Sway-Away spring rate calculator


Well-Known Member
Has anyone used the spring calculator on the swayaway website? The numbers I got for the front rates seemed accurate, but the rears seemed WAY too high. I am trying to figure them out for an equal length ibeam front and a 4-link rear, on a standard cab short bed F150 chassis.

If anyone else has any suggestions for calculating spring rates, I would appreciate it.

- Andy

94' Lightning Prerunner (in-progress)


Well-Known Member
There are some things to keep in mind. If your shock/coil spring is mounted half way out on the lower control arm as opposed to right on the axle, the spring rate needs to doubled for the leverage and doubled again for the travel. That’s 4 times what it would be if mounted right on the axle. Also, short travel needs a much higher rate than long travel. Twin I beams have the spring mounted much farther out than half way.

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