Your car's suspension system is responsible for smoothing out the ride and keeping the car in control. Specifically, the suspension system maximizes the friction between the tires and the road to provide steering stability and good handling. The suspension system also provides comfort for passengers to limiting the impact of particular road conditions to not only the car, but the passengers riding inside.
The suspension system is made up of several components, including the chassis, which holds the cab of the car. The springs support the vehicle weight and absorb and reduce excess energy from road shocks, along with the shock absorbers and struts. Finally, the anti-sway bar shifts the movement of the wheels and stabilizes the car.
On vehicles with SLA suspensions, there are four ball joints that, if loose, can cause noises such as clunks, squeaks, or groans when passing over bumps or dips in the road. On vehicles with strut suspensions, there are no ball joints unless the suspension is a wishbone combination, but the upper mounting plate can become worn out, and cause noises.
Don’t Overlook Ride Height
Ride height affects tire wear, steering, and handling. If the chassis is sagging, then weak springs are likely the cause. Measuring the ride height and checking it against the specifications for the vehicle can determine whether new springs are needed or not. When replacing springs, they should be replaced in pairs to make the ride height uniform. Weak springs are more likely to fail. Modern springs are coated with plastic to protect from corrosion, but if the plastic cracks or breaks, the springs can become corroded and potentially break. Bushings are made of rubber or urethane and usually fail with age. Old bushings can cause noise, and greasing them will quiet them, but they should be replaced.
The Overlooked Upper Bearing Plate
If an upper bearing plate is damaged, the strut may need to be replaced. If the plate is rusted, loose, worn, noisy, binding or damaged, it has to be replaced. Symptoms of a bad bearing plate include:
- Steering noise such as snapping, popping, creaking or groaning sounds when turning
- Suspension noise such as clunking, rattling or popping on rough roads
- Increased steering effort (most noticeable with manual steering) brought on by binding in the bearing plate