The two arms, the spindle, and the body, form a four-bar link. Use of the linkage at the lower suspension connection of either a MacPherson strut or a short long arms suspension readily gives an effective virtual ball joint outboard of the spindle, which is very useful for a suspension designer, allowing negative scrub radius whilst allowing the ball joints to move in and thus out of the way of the brakes.
A four-bar link is established by the two arms, the spindle, and the body. The use of this linkage at the lower suspension connection of either a MacPherson strut or a short long arms suspension enables the creation of an effective virtual ball joint located outside the spindle, which is very useful for a suspension designer, as it facilitates negative scrub radius while allowing the ball joints to move in and out of the way of the brakes.