What is a driveshaft and where is it located?

The driveshaft, sometimes called a prop shaft, is an integral part of the drivetrain. It links the engine to the wheels and can transfer power to them, moving the vehicle forward.  Without a driveshaft, your engine could produce all the power in the world and you’d never go anywhere.

There are two kinds of driveshafts: front and rear.
Front driveshafts used in 4WD vehicles that use both a front and a rear driveshaft. The front driveshaft transfers power from the transfer case to the front axle housing to power the front wheels. 

In front engine vehicles with rear-wheel drive (RWD), all-wheel drive (AWD), and four-wheel drive (4WD), rear driveshafts transfer power from the transmission to the rear differential to power the rear wheels.  Front-wheel drive (FWD) vehicles have constant velocity axles to power the front wheels and don’t use a rear driveshaft.

The front driveshaft found underneath the vehicle's body attaches to the transfer case via a rubber flex plate, known as a giubo. The flex plate is made of flexible rubber and allows for difference in speed between the transfer case output and the driveshaft. That helps keep driveshaft vibrations low.

The rear driveshaft also found underneath the body of the vehicle, in the middle, running front to back. The rear driveshaft is called a prop shaft to differentiate it from the front driveshaft, because the rear driveshaft plays a similar role to the propeller shaft in a boat.

Driveshafts attach to the transmission and differential in a few different ways. Some vehicles use universal joints, known as u-joints or Cardan joints. Universal joints are made up of a cross shaft that has a cup with needle bearings inside of it on all four ends of the shaft, and these cups are clamped or clipped in to a receiver that is called a yoke. Other vehicles use a constant velocity joint, also known as a CV joint. A CV joint uses a series of balls and grooves covered with a rubber boot to allow a range of motion. Other vehicles use a rubber flex disc, referred to as a rag joint, or giubo. The rubber of the flex disc helps keep driveshaft vibrations low.

A longer shaft experiences more torque, often a long driveshaft is composed of two pieces. These are types of drive shafts have a driveshaft support that mounts to the underside of the vehicle.

How do I know if my front or rear driveshaft needs to be replaced?

Driveshaft problems take the form of a strong vibration under the floorboards. These vibrations get worse under acceleration. Another sign of driveshaft problems is rattling or clunking noises. These are especially noticeable during gear changes.

These issues result from a loose or unbalanced driveshaft. The u-joints can wear out over time from exposure to dirt, salt, moisture, and other road hazards. The rubber of the flex plate become stiff or dry rotted, which leads to vibrations. A driveshaft support bearing can become worn and loose, leading to driveshaft vibrations. Since these parts wear together, you want to replace all the associated parts along with your driveshaft.

The easiest way to test for driveshaft problems is to check for driveshaft looseness by hand. If you can move the driveshaft up and down by hand, it's too loose. In a 4WD vehicle, you can drive the vehicle in RWD. If the vibration goes away under these conditions, then the problem is with the front driveshaft.

Can I replace a rear driveshaft myself?

Replacing a rear or front driveshaft is not a highly technical or complicated job, but it is physically demanding. An assistant can definitely help make the job go more smoothly. Before you begin, you’ll need to raise and secure the vehicle. You’ll want to set the emergency brake to keep the driveshaft from spinning while you work. If you’re working on a manual, put the transmission into first to hold the driveshaft in place and chock the wheels to keep the vehicle in place for when the driveshaft is removed. 

The driveshaft needs to be properly aligned to work correctly, so make marks where it attaches so you can line up the new one. Remove the bolts that hold the driveshaft to the axle housing or differential. You may have to spin the driveshaft to reach all the bolts. Your assistant can help by releasing the emergency brake and putting the transmission into neutral. Once you have the bolts out, carefully lower the front or rear of the driveshaft. Then remove the bolts that hold the driveshaft to the flex plate or slide the yoke out of the transmission and carefully lower it. If you are replacing the flex plate or the center support, you can do this while the driveshaft is removed.

Lift your driveshaft into place and have your assistant hold it in place as you insert the first couple of bolts. From this point you should be able to reverse the preceding steps to put everything back together.

Need a rear driveshaft replacement?

While your engine is responsible for generating the power needed for your vehicle’s wheels to turn and move your car or truck, all of that energy would go to waste without the driveshaft. A damaged driveshaft will instantly impact the performance of your vehicle as it is a key component of the vehicle’s drivetrain. If you have a rear driveshaft that is in need of replacing, look no further than 1A Auto. We carry a large selection of aftermarket front and rear driveshafts for many makes and models at great prices.

At 1A Auto, we make shopping for a replacement front or rear driveshaft for your car, truck, SUV or van easy—we're here to help you select the right part for your vehicle!