A dual ball joint suspension uses a pair of arms, one in tension, one in compression, to replace a wishbone, in a MacPherson or SLA suspension. The outer end of each arm terminates in a

ball joint In an automobile, ball joints are spherical bearings that connect the control arms to the steering knuckles, and are used on virtually every automobile made. They bionically resemble the ball-and-socket joints found in most tetrapod animals. ...

, hence the name.

General description

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 A double wishbone suspension is an independent suspension design for automobiles using two (occasionally parallel) wishbone-shaped arms to locate the wheel. Each wishbone or arm has two mounting points to the chassis and one joint at the knuckl ...

readily gives an effective virtual ball joint outboard of the spindle, which is very useful for a suspension designer, allowing negative

scrub radius The scrub radius is the distance in front view between the king pin axis and the center of the contact patch of the wheel, where both would theoretically touch the road. It can be positive, negative or zero. The kingpin axis also known as steeri ...

whilst allowing the ball joints to move in and thus out of the way of the brakes. Some manufacturers use a double ball joint arm to replace both wishbones on a

. This provides further opportunity for optimising the geometry.

Examples

It is used on large cars such as the

Lexus LS 460 The Lexus LS (XF40) is the fourth generation of the Lexus LS line of full-size luxury sedans. Lexus debuted the model line at the 2006 North American International Auto Show, with variants including the standard wheelbase LS 460 (USF40) and lon ...

BMW X5 The BMW X5 is a mid-size luxury SUV produced by BMW. The X5 made its debut in 1999 as the E53 model. It was BMW's first SUV. At launch, it featured all-wheel drive and was available with either a manual or automatic gearbox. The second generati ...