Installing Steeda’s Aluminum Rear Control Arms on a 1991 Mustang (As seen in Mustang360.com by Michael Johnson)
The rear control arms on 1979-2004 Mustangs have a big job. Not only do the control arms transfer the axle torque to the chassis, the angled upper arms also locate the rear axle during cornering. Over their lifespan, the rear control arms and their soft rubber bushings get a workout. In the case of our 1991 GT test subject, decades of clutch dumps, burnouts, and hard corners had the control arms begging for mercy. Even on the street, launches were squishy and clunky. The upper control arms’ rubber bushings were damaged so badly that the arms rubbed on the bushing shells.
When looking for replacement arms, we chose Steeda’s Aluminum Rear Control Arms for 1979-2004 Mustangs. Their Lower Control Arms are fabricated from 6061-T6 aluminum and available with two different bushing options: 4500 series for street, road racing, and light drag use, and 4600 series for drag racers and high-horsepower, heavy street cars. We chose the former for our mostly stock 1991 Fox-body.
The Steeda Aluminum Upper Control Arms are also made from the same heat-treated, 6061-T6 aluminum. Both sets of arms include Steeda’s thoughtful three-part bushings that use hard center bushings sandwiched by softer outer bushings. The harder center bushing transfers the torque loads to the chassis more directly while the soft outer bushings allow flexibility for suspension movement.
A key feature of the aluminum construction is weight reduction: the lower control arms weigh 35% less and the upper arms weigh 40% less than the stock stamped steel arms. Pretty impressive.
The upper arms also included new polyurethane bushings for the differential end. This was welcome, as we found one of our stock upper control arm bushings was broken and started to slide out from its shell. The following photos detail the installation process and highlight why the Steeda Aluminum Rear Control Arms are a welcome upgrade on this weary 1991 Mustang GT.