Driving with failing or broken struts is dangerous because they do not sufficiently dampen side-to-side and front-to-back weight transfers. Such swaying prevents the tires from properly gripping the road, which makes turning corners and braking difficult. Accordingly, properly functioning struts are a critical safety feature.
A strut is a self-contained suspension assembly that attaches a wheel to the vehicle's frame and includes a shock absorber mounted in a coil spring. However, unlike a simple shock absorber that only controls the speed of weight transfer in the car, a strut carries the weight of the vehicle and provides structural support for the suspension system. Thus, failing struts cause accelerated wear to the car's tires, ball joints, springs, steering linkages and constant-velocity joints.
The signs of worn struts often involve a change in the car's handling. During braking, the front end may begin to dive, and upon accelerating, the back end may squat. The vehicle may increasingly roll or sway on turns and bounce or slide sideways on rough, winding roads. Additionally, it may start to noisily "bottom out" on bumps. To avoid the unsafe driving conditions associated with advanced wear, a car's struts should be checked by a technician at every oil change.