Just about every part of the suspension system could need replacing at some point, from the springs to ball joints, tie rod ends, control arms and bushings. As cars age and the miles add up, they may lean more in turns, shimmy or make noises over bumps, or develop looseness in the steering. Because suspension parts wear gradually, vehicle owners may not recognize warning signs until something breaks, said Steve Cartwright, a manager at the Federal Mogul Technical Education Center in St. Louis. Federal Mogul manufactures MOOG steering and suspension components for the aftermarket automotive repair industry.
Springs, which actually hold or "suspend" the weight of the vehicle, are key components that may wear out. If a car leans to one side, the suspension makes unusual noises or a driver notices excessive tire wear, a worn or broken spring could be the cause, Cartwright said.
One way to tell is to have an automotive technician measure the height of each corner to see if the car is still at the manufacturer's specifications or is closer to the ground. Even if a vehicle still meets the spec, a technician should do a visual inspection underneath to check the springs and other parts.
Springs maintain the suspension's geometry so that every other part operates in a proper range to control wheel movement. A worn spring can put added stress on the control arms, which Cartwright described as "hinges that hold the wheels in position," and if they become bent that can cause handling, ride control and tire-wear problems. A wheel alignment won't cure problems with springs, control arms or other parts, he added.
"Every car has potential for issues," he said. "The right answer is to have a professional do an inspection because every car is different." That goes not just for the suspension design but in what might wear sooner. For example, lower control arm bushings are prone to wear out on front-drive cars. Bushings are rubber or metal parts that help absorb shock.
A small amount of looseness in the suspension or steering that doesn't get fixed can lead to rapid tire wear, cutting tire life by as much as half. In some cases, suspension parts may be on their way to the graveyard without obvious signs in how the vehicle drives, Cartwright said. Ball joints, for example, which act like a hinge or a pivot point to attach the suspension to a wheel, can steadily wear to the point that one day they just break.
MOOG's Problem Solver website, found here, has diagrams and suggestions on diagnosing suspension problems, but Cartwright said it can be difficult for a car owner to know whether the vehicle needs new ball joints or control-arm bushings, so he recommends having the suspension inspected by a pro.
How often should you have your suspension inspected?
It's hard to put a mileage or time number on it, Cartwright said, but suspension problems can show up in less than three years. The potential for problems is higher in areas that have badly maintained roads that put more stress on suspension parts and in the Snow Belt, where rust never sleeps.
It's better to fix small problems sooner so they don't become big ones later, Cartwright said. He added: "It's a lot easier to fix a cavity than have a root canal."