QA1 R357-170N Four-Link Kit with Narrowed 9in. Rear Housing MOD Series 170 lb/in Spring Rate

The QA1 R357-170N is a complete four-link rear suspension kit paired with a custom QA1 Narrowed 9" rear housing, designed specifically for 1970–1981 GM F-Body vehicles. This all-in-one kit eliminates the factory leaf spring setup and replaces it with a triangulated 4-link system and MOD Series coilovers, delivering ride height adjustability, improved ride quality, and instant center adjustability for street and performance driving.

The narrowed 9" housing is engineered specifically to work with mini-tub applications, providing 2-1/2" of additional narrowing per side for maximum wheel and tire clearance. Every component in this kit is manufactured and tested by QA1 to ensure a proper fit, minimizing installation time and eliminating the guesswork of sourcing mismatched components.

9" Rear Housing Specifications:

• Fabricated center section engineered for maximum strength and durability
• Formed trailing arm brackets reduce flex under high loads
• Heavy-duty 3" OD, 1/4" wall axle tubes built for high-performance applications
• 31-spline 1541H alloy axles rated to support up to 650 HP; housing rated up to 800 HP
• 56-1/8" narrowed wheel mounting surface width
• Narrowed 2-1/2" per side for use with mini tubs
• Big Ford "New Style Torino Flanges" with 2.5" axle offset for broad brake compatibility
• 5x4-3/4" factory bolt pattern for a wide range of wheel options
• 1/2" x 3" wheel studs for better fitment with alloy wheels
• Durable semi-gloss powder coat finish for long-lasting protection
• Drain plug, fill plug, vent port, and jack pad included for easy maintenance
• Includes T-bolts and housing studs for axle shaft assembly and third-member installation
• High-quality roller bearings for smooth operation and long-lasting reliability

MOD Series Coilover & 4-Link Features:

• Spring rate: 170 lb/in
• QA1 MOD Series shocks with four-way adjustable valving for precise tuning
• Remote nitrogen canisters for consistent damping performance
• Triangulated 4-link design provides ride height, ride quality, and instant center adjustability
• Accommodates up to 12-inch-wide wheels and 335 tires
• Includes spanner wrench
• Shock absorbers backed by a limited lifetime warranty (registration required at QA1.net)

Installation Notes:

• Bolt-in design with minimal welding required
• QA1 Subframe Connectors strongly recommended
• May require exhaust modification; not compatible with over-the-axle exhaust
• Verify wheel and tire fitment prior to installation
• Center section (differential) not included

Proudly made in the USA at QA1's facility in Lakeville, Minnesota, the R357-170N is the definitive rear suspension upgrade for serious 2nd Gen F-Body builds.