The purpose of a car’s control arm

by | Suspension

The system of shock absorbers, springs, and links that connects the car’s chassis to its wheels is known as a vehicle’s suspension. Its job is to regulate the vehicle’s ride quality, handling, and overall dynamics when it’s in motion and to bear its weight.

But what exactly is a car’s control arm? One of the essential parts of a car’s suspension system, the control arms connect the front wheels to the car’s chassis. The control arms let the driver direct the vehicle’s movement in any direction and keep the vehicle’s wheels aligned with the ground. Despite their apparent simplicity, control arms play a crucial part in any vehicle’s safety and ease of operation.

How Does A Control Arm Work?

Each of the front wheels of a vehicle with a suspension designed for use on public roads has a control arm attached to the front axle. The essential components are cast iron, cast aluminium, or stamped steel. Strong, sturdy, and damage-resistant control arms made of steel and iron is a must. Control arms made of cast aluminium are used in lightweight configurations.

The suspension geometry of a particular vehicle dictates whether the control arms are A-shaped, L-shaped, or wishbone-shaped. These parts connect the steering knuckle of a wheel to the chassis of a vehicle.

Using bolts and bushings, the control arm attaches to a hinge at the vehicle’s frame or body. These bushings prevent the arm from rubbing against the wheel hub as it moves up and down. The bushings soften and smooth out the ride, and they help lower NVH levels.

The control arm is connected to the steering knuckle by a ball joint, allowing for unhindered rotation in all directions of the wheel. The steering knuckle may swivel, and the wheels can move while the car is moving thanks to the ball joint.

Many automobiles feature upper and lower control arms that link to the lowest and highest steering knuckle locations for each front wheel. These structural considerations allow for a more robust assembly, guaranteeing better handling and steadiness.

An upper and lower control arm configuration is the most common. However there are variations. On vehicles with a MacPherson setup, the top control arm is replaced with a strut. Rear control arms are not a common feature of vehicles with independent rear suspensions.

What’s The Function Of a Control Arm

The function of a control arm is simple. Stabilizing the vehicle by ensuring that the chassis and the wheels move in harmony while in motion, it links the steering knuckle to the frame. At the end of the day, control arms aid in achieving harmony between the car’s steering and suspension systems systems, which in turn reduces road noise and allows the driver to better manage the vehicle.

The ball joint on the control arm acts as the pivot point of the steering system, enabling the car to be rotated in either way while it is being driven forward or backward. The control arms’ frame-side hinge joint maintains wheel contact with the road surface, whether on smooth asphalt or rough terrain. The control arm is a two-part assembly that allows the vehicle to make the turns and maneuvers required for safe and effective operation on roadways.

Damage to Control Arms

Although the control arm is built to withstand significant stress and impact, it is nevertheless subject to the same wear and tear as any other part of the vehicle and has a finite lifetime. Most of this deterioration is linked to how the car is driven during its lifetime. The control arm function of vehicles that are often driven harshly or on unpaved conditions may deteriorate more quickly, which might have a detrimental effect on handling, comfort, & safety.

Deterioration of the frame, the bushing, or the ball joint are the three most common causes of a broken control arm. Rust, excessive bending, and broken parts following a collision or impact are all potential causes of frame damage. Wear and tear is the most common cause of bushing failure over time. Ball joints are prone to damage from wear and strain or even shattering because of the constant rubbing between the moving components.

A poorly functioning control arm or one that has been broken can display a variety of symptoms. These symptoms include vibration in the vehicle, a roaming steering wheel, imbalance, unsteady wheels, strange grinding sounds, variations in stopping, and uneven tread wear on the tires. If any of these problems manifest themselves, it may be time to consider replacing the control arms. A mechanic can make that call for you.


While they may not be the most exciting or intricate parts of a car, control arms are essential to the vehicle’s smooth functioning. They were developed to respond to the driver’s steering inputs and the surface variations encountered on the road. Due of this feature, they are essential to the comfort, control, and maneuverability of a vehicle.