Driveshafts 101: What You Need To Know


All automobiles have a driveshaft. This is the piece of equipment that transfers the energy created by the energy into the force that drives the wheels. It’s actually a very simple device.

The driveshaft looks like a simple cylinder. What it actually is is an outer tube that protects the shaft itself, which is a spinning cylinder. The frequency of the spin depends on the engine. In addition to automobiles, boats and motorcycles also have driveshafts. Some vehicles may, in fact, have more than one. It is important that the driveshaft balance be maintained.

If your car is rear wheel drive, it will have a long drive shaft that runs the length of the car and then a differential to transfer torque to the wheels, which are connected by short half-shafts. You may sometimes hear a mechanic talk about an automobile’s ‘diff’, shortening the word to something easier to say. A front-wheel drive vehicle has two short shafts, one to each front wheel or, more commonly, a device called a ‘transaxle’, which serves the purpose of the drive shaft, transmission and differential. Obviously, this is reversed in rear-engined vehicles. There are various different arrangements, dependent on the exact configuration. Four wheel drive vehicles have a slightly different configuration again, with front and rear shafts and differentials.

So, what do you need to know about your driveshaft? It’s a moving part and, as such, can fail. Being relatively simple, it is less likely to fail than your transmission (transaxles, of course, are as vulnerable to failure as standard transmission). The most common problem is with the balance of the shaft. An unbalanced driveshaft causes vibration and a loss of power. Race car drivers spend a lot of time worrying about balance because it can make the difference between winning and losing. For the ordinary person, making sure your driveshaft is balanced can help with both power and fuel efficiency. In some cases the universal joints attached to the shaft have to be repaired or replaced.

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