Enter your Corner Weight, Unsprung Weight, Dimension A, Dimension B, Coilover Angle, Wheel Travel, and Target Wheel Rate to calculate the Required Spring Rate for your coilover setup — plus your Motion Ratio, Effective Wheel Rate, and Natural Frequency so you can dial in your suspension with confidence.
Required Spring Rate
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Motion Ratio
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Effective Wheel Rate
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Natural Frequency
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Motion ratio is the relationship between wheel movement and spring/shock movement. It affects how spring rate translates to wheel rate. A lower motion ratio means the spring rate needs to be higher to achieve the same wheel rate.
Dimension A is measured from the control arm pivot point to directly under the spring centerline. Dimension B is from the pivot point to the ball joint centerline. Use a measuring tape and ensure the suspension is at ride height.
Spring rate is the force required to compress the spring one inch. Wheel rate is the force at the wheel required to move it one inch vertically. Motion ratio converts between these two values.
Angled coilovers reduce the effective spring rate because the spring doesn't work directly vertically. The calculation accounts for this angle to determine the actual spring rate needed.
Street driving typically uses lower spring rates (100-200 lbs/in wheel rate) for comfort. Racing applications use higher rates (200-400+ lbs/in) for better handling and reduced body roll.
Use corner scales or visit a racing shop with scales. Alternatively, divide total vehicle weight by 4 and adjust for weight distribution (front/rear bias and left/right balance).