J&M 79-04 Mustang Double Adjustable Street Race Upper Control Arms (Black)

Street Race On Car Adjustable Upper Control Arm Mustang 79-04. Just like the lower control arm bushings in the Mustang the upper control arm can have a significant impact on the vehicle’s ride, comfort, handling, acceleration, noise and vibration. When the car leans (i.e., rolls) in a turn, one side of the chassis moves upward relative to the rear axle, the other side moves downward, and the upper control arm must twist (rotate) to allow for the axle to articulate through its suspension travel. This rotation causes the control arm bushing to bind. If this bind becomes excessive, it will raise the rear wheel rate and produce sudden, uncontrolled, undesirable changes in handling (e.g., snap oversteer).

Ford minimizes this suspension bind by using compliant rubber bushings in the upper control arm. This very “soft” bushings help accommodate the necessary motion of the control arms during body roll. However, the rubber bushing does not provide much in the way of forward and aft support, which can cause wheel hop during hard acceleration and braking.

It has become common practice to replace the stock rubber control arm bushings with solid or two piece polyurethane bushings to resolve the shortcomings of the soft rubber bushings. Hard polyurethane bushings eliminate wheel hop, reduce axle deflection, and improves straight line grip. However, the downside of common aftermarket bushings such as delrin, steel, stiffer rubber, solid or two piece polyurethane bushings is they prevent the necessary movement of the control arm during body roll, which in turn produces significant binding in the suspension when the vehicle is cornering. The polyurethane bushings also place unnecessary high stresses on the upper torque box mount, which is the attachment point for the control arm to the chassis. Standard aftermarket control arms do not allow for rotation of the control arm during cornering because of the stiffness of the bushings.

Street Race On Car Adjustable Upper Control Arm Mustang 79-04. J&M Products designed and built a Double Adjustable tubular upper control arm which will eliminate the unwanted uncontrolled control arm flex. Round tubing is harder to work with but has many other advantages over square or rectangular tubing. It is stronger in bending, torsion, and also lighter than square or rectangular tubing.

J&M Products then solved the shortcomings of the factory rubber and other aftermarket polyurethane and stiffer rubber bushings. J&M Products accomplished this with their Patent Pending 3 piece synthetic elastomer bushing combination. By spending countless hours looking and dissecting the geometry and the need of the rear suspension they have come out with bind-free bushings set up. J&M Products incorporates a very hard inner synthetic polymer ball which is surrounded by soft socket outer cups. This combination allows the bushing to articulate like a spherical bearing during cornering but the hard inner ball does not allow the bushing to deflect during acceleration giving you great traction during acceleration like solid bushings but remains completely bind free during cornering for great predictable traction in the corners.