Tune coilovers with quick ride height estimates today. See perch travel, turns, and drop values. Built for practical chassis setup checks and workshop planning.
| Corner | Current Height (mm) | Target Height (mm) | Motion Ratio | Thread Pitch (mm/turn) | Spring Rate (N/mm) | Perch Movement (mm) | Turns |
|---|---|---|---|---|---|---|---|
| Front Left | 140 | 125 | 0.70 | 1.50 | 60 | -10.50 | -7.00 |
| Front Right | 141 | 126 | 0.70 | 1.50 | 60 | -10.50 | -7.00 |
| Rear Left | 133 | 128 | 0.82 | 1.25 | 52 | -4.10 | -3.28 |
| Rear Right | 134 | 129 | 0.82 | 1.25 | 52 | -4.10 | -3.28 |
1) Ride height change
Ride Height Change = Target Ride Height − Current Ride Height
2) Perch movement
Perch Movement = Ride Height Change × Motion Ratio
3) Turns required
Turns Required = Perch Movement ÷ Thread Pitch
4) Wheel change per turn
Wheel Change Per Turn = Thread Pitch ÷ Motion Ratio
5) Approximate spring force change
Spring Force Change = Spring Rate × Perch Movement
This calculator uses motion ratio as spring travel divided by wheel travel. Keep that definition consistent when entering values. Measure ride height from the same fixed points each time for repeatable results.
Ride height changes affect balance, clearance, and suspension geometry. Small perch changes can produce noticeable chassis movement. A measured adjustment helps you avoid random trial and error. That saves time in the garage and supports more repeatable setup work.
This tool converts a target ride height change into perch movement and collar turns. It uses thread pitch and motion ratio. That makes it useful for coilover tuning, corner setup checks, and workshop planning. You can also estimate the wheel change created by one full turn.
Motion ratio links wheel travel to spring or damper travel. The same perch movement will not create the same wheel change on every suspension design. MacPherson struts, double wishbone layouts, and rear multilink systems can all behave differently. Accurate motion ratio input improves the estimate.
Use a flat surface. Keep tire pressures consistent. Roll the vehicle forward and backward to settle the suspension before measuring. Measure from the same fixed points each time. Many builders use wheel center to fender lip because it reduces tire diameter error during setup comparisons.
Spring rate is optional. It gives an approximate spring force change from the perch movement. That value is useful for engineering review and setup notes. It is still an estimate. Final ride height depends on suspension friction, bushing compliance, corner load, and vehicle settling after adjustment.
Always remeasure after every change. Make small moves, then settle the chassis again. Record each corner. Match your notes with alignment and damper settings. A simple ride height worksheet improves repeatability and helps track what actually made the car better.
Measure from the same fixed points every time. Wheel center to fender lip is common. Ground to pinch weld can also work on a level surface. Consistency matters more than the chosen method.
Enter the suspension motion ratio defined here as spring travel divided by wheel travel. Use the value for the specific corner or axle you are adjusting. Front and rear values often differ.
One turn moves the perch by the thread pitch, not the wheel by that amount. The suspension linkage changes the final wheel movement. That is why motion ratio is included in the formula.
Yes. If the target height is higher than the current height, the result shows a raise. If the target height is lower, the result shows a lowering adjustment and the needed perch direction.
No. It is an engineering estimate based on spring rate and perch movement. Real results can vary due to friction, preload condition, settling, and suspension geometry through travel.
Not always. Thread pitch may match, but motion ratio and spring rate can differ by axle or corner. Measure and calculate each location separately when you want the best setup accuracy.
Suspension parts need to settle after turning the collars. Tire position, bushing wind-up, and surface variation can shift the measured value. A second measurement confirms the actual chassis change.
No. This calculator helps estimate perch changes. It does not replace a proper alignment or corner balance session. Use it as a planning tool before final chassis tuning.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.