QA1 DS501-12100V Pro-Drag Rear Weld-In Coilover Kit Single Adjustable 100/200 lb/in Spring 3.00in Axle

The QA1 DS501-12100V is a Pro-Drag rear weld-in coilover conversion kit designed for vehicles in the 1050–1300 lb. rear axle weight range. Featuring single-adjustable Proma Star shocks paired with 100/200 lb/in variable rate springs, this kit is purpose-built for drag racing, street performance, and street rod applications.

QA1's single-adjustable Proma Star shocks deliver simultaneous compression and rebound damping control with a single dial. Each adjustment increment is evenly spaced throughout the range, eliminating harsh transitions between clicks for smooth, predictable tuning. The lightweight aluminum shock bodies keep unsprung weight low while maintaining the durability needed for performance use.

Ride height is fully adjustable through a combination of axle-mounted bracket positioning (¾" increments) and the coilover shock's own adjustment range, providing a total of 9" of ride height adjustability. Installation is a straightforward weld-in process—no excess fabrication required.

Kit Includes:

• 2 single-adjustable Proma Star coilover shocks
• 2 variable rate springs (100/200 lb/in)
• Axle mount bracketry for 3.00" axle tubes
• Upper shock mount tubing (1-5/8" diameter x .095 wall, 40" long)
• All mounting and spring hardware

Key Features:

• Single-adjustable simultaneous compression and rebound damping (DS valving)
• Variable rate 100/200 lb/in springs for progressive suspension response
• Designed for 3.00" diameter axle tubes
• Up to 9" total ride height adjustability
• Lightweight aluminum shock construction
• 100% dyno tested and serialized
• Revalveable and rebuildable at QA1 factory or authorized service centers
• Made in the USA — manufactured in Lakeville, Minnesota
• Lifetime warranty (registration required at QA1.net/warranty)

Installation Notes: Welding is required. Requires QA1 spanner wrench T114W or T115W for spring collar adjustment. Designed for 3.00" axle tubes.