Mark Simpson

Upper Control Arm Replacement

Mark Simpson
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Duration:   22  mins

Front control arms, also known as A-arms, are crucial components of a classic car’s front suspension system. These components have evolved over time, and their design and function have been refined to improve the ride quality, handling, and safety of classic cars.

Early cars, such as those from the late 19th and early 20th centuries, often featured simple leaf spring suspensions and a straight axle. These suspensions provided a basic means of absorbing shocks and vibrations from the road but offered limited control over the wheel’s movement. As automobile design evolved, so did the need for more advanced suspension systems to provide better ride comfort, handling, and stability. Control arms began to replace simple leaf spring suspensions in the 1920s and 1930s.

The primary functions of control arms in classic car front suspensions are as follows:

Wheel Location: Control arms play a critical role in locating and guiding the movement of the wheels. They ensure that the wheels move in a controlled and predictable manner, providing stability and control during acceleration, braking, and cornering.

Suspension Geometry: Control arms help maintain the suspension geometry, which is crucial for maintaining proper tire contact with the road. This, in turn, affects the vehicle’s handling and ride quality.

Damping and Shock Absorption: Many classic cars feature coil spring suspensions that work in conjunction with control arms. The control arms help support and position the coil springs, which absorb and dampen road shocks and vibrations.

Steering Support: In many classic cars, the steering linkage, including the steering knuckle and wheel hub, is connected to the control arms. This allows for precise control of the wheel’s direction and alignment.

Tire Wear and Traction: Properly functioning control arms help ensure even tire wear and maintain consistent tire contact with the road. This, in turn, improves traction and tire longevity.

Handling and Comfort: By providing a means to fine-tune suspension settings and by reducing body roll during cornering, control arms contribute to a classic car’s handling characteristics and ride comfort.

Classic car front suspensions may have different types of control arms, such as upper and lower control arms, depending on the specific design and make of the vehicle. Some classic cars also have adjustable control arms, which allow for further customization of suspension settings to match the driver’s preferences or the car’s intended use.

While the upper and lower control arms themselves seldom wear out, they are susceptible to damage and corrosion. However, the ball joints and bushings are considered “wear items” and require regular maintenance and replacement. Fortunately some classic cars are popular enough where manufacturers have offered complete replacement control arms with new ball joints and bushings for less than the components would cost separately. Our project 1967 Mustang is well supported by the aftermarket, so we opted to replace the entire control arm. Follow along as we remove and replace the upper control arms and give our pony car improved handling, ride quality, and safety.

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