QA1 DS501-175V1 Pro Rear Weld-In Coilover Kit Single Adjustable 175/350 lb/in Spring 3.25in Axle

The QA1 DS501-175V1 Pro-Rear Weld-In Coilover Conversion Kit is a complete single-adjustable coilover system designed to upgrade the rear suspension of muscle cars, classic trucks, street rods, and performance vehicles. Purpose-built for 3.25-inch axle tubes, this kit delivers a significant handling and ride quality improvement over factory leaf spring setups with a straightforward weld-in installation.

At the heart of the system are two single-adjustable Proma Star DS501 shocks featuring simultaneous compression and rebound (DS) valving adjustment. The evenly spaced valving increments eliminate harsh transitions between clicks, giving the driver smooth, predictable tuning from a comfortable street cruise to a firm performance setting.

Key Features:

• Two single-adjustable Proma Star DS501 coilover shocks with simultaneous compression and rebound adjustment
• Two 12-inch variable-rate springs rated at 175/350 lb/in for progressive, responsive handling
• Designed for vehicles with 3.25-inch rear axle tubes
• Axle-mounted brackets offer 3/4-inch ride height adjustment increments
• Up to 9 inches of total ride height adjustability for full stance control
• Lightweight aluminum shock construction for reduced unsprung weight
• Weld-in upper shock mount tubing included (1-5/8" O.D. x .095 wall x 40" long)
• Includes axle mount bracketry, upper shock mounts, tubing, and all necessary hardware
• Ideal for drag racing, street performance, and street rod applications
• Made in the USA — manufactured in Lakeville, Minnesota
• QA1 lifetime warranty available upon registration at QA1.net/warranty

Installation requires welding. A QA1 spanner wrench (T114W or T115W) is recommended for final spring perch adjustment. This kit is a proven, cost-effective solution to replace leaf springs with a fully adjustable coilover system without the need for extensive custom fabrication.