Your car's entire suspension system is very important for protecting everything under the hood of the car, as the suspension system absorbs the impact of bumps and dips in the road. In turn, there is less wear and tear on connectors, hoses, and all other parts of the car's systems. While your car's manufacturer may have provided recommendations as to when the suspension and shocks in particular should be checked for needed repairs, there are some other signs to look out for that often mean the springs, struts, and other pieces of the suspension need repair or replacement.
Longer stopping distance
If you notice that your car needs more time to stop or tends to slide when you hit the brakes, this can be a problem with the brakes themselves, such as a worn pad or rotor. However, the shock absorbers also help to stop the car when you hit the brakes, as they absorb some of the weight and movement of the car and help the wheels to become rigid and immobile. Worn shocks will then result in a longer stopping distance or more time needed for the car to stop. You may also notice rocking or dipping of the car when you hit the brakes, called a nosedive, which also signals that the shocks are worn and need replacing.
As with stopping time, vibrations from the steering wheel and the car itself when you're driving can be a problem with the brakes or the alignment of the wheels. However, remember that the car's shocks work to absorb vibration and movement when you're driving over any road, not just when you hit a bump. When they're worn out, those shock absorbers are rocking up and down and causing vibration rather than absorbing the movement of the car's wheels, so you feel that vibration in the steering wheel and cab of the car.
Uneven tire wear
Uneven tire wear can also be caused by a number of issues, but if the shocks are not absorbing the impact of bumps in the road as you drive, this can cause tires to drag or skid as certain areas hit the pavement. Because tires rotate so quickly, you may not notice this dragging, but may notice unevenly worn patches on the tires. If you've checked the alignment and balancing of the tires and have ruled out improper tire inflation or size, have the shocks checked when you notice this uneven wear pattern.