Take your 1964–1966 Mustang’s rear suspension to the next level with QA1’s fully engineered 4-link and 9-inch housing system. This complete kit replaces outdated leaf springs with a modern triangulated 4-link and double adjustable coilovers - giving you full control over ride quality, stance, and handling. Designed for street performance, autocross, or restomod builds, it’s a serious performance upgrade that fits like it belongs there.
BUILT FOR PERFORMANCE & PRECISION
QA1’s 4-link design eliminates axle wrap, wheel hop, and the inconsistencies that plague leaf-spring setups. Geometry-optimized brackets maintain correct pinion angle and suspension alignment through the full range of motion, providing improved traction and predictable handling on any road surface.
DOUBLE ADJUSTABLE COILOVERS
Fine-tune your Mustang’s performance with QA1’s double adjustable shocks, which independently control rebound and compression. Whether you’re dialing in for track conditions or adjusting for a smoother street ride, you get precise control with 18 clicks of adjustment on each circuit.
STRENGTH MEETS STYLE
Each kit includes QA1’s custom fabricated 9-inch housing, engineered for serious horsepower and clean fitment. The housing’s formed brackets, heavy-duty 3” OD ¼” wall axle tubes, and 31-spline alloy axles deliver maximum rigidity and support up to 800 HP. Combined with a semi-gloss powder coat finish, it’s as tough as it looks.
RIDE HEIGHT FLEXIBILITY
Easily adjust ride height from factory stock height to 3” lower, giving you full control over stance without compromising drivability or geometry.
FEATURES & BENEFITS
- Application-specific fit for 1964–1966 Ford Mustangs
- Complete rear suspension system: 9” housing, 4-link, and coilovers
- Double adjustable shocks: independent rebound and compression control
- Adjustable ride height from stock to –3”
- Eliminates wheel hop and axle wrap
- Heavy-duty fabricated 9” housing rated to 800 HP
- 31-spline 1541H alloy axles rated to 650 HP
- Big Ford “New Style Torino” flanges with 2.5” axle offset
- 5x4.5” bolt pattern for wide wheel compatibility
- Includes drain plug, fill plug, vent port, and jack pad for easy service
- ½” x 3” wheel studs for better fitment with aftermarket wheels
- Durable semi-gloss powder coat finish
- Weld-in installation with self-fixturing brackets for perfect alignment
- Made in the USA
EASY INSTALLATION
The QA1 system uses self-fixturing weld-in brackets that ensure correct geometry and alignment without a custom jig. The included 9” housing bolts into place for a clean fit — no guesswork required.
FITMENT NOTES
- Fits 1964–1966 Ford Mustangs
- For use with QA1’s included 9” rear housing
- Requires 31-spline Ford 9” third member (sold separately)
- Factory wheel mounting surface: 57-3/8”
- Big Ford “New Style Torino” flanges (2.5” offset)
- 5x4.5” bolt pattern (standard Ford)
- Weld-in installation required
Specifications
- Vehicle PositionRear
- Shock ValvingDouble Adjustable
- Springs IncludedYes
- Spring Rate130lb/in.
- Axle Shaft Splines31
- Width at wheel mount surfaces57 3/8in
- Brake FlangeBig Ford "New Style Torino"
- Brake Offset2.5"
- Bolt Pattern5x4.5 in
