QA1 RCK52371 Rear Pro-Coil Double Adjustable Coilover Conversion Kit 12in 150lb/in

The QA1 RCK52371 is a bolt-in rear coilover conversion kit engineered for 1973–1977 GM A-Body vehicles. Designed for enthusiasts who demand both street manners and track-ready performance, this complete kit replaces the factory rear suspension with a fully adjustable coilover system — no cutting or welding required.

At the heart of this kit are two double-adjustable Proma Star aluminum shocks, each offering 18 independent positions of compression adjustment and 18 independent positions of rebound adjustment, yielding 324 possible damping combinations for precise suspension tuning. The fully threaded shock body allows ride height adjustment to dial in the perfect stance or fine-tune corner weight balance.

The included American-made High Travel Springs are purpose-designed for QA1's Pro Coil systems. Their reduced coil count and smaller wire diameter create greater spacing between coils, increasing travel and reducing unsprung weight for faster suspension response and improved cornering stability. This kit ships with a spring rate of 150 lb/in.

What's Included:

• 2 double-adjustable Proma Star aluminum shocks
• 2 high travel coil springs (150 lb/in rate, 12 in. length)
• USA-made mounting brackets
• All necessary hardware for installation

Key Features:

• Bolt-in installation — no cutting or welding
• Double-adjustable damping: 18 compression × 18 rebound positions (324 total combinations)
• Fully threaded aluminum shock body for ride height adjustment
• Ride height range: up to ½" higher than stock, down to 2.25" lower than stock
• High Travel Springs reduce unsprung weight and optimize suspension response
• 100% dyno tested and serialized at the factory
• Rebuildable and revalveable by QA1 or QA1 Authorized Service Centers
• Eligible for QA1 Limited Lifetime Warranty (registration required at QA1.net/Warranty)
• Proudly made in the USA in Lakeville, Minnesota

This kit is compatible with QA1's adjustable front coilover systems, enabling a complete front-to-rear suspension transformation for the ultimate in ride and handling balance.