Originally Posted by TPIJeep
Crude way but it should work. I used my race car scales but a good bathroom scale should do it. With floor jack lift truck up. place spring between bumper and scale. slowly lower truck on spring till you get 1 inch of compression read scale. Thats the rate. If you max out scale compress only 1/2" and double weight reading. This should get you in the ballpark.
Oh and if it shoots out it hurts...
I will try this, and hopefully not kill myself.