18in C/O Spring Platinum 3.5in ID

The 18in C/O Spring Platinum 3.5in ID by EIBACH is engineered for serious suspension tuning and performance vehicle modifications. This coil-over spring serves as the backbone of modern lowering and adjustable suspension systems, allowing you to dial in ride height, spring rate, and chassis geometry for track days, autocross, or aggressive street duty. Whether you're building a dedicated race car or upgrading a daily driver for improved handling and aesthetics, this Platinum-grade spring delivers the engineering precision that separates professional builds from bolt-on aftermarket parts.

EIBACH's Platinum line springs feature cold-wound, stress-relieved steel construction optimized for consistent load rates and minimal rate variance across the spring's travel window. The 3.5-inch inner diameter (ID) design integrates with standard coil-over shock bodies, while the 18-inch length provides the compression range necessary for multi-stage lowering setups and custom damper configurations. The Platinum rating denotes superior material quality and fatigue resistance compared to standard springs, translating to longer service life under sustained high-performance use, repeated compression cycles, and demanding track applications where spring degradation is a critical failure point.

This spring is ideal for suspension builders, professional mechanics, and experienced enthusiasts fabricating complete coil-over systems or refurbishing existing setups. The 3.5-inch ID makes it compatible with most aftermarket coil-over bodies and OEM shock platforms that have been converted to adjustable damper configurations. Installation requires proper spring compression tools and technical knowledge of suspension geometry; improper seating or mismatched spring rates can compromise vehicle handling and safety. Pair this spring with matched dampers and adjustable perches to unlock full tunability for corner weighting, anti-roll center tuning, and dynamic suspension optimization.