If you REALLY want to nail down a spring rate...take the time to get some measurements and weights...and use this calculator:
http://www.ridetech.com/tech/spring-rate-calculator/
Yes, the images show it to be for coilovers...pretend they are regular coils...the calculation concept is still valid. DON'T take a coilover recommendation and think it will carry over to a standard coil...the mounting positions can be different. Measure and weigh.
As a second choice, use the extensive library of vehicle weights on our website to guesstimate your car's weight
http://www.ridetech.com/tech/coiltech-2/
...and still take your measurements.
THEN...contact a vendor who deals with circle track springs...they will likely have a selection of spring rates that will serve your purpose. These guys might be able to help:
http://www.speedwaymotors.com/Shop/C..._Diameter:5.00
Yeah, I know we won't be able to sell you anything this time...that's OK...say something nice
