step-out-- it feels like a useful term for a specific subset of "oversteer" where the wheel isn't close to breaking loose
snap-- obviously it's not the dampers snapping, it's the springs. My point was that if the dampers work with the spring, then a sway bar shouldn't be any different-- from the perspective of the shock/spring, wheel loaded or not, the effect is the same-- pressure on the spring. That the wheel itself is unloaded, is a good point I had not considered.
Firewall spring effect would be the closest thing you can imagine it referencing-- firewall's "spring rate" is not as stiff as stiffer springs+sway bar, and as a result ("end-links and chassis" for example) exhibit greater compression than with stock springs.
What would be a good rule of thumb re: sway bar stiffness "upgrades"?
Are you saying these guys at Hotchkis shouldn't have released this product?
1) Convention/terminology doesn't care what you think. Oversteer is oversteer. It can be mild and predictable like what you are experiencing, or it can be dramatic and unpredictable. Next time you get a little oversteer lift throttle and then step on the brakes and then tell me it's not close to losing traction (careful, this could cause your car to spin).
2) Wow, I shall try to address all the fallacies and incorrectness here... The springs, dampers, sway-bars, suspension, etc are all mechanically linked, so they all experience the same motion. The dampers do work with the spring similar to how they work with the sway bar. However, the damper can only control a certain spring rate. The coil spring and sway bar both contribute to the effective spring rate the damper must control (the wheel rate). After the sway bar gets twisted up in a turn and starts to unwind after the turn the damper is there to control this motion. However, if the ARB is too stiff, the damper can't slow down the suspension's motion properly. This situation is 'under-damped' and is very essentially the same as using springs that are too stiff for your dampers. But, because it is different than an underdamped suspension, many describe the feeling as the car 'snapping' back to center out of a turn.
3) So "firewall spring effect" is another way of saying "the chassis is too floppy." I wish you would just use the right terms for various phenomena, it would make life easier.
4) I am not familiar with the tC's chassis, I don't know what would be too stiff. I wouldn't go over 2.5x or 3x stiffer on principle. If you're asking "do you think an aftermarket company would make a product that is ill-suited and poorly designed for its intended application" then the answer is yes. There are plenty of companies that make shitty aftermarket suspension components without understanding good suspension design. It's possible a stiffer sway bar could work well if the chassis received substantial bracing.
Please look at what you know with a little bit of skepticism instead just assuming what I'm telling you is incorrect because it conflicts with your assumptions.
Once you stop trying to tune the car to be RWD and tune it the best you can for how it really handles you'll be in better shape
This. It sounds like you are trying to make a porky FWD car handle like a high-end sports car with cheap components and it isn't going to happen.