"The Watts link suspension works to improve the ride and handling of the Mustang by minimizing the rear-axle lateral movement, optimizing the roll center, and adding four directional bushings to the Watt's link. The pivot point is mounted to the axle and works with rigid frame mounts to optimize the rear roll center, providing a balanced feel and maximum lateral grip. The Watt's link utilizes state-of-the art directional bushings, which differ in stiffness depending on the direction of the load being applied. These bushings are positioned to offer extra stiffness for lateral loads and less stiffness for vertical loads. This causes quicker weight transfer in corners, which allows for a quicker turn-in and offers a more comfortable ride. Working in conjunction with the sway bar, the Saleen Watt's link keeps the tires as flat as possible, creating better control, and has been proven to improve speed by 2 percent. Lap times on average were two to three times faster."
Coil Springs
Springs are necessary to separate the chassis from the vehicle and allow the tires, wheels, and suspension to absorb imperfections in the road surface. Without springs, your vehicle would ride like a skateboard or shopping cart. You'd get a bouncy ride and the tires would have great trouble staying in contact with the road, thus causing a loss of control.
For many, changing the ride height of their Mustang is mostly done for aesthetic reasons, as most people prefer to close the wheelwell-to-tire gap. Once again, the factory has to meet myriad requirements that some of us are willing to let go of for the sake of appearance or performance. Lowering a car means using shorter-than-stock springs. This in turn requires a stiffer spring, and while that can help the body resist roll during cornering, too stiff a spring can cause the tires to skip and slide in the turns.
With aftermarket coil springs being such a popular modification, we went to Eibach Springs and asked a few questions regarding coil springs. Eibach's research and development manager, Phong Diep, handled our inquiry, and this is what he had to say:
Q: What are the three most important things to know when shopping for coil springs?
A: "The ride height the spring will set the vehicle at, the spring rate, and the quality of the spring."
Q: What's the difference between specific rate and progressive rate springs?
A: "Specific rate or progressive rate is usually determined by whether the vehicle has progressive or linear suspension geometry.Due to the linear geometry of the Mustang's suspension geometry, progressive spring rates are used."
Q: Can you give examples of linear or progressive suspension setups?
A: "In linear suspension geometry, the change in wheel movement and spring displacement remains unchanged throughout suspension travel. In a progressive suspension geometry or increasing wheel rate suspension, the change in spring displacement increases with wheel movement. This would make a linear rate spring seem progressive."
Q: Can you go too low?
A: "Yes. Ideally, you want the vehicle as low as possible to lower its center of gravity, however, as low as possible will leave nothing for suspension movement. There must be enough travel remaining for the suspension to absorb bumps."
Q: What effect, if any, does vehicle weight have on ride quality and spring-rate choices?
A: "You can determine the spring rates necessary to achieve the ride quality you want for any vehicle weight. Furthermore, each spring must have enough rate to keep the vehicle from bottoming out and provide the correct handling for the vehicle. Heavier vehicles will require more rate, however, there must be enough damping. The damper is another important element in the ride quality of a vehicle."