Most owners know their vehicles require routine maintenance, including periodic inspection of their batteries, spark plugs, tires, windshield wipers, filters and fluids. But often the parts drivers can’t see — such as shock absorbers and struts, located under the vehicle — don’t get the attention they deserve.

In addition to causing an uncomfortable ride and poor handling, weak shocks may cause changes in vehicle ride height. This may lead to increased wear on other suspension components – including tires, ball joints, and springs – which could cause premature component failure in extreme cases. These components often are more expensive to replace than the shocks themselves.

ACDelco, an automotive replacement part service, offers the following vehicle maintenance quiz on shock absorbers:

Q: Is there an obvious sign, like a noise or a jolt that shock absorbers make when they wear out and need replacing?

A: Not really. Shocks wear out gradually, so an incremental loss of handling, control or ride performance may not even be noticeable to the vehicle owner. The vehicle’s shocks should be inspected every time the vehicle comes in for any service.

Q: Which of the following are indications that a vehicle’s shocks may need to be replaced?

a) Vehicle continues to bounce after hitting a road bump

b) Vehicle may take longer to stop

c) Vehicle nosedives when braking

d) Vehicle ride is shaky or bumpy

e) Vehicle sways or leans on turns

A: All five are symptoms of worn-out shocks. Because shocks deteriorate slowly, most drivers say that until the new shocks were installed, they didn’t realize what a significant difference shocks made in comfort, control and handling.

Q: Is there any physical evidence that may indicate a vehicle’s shocks need replacing?

A: The two most common physical signs are: 1) cupping of the tires, that is, fairly regular, small patches of rubber dug out around the tire’s circumference, and 2) oil leaking from the shocks. ACDelco encourages drivers to have their vehicle’s suspension system thoroughly inspected every time the vehicle comes in for any service by a service center that has ASE-certified technicians.