Dual ball joint suspension
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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, hence the name.
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[edit] General description
The two arms, the spindle, and the body, form a four bar link. Careful optimisation of the geometry leads to an effective virtual ball joint outboard of the spindle, which is very useful for a suspension designer, allowing negative Scrub radius whilst keeping the ball joints fairly close in to the body, out of the way of the brakes.
[edit] Examples
It is used on large cars such as the BMW X5, Ford Territory and GM's Zeta chassis.
[edit] Disadvantages
The extra ball joint adds weight and cost. It also increases steering friction, and the parasitic friction in the suspension. The geometry has some undesirable characteristics that need careful management, such as returnability from full lock when parking.
[edit] Reference
"The Automotive Chassis Engineering Principles"
AUTHOR(S): J. Reimpell H. Stoll J. W. Betzler
