• The front suspension of a car is held together by a ball joint, which acts in a similar fashion to the ball joints found in the human body (such as the shoulder or the knee). The ball joint links the steering knuckles of the suspension to the control arms, allowing the wheel and suspension to sway and move as the car is moving and turning. The ball joints can cause several significant issues with a car if they are damaged.
  
  

Tire Wear

• A common symptom of worn ball joints is uneven tire wear. This occurs when the suspension and wheels are misaligned, leading to the tires not meeting the road properly. Instead of being centered with the weight of the tires in the middle of the tire, the tires wear on the edges or possibly the center of the tire. This is clearly visible because the tread of the tires will be worn down at a greater rate at certain points of the tire than others. In some cases, the tires will be worn to the point that the threads will stick out.
  
  The most common pattern of tire wear associated with a defective ball joint is camber wear. This is tire wear that is specific to one side of the tire because of the suspension being uneven.
  
  

Steering

• One of the most dangerous conditions that could occur from worn ball joints is problems with steering. If a ball joint is worn or damaged, it will not allow the steering mechanism to fluidly turn the wheels in response to the driver. This can make steering difficult and make driving the car dangerous--especially if the driver needs to take sudden, evasive action.
  
  A worn ball joint can make the steering feel either too loose or too tight depending on how the ball joint and socket are wearing. If the ball joint and socket are wearing out together, the ball joint will become smaller while the size of gap in the socket will increase. This will increase the tolerance in the joint and make steering feel loose or sloppy. However, a worn ball joint can also cause tight steering, making it hard to turn the car quickly and feel like the car is losing power steering.
  
  

Loud Noises

• A ball joint will make loud noises as it begins to wear. These noises can start as minor clicks that are felt in the steering wheel, but gradually increase to loud thumps and clunks as the damage to the ball joint gets worse. The noise can be especially noticeable when the weight of the car shifts to and from the wheel with the bad ball joint--such as when the car drives over a pothole.