Some people doing their own custom suspension setups (such as solid axle swaps – aka SAS) have researched to find the coil spring rates of various coils to use in their Ford Ranger. We have gathered that information and placed it here so it’s in one place.
For reference, the stock Ford Ranger coil spring rate is 500 PPI (Pounds Per Inch)
Skyjacker 4″ coils = 450 PPI
Skyjacker 6″ coils = 410 PPI
Skyjacker 8″ coils = 410 PPI
Skyjacker Cherokee 6″ coils (pt# JC60F) = 240 PPI (solid axle)
Jeep XJ coils = 180-220 PPI
Early Bronco 5.5″ Deaver coils – 340-360 PPI (solid axle)
Deaver 4″ Superflex coils = 350 PPI (solid axle)
Deaver 6″ Superflex coils = 300 PPI (solid axle)
Rough Country 4″ coils = 434 PPI
Trailmaster 4″ coils = 445 PPI
Superlift 4″ coils = 530 PPI
Jeep Rancho 6423 coils = 240 PPI (solid axle)
Rusty’s Offroad coils = 150 PPI
James Duff 3″ Progressive-rate coils = estimated 400-500 PPI (conflicting, dual rate #)
How Can I Calculate the Spring Rate of a Coil?
If you have a coil spring and don’t know what it’s spring rate is, you can calculate it once you know:
Coil Spring Wire Diameter (CSWD) – How thick is the coil wire? The number must be entered as a decimal. To convert a fraction to decimal, click HERE.
Number of Active Coils (NOAC) – Coils that are free to move, not the coils seated. 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.
Coil Mean Diameter (CMD) – The diameter from center to center of the coil wire. Measure the diameter of the coil from wire center to wire center. If you know the coil is .5 inches thick and the outside diameter of the coil spring is 5-inches, then the Coil Mean Diameter would be 4.5-inches.
Jim Oaks is the founder of TheRangerStation.com, the longest-running Ford Ranger resource online since 1999. With over 25 years of hands-on experience building and modifying Ford Rangers — including magazine-featured builds like Project Transformer — Jim has become one of the most trusted authorities in the Ford Ranger off-road and enthusiast space. In 2019, he was loaned a Ranger FX4 by Ford Motor Company to test and document across the TransAmerica Trail. Jim continues to inspire and guide Ranger owners around the world.