You can test most suspension components at home with nothing more than your hands, a tape measure, and a floor jack. The simplest check, the bounce test, takes about 30 seconds per corner and reliably catches worn shocks and struts. But a thorough inspection goes further, covering ride height, tire wear, noises, and individual parts like ball joints and wheel bearings. Here’s how to work through each test.
The Bounce Test
Park on a flat, level surface with the engine off and the transmission in park. Walk to one corner of the vehicle and press down firmly on the body above the wheel several times to compress the suspension. Then let go and watch how the car responds.
A healthy shock or strut will let the car rise back to its resting position and settle within one or two oscillations. If the corner bounces more than two or three times before stopping, the damper on that side is worn. Repeat this at all four corners. It’s common for the fronts to wear faster than the rears, especially on front-wheel-drive cars, so don’t skip any corner just because one feels fine.
Measure Your Ride Height
Sagging springs are easy to miss because the change happens gradually over months or years. Measuring ride height catches what your eye might not. Start with the vehicle completely unloaded (no cargo, no passengers) and the fuel tank between half and three-quarters full so the weight is representative of normal driving conditions.
Roll the car forward and backward a few feet to let the suspension settle, then park on a flat surface. Using a tape measure, measure from the center of each wheel hub straight up to the center of the fender opening. Record all four measurements. The left and right sides should be very close to equal. A difference of more than half an inch between the same axle’s two sides usually points to a weak or broken spring on the lower side. You can also compare your numbers to the factory specification in your owner’s manual or service guide if one is available.
Measuring hub-to-fender rather than ground-to-fender eliminates the variable of uneven tire wear or mismatched tire sizes, giving you a more reliable reading.
Read Your Tire Wear
Your tires record suspension problems over time, so a close look at the tread can tell you a lot. The pattern to watch for is called cupping or scalloping: localized dished-out spots around the tire where the rubber wears unevenly from one tread block to the next. It looks like someone scooped small divots out of the tread surface in a repeating pattern.
Cupping is strongly associated with worn shocks, struts, or other suspension components. When a damper can no longer control the wheel’s motion, the tire bounces lightly against the road surface instead of maintaining consistent contact. Over thousands of miles, this creates those characteristic scalloped patches. If you spot cupping, plan on inspecting the dampers and bushings on that corner before simply replacing the tire, or the new tire will develop the same pattern.
Standard uneven wear across the inside or outside edge of the tread points more toward alignment problems than suspension failure, though the two often go hand in hand.
Listen for Suspension Noises
Different sounds point to different parts. Paying attention to when a noise happens and what it sounds like narrows the search considerably.
- Clunking over bumps: Usually a strut, shock mount, or loose mounting hardware. A single, sharp clunk as you hit a pothole or speed bump is the classic sign of a worn strut mount or a damper that has lost its internal valving.
- Squeaking or creaking during turns or over uneven pavement: Stabilizer bar bushings are the most common culprit. These rubber bushings dry out and harden over time, and when they do, they squeak as the bar rotates inside them. The noise often gets worse in cold weather.
- Low groaning when the suspension compresses: This typically comes from the damper assembly itself, often indicating internal wear or low fluid.
A quick way to provoke these sounds on purpose is to push down on each corner of the car (just like the bounce test) while a helper listens near the wheel well. You can also drive slowly over speed bumps with the windows down to isolate which corner is making noise.
Check Ball Joints With a Pry Bar
Ball joints connect the steering knuckle to the control arm and allow the wheel to pivot and move up and down. When they wear, you get loose, vague steering and clunking over bumps. Testing them requires the vehicle to be off the ground.
Lift the corner you want to inspect using a floor jack and secure the car on jack stands before getting underneath. With the wheel hanging freely, slide a pry bar between the lower control arm and the steering knuckle, then lever upward. You’re checking for vertical play: any noticeable clunking or movement between the ball joint stud and its housing means the joint is worn. Next, grab the tire at the 3 and 9 o’clock positions and try to push and pull it in and out to check for horizontal looseness in the joint.
If you have a dial indicator, you can attach it to the knuckle near the ball joint and use the pry bar to measure exact axial and radial play in thousandths of an inch. Most ball joints have a maximum allowable play specified by the manufacturer, typically printed on the joint itself or listed in a service manual. But for a basic pass/fail check, the pry bar method works well. Any obvious clunk or visible movement means replacement is due.
Test Wheel Bearings and Tie Rod Ends
With the vehicle still lifted on jack stands, you can check wheel bearings and tie rod ends using the tire as a lever. Grab the tire at the 12 and 6 o’clock positions (top and bottom) and try to rock it. Excessive play in this direction, where the top of the tire tilts away from the car and the bottom tilts in, points to a worn wheel bearing. You can also spin the wheel by hand and listen for a grinding or humming sound, which is another hallmark of bearing failure.
To isolate tie rod ends, grab the tire at 9 and 3 o’clock (left and right) instead. Looseness in this direction, especially if you can see the tie rod end’s boot moving, indicates a worn tie rod end. This distinction matters because both problems can cause a vague, wandering feeling in the steering, but they’re entirely different parts with different repair procedures.
Visual Inspection Under the Car
While you’re underneath with the vehicle on jack stands, a flashlight and your eyes can catch several problems that no other test reveals. Look at each shock or strut body for oil streaks or wet spots. A light film of oil on the outside of a shock is normal, but active dripping or a visibly wet, shiny housing means the seal has failed and the damper is losing its fluid.
Check every rubber bushing you can see on the control arms, sway bar links, and strut mounts. Healthy bushings are smooth and pliable. Cracked, torn, or rock-hard bushings allow metal-to-metal contact and introduce play into the suspension. Also look at the coil springs for cracks or breaks, particularly at the top and bottom coils where stress concentrates. A broken coil spring sometimes snaps cleanly enough that the pieces stay in place, making it invisible from above but obvious from below.
Lifting the Car Safely
Every test that requires getting under the vehicle demands jack stands. A floor jack alone is not safe to work under, regardless of how sturdy it feels. Hydraulic seals can fail, and jacks can slip without warning.
Use at least two jack stands rated for your vehicle’s weight. Lift the car with a floor jack at the manufacturer’s recommended lift point (usually marked on the pinch weld or subframe), then place jack stands at the designated support points before lowering the car’s weight onto them. Once the car is resting on the stands, push against it firmly to test stability before you get underneath. If it shifts at all, reposition the stands and try again.
When Parts Typically Wear Out
Shocks and struts generally last between 50,000 and 100,000 miles, depending on driving conditions. Rough roads, heavy loads, and frequent towing shorten that window. Ball joints and tie rod ends don’t follow a strict mileage schedule but tend to show wear around the same interval, especially on vehicles driven on unpaved roads or in areas with harsh winters where road salt accelerates corrosion.
Rather than waiting for a specific mileage number, running through the tests above during routine maintenance (tire rotations, brake inspections) gives you an ongoing picture of your suspension’s health. Catching a worn bushing or leaking shock early prevents the cascading damage that happens when one failed part forces its neighbors to absorb extra stress.