Effect of Force Vectoring Spring implementation into a Twistbeam Rear Suspension

A twistbeam is a very cost effective rear suspension architecture which has drawbacks compared to an independent rear suspension. One drawback is the lateral compliance during cornering compromising the handling of the vehicle. Common solutions to correct this issue are complex reinforcements or an additional Watts linkage. However, these solutions drive high cost and additional weight. The challenge was to find a solution which reduces the gap to the functional performance of a multilink rear suspension. Due to the bush attachment, the set-up of a twistbeam is always a compromise between ride comfort and vehicle dynamics. The more comfort is desired the softer the bushings will be, resulting in less agility and slower vehicle response. The target was to determine a way to separate ride comfort and dynamic agility. A solution was found using a special set of springs working as a dynamic anti-compliance mechanism. The so-called force vectoring springs are designed in a way, that they create a lateral force component by their coil shape inclination. At the Ford K&C rig a significant reduction of toe compliance was shown and subjective drive evaluations confirmed the vehicle dynamics improvement.