wstar

I still don't think aero is the answer to an over/under-steer imbalance problem at this point. You don't want a setup where the suspension is setup is out of whack without aero and only becomes balanced under aero loading, because again the aero effect is non-linear and is basically non-existent at the low speeds you'll be hitting while rotating through tight corners (at which point the car will still be skating around like however it is now).

I've driven my car in the past in the kind of state you're talking about, where I had the rear half of the interior completely gutted but it was mostly stock from the seatbacks forward, and no cage. Mine was like that for several months at one point. It made suspension tuning a little trickier to keep the car from oversteering too much, but even when it felt wrong to me it was still totally drivable and controllable, and spins/offs were rare and totally my fault. At the time I ran 275 front tires on 10's and 295 rears on 11's and that was enough stagger to compensate (and using the soft setting of the Hotchkis rear bar). The fact that you have these huge spring rates as a starting point could be coming into play as well; you may just have to buy some weaker rear springs for now until you finish the rest of the car's setup.

When you say things like "I can't touch the throttle without spinning out", it's hard to interpret what that really means. Does that mean you're entering corners too hot (under-braking) and thus not leaving enough speed on the table to apply throttle at track-out to stabilize the suspension? It's hard to imagine, even in its current state, that the car is so oversteer-crazy that you can't use the throttle on track-out at all. I didn't miss somewhere that you put forced induction on the car, right? Even if the car is a bit too over-steer happy, you should be able to still use light throttle and correct with steering angle and adjust your reference points, etc and get the car to drive.

Earlier on in the first post, you mentioned that situationally sometimes you got massive oversteer, and other times the car simply drifted straight sideways. That sideways drift is what should happen in a reasonably-balanced car as you throttle up at track-out. Going a little "loose" and over-steery intentionally you still have that sort of behavior, it's just the angle of the slide changes and the rear slips out a little faster than the front does at the limit, but both ends should be slipping to some degree. It's a small degree, though, not a drifter-type slide. Maximum traction on most tires you'd ever use on a track occurs around the ballpark of 5-10% slip angle. The traction of the tire builds progressively as you add more lateral g's up until it begins to slip, then keeps building for those first few percent of slip. After you cross over that peak and keep slipping at harder angles though, the traction on most tires falls off a cliff pretty dramatically, which is where you start losing control of the car. Generally speaking the grippier the tire, the more spiky the traction peak is (meaning you have a much smaller optimum window to play in before you hit that dramatic dropoff in traction).

There's no such thing as money aside in this hobby, unless you're a billionaire or have one sponsoring you But still, I really like the square setup, and I totally think that with the right damper/spring/bar setup you could run square even with a weight-distribution problem in the rear. Going back to something I mentioned above: if the car really is way too oversteery, the most likely fix is reducing rear spring rate to get more weight transfer into your lighter rear-half. Try completely removing the rear sway and see if that helps as a test.

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