Hotchkis leaf issue, sits like 4x4.
Are we implying my car is going to settle over 4 1/2"?
It will compress the springs directly in proportion to the weight on them.
Lets say the spring rate on each leaf spring is 100 lbs force per inch. So that's 200 lbs/in for the pair.
Placing 200 lbs in the trunk directly over, or slightly to the rear of the axle will compress the springs one inch.
How much your springs will compress with your car can be predicted
if both the current and fully outfitted front and rear weights are known. The weight can be shifted around a bit by adjusting the torsion bars (simultaneously changing ride height). But the relationship between chassis hieght, spring rates and weight is most of it: Distance compressed(in) = weight (lbf) / spring rate(lbf/in)
On cars where springs don't act directly (coil spring suspensions), then wheel rate is used instead of spring rate.
The spring pack and suspension has some friction and may settle a bit and shocks can slow the settling as well.
edit: corrected the equation.
