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Motion Ratio Formula:
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Motion Ratio in Suspension is the ratio of the angular displacement of the steering axis to the angular displacement of the wheel. It represents the relationship between spring/shock travel and wheel travel in a vehicle's suspension system.
The calculator uses the Motion Ratio formula:
Where:
Explanation: The motion ratio indicates how much the spring or shock moves relative to the wheel movement. A ratio of 1:1 means the spring/shock moves the same distance as the wheel.
Details: Accurate motion ratio calculation is crucial for suspension design, spring rate selection, and optimizing vehicle handling characteristics. It affects wheel rate, suspension stiffness, and overall vehicle dynamics.
Tips: Enter spring/shock travel and wheel travel in meters. Both values must be positive numbers greater than zero for accurate calculation.
Q1: What is a typical motion ratio range for vehicles?
A: Motion ratios typically range from 0.4 to 1.2, depending on the suspension design and vehicle type.
Q2: How does motion ratio affect spring rate?
A: The effective wheel rate is calculated as (spring rate) × (motion ratio)². A lower motion ratio reduces the effective spring rate at the wheel.
Q3: Can motion ratio change during suspension travel?
A: Yes, in many suspension designs the motion ratio is not constant and changes throughout the suspension travel due to linkage geometry.
Q4: Why is motion ratio important for suspension tuning?
A: It helps determine the appropriate spring rates, affects progressive/regressive suspension behavior, and influences how the suspension responds to road inputs.
Q5: How is motion ratio measured in practice?
A: Typically measured by comparing the vertical movement of the spring/shock mounting point to the vertical movement of the wheel center while the suspension articulates.