The drive shaft is responsible for converting the torque from the engine into energy that can be used to drive the vehicle. The design of this mechanism varies depending on whether a vehicle uses rear-, front- or all-wheel drive. For front-engine vehicles with rear-wheel drive, the power has to be sent to the back wheels, which requires a longer drive shaft that runs from the engine to the rear axle. The wheels are connected to the drive shaft system with universal joints, or u-joints, that provide flexibility without taking up much room so there is space for the suspension system.
Front-wheel drive vehicles typically have two separate drive shafts, one for each front wheel, and constant-velocity (CV) joints are used in place of u-joints. They tend to be more flexible than u-joints and require less-frequent maintenance. The drive shafts for all-wheel drive vehicles can vary between makes and models, but they are generally based off of either the rear or front-wheel drive designs. Heavy duty vehicles, such as SUVs, are more likely to have drive shafts that are based on the extended rear-wheel drive setup.
Drive shaft failure is not a common problem, but things can go wrong. The most common issues will tend to occur with the joints - lack of lubrication and worn or loose joints. Loose joints will probably only need to be tightened and lubricating dry joints can prevent further wear and tear. When the joints wear out, they will need to be replaced. The center bearing on a rear-wheel drive system can also cause problems, and will need to be replaced if it is defective.
When there is a problem with the drive shaft, motorists may notice a number of symptoms. Loose joints and worn center bearings can cause the car to shudder when accelerating from a stop or low speeds. A loud clunking noise when the engine shifts gears, a constant knocking sound or squeaking and vibrations could indicate that the joints are worn. It may also mean that the joints need to be lubricated or joint clamps need to be tightened.
Another symptom of a drive shaft problem is difficulty when making sharp turns. If you notice that the tires are offering a lot of resistance when trying to U-turn or maneuver the vehicle in a small space, there may be issues with the drive shaft.