NEW REPLACEMENT COILS SPRINGS CAN BE SHORTER THAN SAGGED ORIGINAL SPRINGS.
We get a lot of calls from customers who have ordered replacement coil springs to replaced sagged original ones in a vehicle, who have opened up the packaging and removed the new Cobra coils and then compared the free heights of the new springs with the old ones.
Upon doing this they discover that the new coils are shorter than the sagged ones, yet the reason they wanted to replace the coils in the first place was to raise the vehicles ride height. How can the shorter springs achieve this?
The simple answer is that we are dealing with a ride height that we want to achieve with the coil springs under load, and the distance that the new coil will compress to with the same weight or load applied to it is much less than the old one.
Massive increases in spring rate can be gained by only a small increase in the wire diameter, other factors determining spring rate include the mean diameter of spring, the amount of material and the number of active coils.