Taking the strain
STEERING & SUSPENSION
Few components are exposed to harsher conditions than those fitted to the suspension, leading Rob Marshall to give an overview about how and why some parts wear faster than others
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Perhaps the simplest and most common joint, used in suspension and steering systems, is the humble ball and socket, known otherwise as a Ball Joint. It comprises a circular ball that rotates within a lubricated socket housing, enclosed and protected by a tightly secured boot, or dust cover. MOOG reports that natural wear symptoms result from the ball pin becoming loose in its housing, resulting in a knocking noise. This is down to high axial and radial supported loads from typical use (from accelerating to cornering), causing natural wear of the socket that, being plastic, tends to wear faster than the ball. First Line explains that other suspension parts share the same ball pin/housing design and, consequently, technicians will see many different variations. MOOG adds that, in use, lower ball joints face the highest forces. This is why they are always oversized, compared to track-rod ends, or antiroll bar/drop links, for example, to make their lifespan similar to that of other ball joints within the suspension system. ZF Aftermarket (under its Lemförder and TRW brands) reminds us that even ball joints should be replaced in axle sets.
The fight that some suspension components put up against the technician is a testament to the harsh conditions that they must endure, when fitted
