Oh, and one other thing... James alluded to this... Spring rate vs. wheel
rate. You have to measure the geometry of your lower control arm (or upper
if you had some weird suspension where the spring was actuated off of the
upper arm...) Measure the distance from the arm pivot point to the outer ball
joint, and pivot point to the point where the strut contacts the lower arm (or
centerline of the spring if it's offset). Let's say you have a 10" long
lower arm, and the centerline of the spring contacts the arm 8" out from the
pivot. You have a motion ratio of .8. Square that and you get .64. Take
that
squared number times your spring rate, and that's your wheel rate. So, if
you have a 500 lb spring, you have a 320 lb. spring rate.
One of the reasons big 'Murrican cars use such high spring rates is the
motion ratio of their SLA suspensions. I think some of them are .5 or less.
Square that and you get .25, so a 2000 lb spring rate gives them a 500 lb.
wheel
rate...
Charlie
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