Physics Help Forum Dynamic Spring Rate formula

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 Sep 24th 2015, 08:36 PM #1 Member   Join Date: Jul 2014 Location: KY Posts: 41 Dynamic Spring Rate formula Hi guys, I am trying to find a formula to calculate dynamic spring rate. Here is what I have to work with. Spring rate: 200# Static on the car: 1000# Spring travel: 3" Dynamic Load, car going through turns, 2200#
 Sep 25th 2015, 10:01 AM #2 Physics Team     Join Date: Jun 2010 Location: Naperville, IL USA Posts: 2,271 Not sure what you mean by "dynamic spring rate." If the spring is rated at 200 lb/in, that's what it is. Keep in mind that there are other components besides a spring that influence how much the car leans in a corner - for example anti-sway bars tie springs on both sides of the car together. But if the increased compression from a static 1000 pound load to a dynamic load of 2200 pounds is 3 inches, then the spring constant is (2200-1000)/3 = 400 pound/inch.
 Sep 25th 2015, 02:44 PM #3 Member   Join Date: Jul 2014 Location: KY Posts: 41 Hi Chip, maybe I didn't state the question correctly. The spring rate is 200#, when I put it on the car and put the car on the scales the wheel weight at that time is 1000#. When I use a machine, GaleForce, to compress the shock the 3" of travel that I have I get a reading of 2200#. I was wondering, since I borrowed the GaleForce, if there was a way to calculate this without the machine. Hope this clears the question up. Thank you.
 Sep 30th 2015, 05:45 AM #4 Physics Team     Join Date: Jun 2010 Location: Naperville, IL USA Posts: 2,271 Does the Galeforce machine apply a load to the shock and associated spring only? Or does it apply a load to the car? If the latter - do you have the resulting weights for the other three wheels? I'm guessing that this is another type of corner balance problem. If it applies a load directly to the shock, then the compression of the spring would be impacted by the geometry of the suspension. So yes, I think it can be calculated if you can define the suspension geometry. Last edited by ChipB; Sep 30th 2015 at 01:40 PM.

 Tags dynamic, formula, rate, spring