QA1 RCK52373 Rear Pro-Coil Double Adjustable Coilover Conversion Kit 12in 200lb Springs

The QA1 RCK52373 is a bolt-in rear coilover conversion kit engineered for 1973–1977 GM A-Body vehicles. This complete Pro-Coil System replaces the factory rear suspension with a performance-tuned coilover setup — no cutting or welding required. The kit is fully American-made and 100% dyno tested, delivering a significant upgrade in handling, ride quality, and stance adjustability over the stock configuration.

Double Adjustable Proma Star Shocks: The included double adjustable aluminum shocks offer 18 positions of independent compression adjustment and 18 positions of independent rebound adjustment, yielding 324 possible valving combinations. This level of tunability allows precise suspension calibration for any driving condition, from daily street use to performance track days.

High-Travel Pro Coil Springs: The American-made lightweight springs are purpose-built for QA1's Pro Coil system. Their reduced coil count and smaller wire diameter create greater distance between coils, resulting in increased suspension travel, reduced unsprung weight, and faster reaction time for optimized handling performance. This kit includes 200 lb/in spring rate springs (12-inch length), suited for vehicles with heavier builds or firmer ride preferences.

Key Features:

• Bolt-in installation — no cutting or welding required
• 2 double adjustable Proma Star aluminum shocks
• 18 compression + 18 rebound positions = 324 valving combinations
• 2 high-travel Pro Coil springs — 12 in. length, 200 lb/in rate
• Fully threaded shock body for precise ride height adjustment
• Specially designed USA-made mounting brackets and all necessary hardware included
• 100% dyno tested and serialized
• Rebuildable and revalveable by QA1 factory or authorized service centers
• Lowers vehicle ride height
• Made in the U.S.A. — ISO 9001 certified quality system

What's Included:

• 2 double adjustable Proma Star shocks
• 2 high-travel coil springs (12 in. / 200 lb/in)
• All mounting brackets and necessary hardware

Warranty: QA1 Double Adjustable shocks are eligible for a Limited Lifetime Warranty upon registration at QA1.net/Warranty. All other kit components are covered by a one-year warranty against defects in materials and workmanship from the original date of sale.

Note: Lower shock mount bracket may not be compatible with aftermarket rear end housings. Spring rate selection may vary depending on vehicle weight, intended use, and personal preference.