Coilover Spring 10in x 2.5in 300/750 Prog

The SWIFT SPRINGS Coilover Spring 10in x 2.5in 300/750 Prog is a progressive-rate coil spring engineered for drivers who demand precision suspension tuning and improved handling dynamics. This spring is ideal for street performance builds, track-focused vehicles, and custom suspension setups where ride quality and cornering control must coexist. Progressive coil springs like this are essential when you need compliance over bumps at low speeds but dramatically increased stiffness under hard cornering or braking loads—a characteristic that makes them the go-to choice for serious suspension enthusiasts and fabricators.

Built from high-quality steel with a black powder-coat finish for durability and corrosion resistance, this coilover spring features a conventional barrel design and a 2.5-inch inner diameter that integrates seamlessly into most modern coilover assemblies. The 10-inch free length accommodates full compression and extension cycles without bottoming, while the dual-rate spring constant—300 pounds per inch initial rate and 750 pounds per inch progressive rate—delivers a smooth initial response that transitions to firm support under load. This progressive characteristic reduces harshness on rough pavement while maintaining the high spring rates necessary for performance-level body control and anti-squat geometry during acceleration.

This spring is best suited for enthusiasts building or upgrading coilover kits on import performance cars, drift platforms, autocross competitors, and street-strip vehicles where suspension geometry matters as much as spring rate. Installation requires proper suspension knowledge or professional alignment afterward, as changing spring rates will alter your vehicle's ride height, center of gravity, and suspension geometry. The 7.39-pound weight is typical for a spring of this size, making it suitable for weight-conscious builds. Always pair this coilover spring with compatible dampers and matching springs for the remaining corners to ensure balanced handling and predictable suspension performance.