spring rate calculator

All measurements are in mm

Spring name Wire gauge (diameter) Spring diameter Number of active coils (see chart) Young's Modulous (leave blank for standard)	Effect of end treatment.
		Plain Ends	Closed Ends	Plain Ends Ground	Closed Ends Ground*

	Active Coils, N_a	N_t	N_t-2	N_t-1	N_t-2
	Typically, either closed ends or closed and ground ends are specified due to the greater area of contact between the spring and its base.

Name	Wire gauge	spring diameter (center of wire)	number of coils	Modulous of...	Spring rate (kg/mm)	Spring rate (lb/in)
41mm RaceTech .95	5.14	29.6	29.25	8420	0.96	53.7
41mm RaceTech .90	5.09	30	29	8420	0.9	50.3
41mm RaceTech .85	5.01	30.17	27.33	8420	0.88	49.2
41mm RaceTech .85 (2)	4.94	30.25	26.5	8420	0.85	47.5
41mm RaceTech .85 (3)	4.90	29.6	26.66	8420	0.87	48.7
41mm RaceTech .80	4.87	29.9	28.1	8420	0.78	43.6
mod'd F4(total)	4.85	32.67	21	8420	0.79	44.2
mod'd F4(final)	4.85	32.67	16	8420	1.04	58.2
43mm mystery F4	5.00	31.38	23.5	8420	0.9	50.3
'03 R6 spings	4.80	33.13	17	8420	0.9	50.3
'01 SV stock	4.75	30.51	25.875	8420	0.72	40.3
Traxxion, .90, for SV	4.78	29.70	22.125	8420	0.94	52.6
Penske/traxxion supplied shock spring supposed to be 650lbs/in	12.32	70.82	7.375	8420	9.25	517.9
Ohlins shock/spring labled 1093-54/140 058	12.36	70.13	6.25	8420	11.39	637.8
Hyperco, 1,300 lbs/in	14.25	72.685	4.6666	8420	24.21	1355.6


         G * W^4
K=G = ----------------
        8 * N * D^3


K = Spring rate
G = Youngs modulus (stiffness), depending on units
W = Wire diameter
D = coil diameter (center of wire to center of wire)
N = number of turns