This car has a front MC that is too far to the right of centerline for a flat asphalt track, stiff front springs and the rear spring split is too much. The roll angles are 1.8 degrees different and that makes for a very unbalanced and inconsistent setup. This car might be fast for a few laps, but in the long run, the lap times will fall off quite a bit.
These changes will balance the car while still providing sufficient bite off those flat corners. A high cross weight percent range works best to help with exit performance.
1.Change the front spring rates to: LR = 350, RF = 325 for conventional setups or under 250 for BBSS setups.
2.Change the LR spring to: LR = 185 (the split is reduced to 15 pounds vs. the original 25 pounds) for conventional or run a 175 LR and 250 or more in the RR for BBSS setups.
3.Raise the Panhard bar to: 9.50/10.75 for conventional or lower it to 9.00/9.50 or less for BBSS.
4.Move the dynamic MC width to the left to end up at 2.0 inches right of centerline.
5.Use a high cross weight range (more equal to the left side weight percentage).
The reverse spring split on the front helps the car on entry to the corners. If we were to run a stiffer RF spring than the LF, the car would begin to roll to the left on braking into the corners because of the softer LF spring and then as the car continues to drive further into the turns, the front must reverse and roll to the right. This gives the driver a very uncomfortable feeling and can best be described as a "flip-flop" sensation. When we change to running a stiffer LF spring, then as we brake into the corner, the car will begin to roll the same direction as we normally would see at mid-turn. The transition is smooth and the driver will have more confidence on entry.
The rear spring split, with the softer RR spring helps promote traction in the rear by loading the cross weight percent as weight is transferred to the rear upon acceleration. This is considered old school nowadays, and almost no one runs a softer RR spring. What is common is a stiffer RR spring combined with softer front spring rates. This forces the LF down more so in the turns. The Panhard bar must be mounted low for this type of setup to allow the car to be balanced.
The Panhard/J-bar can remain relatively low because of the wider rear spring base that is a characteristic of these cars. On a solid axle rear suspension like we use in stock cars, the wider the spring base, the more resistance to roll the car will have at the rear suspension. So to balance this type of car verses a stock type of Late Model, we need to run a lower rear MC (which produces a longer rear moment arm) to compensate for the wider spring base.
The front MC change (moving the MC to the left) makes the front suspension 'feel" softer and more efficient and want to roll to a greater roll angle to exactly match the rear suspension's desired roll angle.
Many teams who mostly run the flatter tracks try to set up their cars the same way at the higher banked racetracks. With the BBSS setups, teams are unpleasantly surprised when their cars bottom out hard on the high banks. It doesn't take long for them to start installing much stiffer front spring rates at high-banked tracks.
The higher banking produces much more downforce and the arrangement of springs that works best on the flatter tracks won't work well at all on the high banking. The higher the banking, the worse it gets. Rear spring split with the LR stiffer than the RR cannot be used because the higher g-forces cause more downforce and magnify the effects of the spring split. This make the cars very unbalanced. The popular BBSS setups are great on the high banks due to their high RR spring rate that is already installed.