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Used-Car Suspension Inspection for Peace of Mind

That new-to-you car, crossover or minivan has a shiny body suspended on top of four wheels by a sophisticated array of springs, bushings, rods, and struts.

These components are specified, calibrated, and linked to one another to create the unique ride and handling principles intended by engineers for the ride in question. Like any other part of a used vehicle, they will eventually wear down and require attention and replacement.

In order to ensure your used-ride candidate's suspension is in good working order, a mechanical inspection of its various components is in order. A mechanic can assess the condition of your used ride's suspension system in a matter of minutes and determine if the seller is trying to pass an expensive repair off to you.

Remember: A properly functioning suspension will turn in better ride quality along with optimal tire life, safety, and handling in all situations. A suspension in need of repair can be noisy, uncomfortable, and even dangerous.

Here are some checks drivers can make on a test drive before visiting a mechanic for a full inspection.

Photo: Matt St-Pierre

Shock Absorbers
Many shock absorbers are filled with a fluid that can leak out if the part is failing or has failed. Get down low and look into the vehicle's wheel-wells for the shock absorber, which is likely located above and behind each wheel. Any obvious signs of an oily fluid leaking down the shock absorber assembly should be addressed.

Strut Mounts
Depending on the type and age of the vehicle in question, a check of its strut mounts is in order. This component lets the front struts "rotate" in relation to the body of the car, allowing the wheels to steer. When strut mounts wear out, the bearings inside of them typically fail which makes it harder to steer the vehicle and puts additional strain on the steering system.

From the driver's seat (while parked) turn the wheel fully from lock to lock, noting any binding sensation through the wheel along the way. This may be accompanied by a clicking or popping noise. If you notice any unwelcome sounds, have someone steer the wheel while you stand in front of the car with the hood popped. If the sound comes from the top of the "shock tower" area, tell your mechanic you suspect the strut mounts are worn out.

Check the Alignment
Inspect all four tires for signs of uneven wear across their treads. If one or more tire is worn more heavily at the inside or outside of its treads, the vehicle's alignment is off, which could be evidence of a suspension-related issue. Vehicles with out-of-whack alignment can wear their tires out more quickly and burn excessive fuel. Ask your mechanic to have a closer look.

Especially on used trucks and sports cars, there's a fairly high likelihood that the suspension system has been modified. Ask the owner if they've lowered the suspension on that sports model or lifted the suspension on that truck or SUV. If they have, you'll want to make sure that the quality of the parts, and their installation, is top-notch. Suspension modifications can add a degree of visual flare and fun factor to the ride you're considering, though they can also create suspension-related problems, and may even be illegal. Be sure to have a mechanic approve any suspension system modifications on the model you're considering or opt for a model with original suspension if you have any concerns.

Numerous rubber or polyurethane bushings are used to isolate suspension components from each other without metal-on-metal contact. As bushings age, they can crack, dry up and fall out which results in noisy contact between suspension components. Any unwelcome sounds from the vehicle's suspension could be caused by worn-out bushings.

Ride Quality
One fantastic way to determine the condition of a used ride's suspension system is to simply note is ride quality. A car with a healthy suspension will absorb bumps without much fuss, and fairly quietly, while rebounding once and settling back to its normal ride height. A vehicle that makes noise, feels unstable or bounces excessively after going over a bump likely has some suspension repairs in its near future.

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