Wheel Frequency

Wheel frequency takes into account spring rate, motion ratio, sprung and  unsprung weight and is calculated in Hz. A higher number means stiffer suspension, lower means softer. I am only just learning about wheel frequency and wanted to know how my suspension will be before driving it. First thing I did was disconnect my shocks and set the car at normal ride height. I picked a spot close to where the middle of where the wheel would be mounted such as the  middle of the dust cap on the front spindle or centre of the axle flange on the back. Then I carefully measured the distance from the dust cap or flange to the ground and wrote that number down. Then I measured the distance from where the shock mounts on the rocker arm (such as the rear one in the above picture) to where the shock mounts on the chassis and wrote that number down. Using a floor jack, I raised the suspension up a set amount, in my case 10mm, then measured the amount the shock mount moved. I could move the suspension another 10mm and measure the amount the shock mount moved again and see if the motion ratio changed. In my case, when the wheel moves 10mm, the shock moves 7mm.  My motion ratio is 10 divided by 7=1.428. I used a bathroom scale to find out my front unsprung weight and Google to find out my rear unsprung weight(half the total weight of a Ford 9" plus the weight of one wheel and tire). I have also had my car on scales so I know my corner weights. Using this online calculator http://www.racingaspirations.com/?p=292 I plugged all the numbers in and found out that my wheel fequencies are 2.68Hz in the front and 2.53 Hz in the rear. From what I can tell, these are good numbers to start with on an EMod car. Since my car looks to be a little understeery, I will add a sway bar to the back of the car to balance it out. These numbers could change when the car is all ready to run because my corner weights could be higher than expected. Also, I can change the numbers just by changing the hole that the pushrod and/or shock are bolted to. With a little research, you can find out the numbers for your car and see what changing to lighter wheels or changing spring rates will do to the handling.