Control arms, and their integrated ball joints, are some of the most crucial components on a BMW suspension. The control arms literally control the wheel and suspension as they go through their range of motions. They do more than just keep the alignment in a constant spec - they are a vital locating component for the suspension itself. A faulty or worn control arm or ball joint is a very dangerous and potentially life-threatening problem so make sure they are inspected and replaced at regular intervals.
Most control arms for BMWs consist of an inner and outer ball joint made of plastic, rubber, Delrin, or metal and covered in grease with a rubber boot to seal it from the outside. The ball joint rotates and spins as the control arm goes through its movements and that will wear the ball joint and make it loose. The grease inside the housing can also get used up, evaporate, or become contaminated from moisture and foreign particles. As the ball joint becomes worn it can result in excess movement within the housing. Your steering and handling will become less precise and there is usually a light clunking or clicking sound. In rare and extreme cases the ball joint can separate from the control arm completely, leading to a total loss of suspension and steering control. You should have the ball joint play checked annually and replace them every 3-4 years. Most track organizations will not allow a car if they are older than three years.
Control arms also take abuse from impacts and handling forces. Aluminum control arms will generally bend and prevent an accurate alignment. Steel control arms will crack and fracture and require close inspection annually and replacement every 3-4 years.
We sell OE BMW, OEM, and performance upgrade control arms from proven manufacturers. The control arm is so important to a BMW suspension that we insist on only top quality brands and designs and will never sell a control arm based on price alone. We also have upgrade packages with superior designs and better bushing options and we have bundled these together with valuable package savings.
