Take a board or a book (something flat and hard), a bathroom scale and a stick (2X2, 2X4, broom stick, ect.). Measure the spring and cut the stick 1 inch less than the length of the spring. Place the spring on the bathroom scale, then place the stick inside the spring, then place the board ontop of the spring and now slowly push down on the spring untill the board hits the stick. Now read the scale. Really simple and it gives you a pretty good idea of what the spring rate is.
!M!