12:05 Garage- ’70 Duster build

mopowers said

Thanks. I hadn't seen that. I'm going for something on the softer side for my strip-oriented combo. Right now, I've got 450 lb/in coilovers - which based on that table - look to be equivalent to a 1.14" bar w/ the 0.77 ratio. That explains why it's so stiff.

If I'm going for something closer to a .870" bar, I'd need a 150-175 lb/in coilover. Am I doing the math right?? Seems super soft.

Click to expand...

So

Wheel Rate = Spring Rate * (Motion Ratio^2)

The HDK has a motion rate of .807, so yeah a 450 lb/in spring yields a 293 lb/in wheel rate.

If you wanted a wheel rate more like 120 lb/in and you had the same ratio you’d need a 184 lb/in spring.

If your motion rate is .77 then your 120 lb wheel rate would mean a 203 lb/in spring.

As far as seeming soft, a 300 lb/in torsion bar is 2.5x stiffer than a factory .87 bar (120 lb/in), so it’s a pretty similar change.