Coil Spring Rate Formula: 11,250,000 - Torsional Modules For Steel (Constant).

400 lb/in = 7.1 kg/mm. 650 lb/in = 11.6 kg/mm. Roughly 1 KG/mm is equal to 55.997 LBS/in. As you can see from the accompanying chart, courtesy of QA1, the correction factor increases as the angle increases to the point that if a coilover is mounted at 45 degrees… CSPWD - Coil Spring Wire Diameter (How thick is the wire?). Not coils seated.

This measurement helps determine the “force angle” and resultant spring force applied to the control arm. 500 lb/in = 8.9 kg/mm.

In most cases, this will be somewhere between 75 degrees and 90 degrees.

and above for a more significant transition. It may be that 1/2 of the top and bottom coil is seated causing a spring with 8 coils to have the distance of 7 free.) While running the same spring top and bottom will still give you a transition, we recommend (if possible) a 50 lb. 600 lb/in = 10.7 kg/mm. The greater the angle of the spring, the stiffer it will need to be to support the weight of the car. 450 lb/in = 8 kg/mm.

range and a 100 lb.

NOAC - Number Of Active Coils (Coils that are free to move.

8 - Constant. Here’s a few quick charts: 700 lb/in = 12.5 kg/mm. 550 lb/in = 9.8 kg/mm.

heavier lower spring in the 100 to 300 lb.

Most conventional springs and many strut suspensions are very close to 90 degrees, and 90 degrees can be used for the angle. A coilover with a 10” 225 lb.

heaver spring for spring rates 400 lb. spring that is installed at 0° straight up … Easy way to remember is 1 KG/mm = 56 LBS/in. For dual rate coilovers you will need to multiply the spring rate calculated above by two to get the required spring rates.