Mustang II Coil Spring - 2.5/3.5 x 8 500#

The Mustang II Coil Spring – 2.5/3.5 x 8 500# by QA1 is a purpose-built suspension component engineered for vehicles running a Mustang II-style independent front suspension geometry. Whether you're building a hot rod, restomod, or adapting a modern chassis to classic car proportions, this coil spring provides the progressive rate support needed for controlled ride height and load distribution. QA1 is an industry standard for high-performance suspension, trusted by fabricators and enthusiasts who demand repeatability and durability in their builds.

This spring features a 500-pound rate per inch of compression, matched with 2.5-inch inner and 3.5-inch outer coil diameters and an 8-inch free length, making it suitable for mid-travel suspension architectures where controlled spring force is critical. The progressive-rate design absorbs small road irregularities while maintaining stiffness under dynamic cornering loads and braking events. QA1's manufacturing precision ensures consistent spring constants across production batches, eliminating the guesswork in suspension tuning and allowing you to dial in geometry and dampening without fighting inconsistent spring behavior.

Mechanics and fabricators working on Mustang II spindle conversions, kit car platforms, or custom chassis builds will find this spring ideal for front-end applications where weight distribution demands a moderate spring rate. Installation pairs best with quality dampers matched to the 500# rate and proper ride-height measurement to ensure geometry targets are met. At 4.89 lbs per unit, account for spring weight in your overall suspension mass calculations, and verify clearance with your chosen control arms and bump stops before final assembly.