked track.
My main question is what are the tradeoffs related to rear spring split—roll angles—and forward bite coming out of the corner? The 50-pound spring split gets quoted often in regards to overcoming the high rear MC of the Metric four-link. When I model it in my setup program I get some high roll angles, around 5 degrees, with the 50-pound split.
It seems that the split is needed more to tighten the car on acceleration off the corner. Do you see a trade off here? For a 20-degree bank track the program advises to keep the roll under 1.5 degrees. To do this I pretty much have to even up the springs, say 175s in both the LR and RR. I haven't actually tried it yet but I think I'm gonna lose what precious little bite I have now.
My second question is, is it worth it to try the low crossweight setup when I'm trying to solve a chronic loose off (no bite) condition with my 55-percent cross setup? I feel guilty not following your advice there. I've read it probably a thousand times. It seems counter intuitive to shift weight from the LR to the RR when that happens all by itself.
The recommendation for a spring split, with a softer RR spring, is mostly useful for running on flatter tracks. With the high banking of Rockford, and I have been there a couple of times, you do not need to do that.
With the high banking there comes a high amount of mechanical downforce. This causes more roll due to spring split and the softer RR spring will definitely tighten the car too much.
What you now have is probably a tight/loose condition due to the unbalanced setup. Once you stiffen that RR spring and make it equal to or even stiffer than the LR, then the loose will probably go away. So, trust that when you balance the setup, you'll have plenty of bite off the corner.
Usually, we don't need to run the high crossweight for high banked tracks. You have a greater than 50 percent rear weight percent since you need to run the 55 percent low range. I would try to move the car close to a 50/50 front to rear percent. Yes, your crossweight percent will need to be lower that way, but trust that it will work.