Coil Spring - 2.5in x 9 400#

The Coil Spring – 2.5in x 9 400# (part number 9HT400) is a high-travel coil-over suspension spring engineered for demanding off-road and performance applications. This 400 lb/in spring rate component delivers the progressive load support needed in lifted suspension systems, custom shock applications, and heavy-duty vehicle setups where precision spring performance directly impacts ride quality and handling stability.

Specifications confirm this spring's suitability for coil-over installations: a 2.5-inch inner diameter accommodates standard coil-over shock bodies, while the 9-inch free length provides the compression travel range required in modern suspension geometry. The 400 pound-per-inch spring rate represents a medium-firm specification—stiff enough to control vehicle weight and chassis movement during articulation, yet compliant enough for daily driving comfort on moderate terrain. Steel construction with silver powder-coat finish resists corrosion from moisture and road salt, extending service life in harsh environments. Each spring weighs 3.64 lbs and ships individually, allowing buyers to purchase matched pairs or upgrade individual corners as needed.

This spring serves builders and enthusiasts upgrading truck and SUV suspension systems, prerunners tackling rough terrain, and custom fabricators designing or repairing coil-over shock assemblies. The 400# rate performs well with vehicles in the 4,000–6,000 lb weight range and pairs effectively with mid-range dampers to achieve balanced suspension tuning. Proper spring selection depends on total vehicle weight, ride height target, and shock absorber valving—confirming correct spring rate before installation ensures predictable suspension behavior and prevents bottoming or excessive compliance.

Coil spring rate selection is critical in suspension design. A 400 lb/in spring occupies the middle ground between lighter 300# springs (suited to lighter loads and smoother rides) and stiffer 500–600# options (preferred for heavier vehicles or aggressive off-road use). Matching spring rate to vehicle mass, payload capacity, and intended use prevents premature wear, maintains correct ride height, and preserves shock absorber longevity.