BMW 335i Coil Spring

What is a coil spring on a car?

Generally speaking, the suspension system of a vehicle is the combination of three parts: springs, shock absorbers, and linkages. These parts together connect the body of the vehicle with wheels, while allowing them to move relative to a certain degree.

Nowadays, there are two mainstream options for springs in the suspension system: leaf springs and coil springs. The details of leaf springs and the comparison between leaf springs and coil springs will be introduced in our blogs. The leading role in this article is the coil spring.

The coil spring in a vehicle looks similar to all the other springs we have seen in our life, but the coil spring for cars is manufactured to deal with a more challenging environment. A coil spring can help the vehicle to absorb and release the energy from the vertical movement of the wheels, and also provides a small amount of flexibility in the transverse direction. Through this, coil springs can filter out some unpleasant vibrations and increase the contact time between the wheels and the ground, providing a comfortable driving experience and improving the performance of the vehicles.

Since coil springs play such an important role in the suspension system, it is crucial to make sure they are in good condition. Without a well-functioned coil spring, driving can become uncomfortable and even dangerous. There isn’t a concrete rule that says how long a coil spring can last. Even though they don’t usually break, they can still wear down over time, especially if the vehicle is often driven in a hazardous environment or bad roads. It is better to check your coil springs regularly to make sure they can support your car the way they should.

Bad coil spring symptoms

• Decrease in ride height: Coil springs are supposed to support your vehicle. If you notice your vehicle sagging, especially when the car is loaded, it is likely that there is something wrong with the coil spring.
• Unusual tire wear: When the support from coil springs weakens, the balance of the vehicle can be impacted and the weight distribution on tires will be affected as well. As a result, some tires can wear down faster than others. What’s more, the angle of the wheel can change and this will make the uneven tire wear worse.
• Noise: One of the coil springs’ jobs is to filter out the noise under the suspension system. If you find the vibration and noise increase unusually when you are driving, this could be a sign of a malfunctioned coil spring.
• Vehicle bounce: One obvious sign of bad a coil spring is unexpected bounces when your vehicle driving through speed bumps. When you drive your vehicle over a speed bump, the coil spring is supposed to prevent your car from jumping, at least at a slow speed. But with a faulty coil speed, conditions like speed bumps can cause uncomfortable bounces.
• Jounce bumpers damage: If you see the jounce bumpers under your vehicle damaged, or if there is an impact mark on the suspension stop made by a jounce bumper, it could be a strong signal saying that you might need to check your coil spring.