Conv Rear Spring 5in x 13in x 400#

The Conv Rear Spring 5in x 13in x 400# from AFCO Racing Products is a purpose-built coil spring engineered for serious vehicle suspension tuning and performance applications. Whether you're building a drag car, circle track machine, or street performance vehicle, this conventional rear spring delivers the progressive damping and load-carrying capability needed to dial in your chassis geometry. Rear springs are critical components in suspension setup—they support vehicle weight, maintain ride height, and work in concert with shocks and anti-roll bars to control body roll and tire loading during acceleration, braking, and cornering.

This AFCO coil spring features a 400 lb/in spring rate with 5-inch outer diameter and 13-inch compressed length, making it ideal for rear-suspension applications where moderate to firm spring rates are required. The 400-pound-per-inch rate is stiff enough to minimize chassis squat and maintain consistent ride height under heavy acceleration, yet responsive enough to track road surface irregularities without harshness. The steel construction with black powder-coat finish resists corrosion and provides durability through countless heat cycles and road salt exposure. At 10.03 lbs per spring, the mass is kept low to reduce unsprung weight—a key factor in suspension responsiveness and tire contact patch consistency. The conventional coil design (as opposed to linear or variable-rate springs) offers predictable, linear load characteristics that simplify setup and tuning.

Mechanics and enthusiasts upgrading independent or solid-axle rear suspensions will find this spring compatible with custom chassis builds, lowered street cars, and competition vehicles where factory spring rates are insufficient. Proper installation requires accurate ride-height measurement and typically involves adjusting perches or spring seats to achieve desired anti-squat and load bias. Always pair rear springs with appropriately valved shocks and verify that total suspension geometry—including wheelbase, track width, and roll center location—is optimized for your vehicle class and driving style. This spring for sale represents an investment in precision handling and consistent performance tuning for builds where suspension compliance matters.