QA1 DD501-12250 HD Pro Rear Weld-In Coilover Conversion Kit, Double Adjustable, 3.0" Axle, 250lb/in Spring

The QA1 DD501-12250 is an HD Pro Rear Weld-In Coilover Conversion System designed for vehicles with a 3.00" axle tube. Engineered for both street and race applications, this complete kit provides everything needed to convert a solid-axle rear suspension to a fully adjustable coilover setup — without costly custom fabrication.

At the heart of this system are two QA1 Proma Star double-adjustable coilover shocks, which offer independent rebound and compression tuning across 18 positions each. This allows precise on-car damping adjustments to suit anything from daily street driving to the drag strip or road course. All shocks are 100% dyno tested and serialized for quality assurance.

Ride height is highly configurable: the axle-mounted brackets provide adjustment in ¾" increments, and the coilover shock itself allows additional fine-tuning — delivering a combined 9" of total ride height adjustability. The kit is built for vehicles with a rear axle weight of 1,700–2,600 lbs., and the double shear bracketry ensures strength and durability under demanding loads.

What's Included:

• (2) QA1 Proma Star DD501 double-adjustable coilover shocks
• (2) 12" linear rate springs — 250 lb/in. rate
• Weld-in upper shock mount tube: 1-5/8" O.D. x .095" wall x 40" long
• Axle mount bracketry and all necessary mounting hardware

Key Features:

• Double-adjustable Proma Star shocks — 18-position independent compression and rebound adjustment
• Double shear bracketry for heavy-duty strength and support
• 9" total ride height adjustability
• Designed for 3.00" diameter axle tubes
• Welding required for installation — spanner wrench P/N T114W or T115W required (sold separately)
• 100% dyno tested and serialized
• Made in the USA — Lakeville, Minnesota
• Eligible for QA1 Limited Lifetime Warranty (registration at QA1.net/warranty required)

The QA1 DD501-12250 rear coilover conversion kit is a proven solution for hot rods, restomods, street performance builds, and drag racing applications seeking maximum suspension tunability and a custom stance.