Torsion Bars... Best Diameter for a Lowered Street / Autocross car?

AJ/FormS said

Same here. I even removed the shocks and the T-bars and the lower bumpstops,and cycled the steering, cuz I wanted to know. The Moogs were happy.
In the end, I raised my K, a half an inch higher off the tarmac, cuz with street tires and on the street it's no big deal, the car is just as much fun, because the tires are by far the limiting factor.
And because of potholes. Our city streets have potholes; lots and lots of them, and I occasionally hit one, and it's nice to have the extra suspension travel.
Plus I am 20 years older than when I first started ,lol, and them RX-7 seats ain't as cushiony as they once were,.

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The diameter of the torsion bar ultimately determines the minimum ride height you can run, you need to have enough travel left so the suspension doesn’t bottom out. The larger the bar the less travel you need to avoid bottoming.

Of course that’s not everything, suspension is always a compromise and you have to go with torsion bars that match the use of the car, roads it will be used on, the compounds of the tires etc. If you’ve got smooth roads and sticky tires you can go way bigger than if you’re running all seasons on rough terrain. And being tire limited is fine, the car is usually nice and predictable even if it’s a little “loose”. And if you get better tires it’ll rip with no other changes. Plus a little loose is more entertaining anyway :D.