Most cars today have shocks in the rear and spring/strut assemblies in the front. Both struts and shocks work very similarly, and the biggest difference between the two setups is the presence of suspension springs on the front (note that some cars do have springs in the rear).
Suspension springs are made from coiled steel, and are usually painted to protect them from rust and deterioration. They’re very strong (they have to be to help support the weight of the car’s front end and engine while driving). Your suspension springs work all the time. They’re under more stress while you’re driving, but they must also bear weight while the car is parked.
Over time, suspension springs will begin to sag a bit, and they can lose some of their “springiness”. However, outright failure is very rare, and most drivers will find that their springs last for the life of the vehicle. With that being said, they can be damaged, particularly in an accident, or if another suspension component fails, causing a cascading effect that damages the spring. They can also be damaged by rust and corrosion if the paint is worn off, exposing the underlying metal to the elements.
While failure is very rare and chances are good that you will never need to replace your suspension springs, knowing a few signs of potential failure can be very helpful. If a spring was to fail, your suspension could be damaged (the strut would receive significantly more stress than it was designed to handle).
- Car leans to one side
- Coil spring is visibly broken
- Rust or deterioration visible on the spring
- Ride quality is rougher than usual (can also indicate a failed shock/strut)
If you suspect that one of your car’s suspension springs has failed or is about to fail, a certified mechanic can help to inspect the entire suspension, and replace a failed suspension spring if needed.