What Are Universal Joints?

Understanding U-Joints

Part of the driveline system, universal joints are critical to the ride and handling of your vehicle. An X-shaped part with a bearing at each end, u-joints serve as a connecting point to allow the driveshaft to have lateral and up-and-down movement. Without the universal joint, it would be hard for the vehicle to have any wheel travel to handle bumps, potholes or other road hazards.

Where Are U-Joints Located?

U-joints are found on the vehicle’s driveshaft, typically connecting the driveshaft to the transmission and differential. Additionally, some vehicles have u-joints that connect the front driveshaft to the front differential and transfer case.

What Does a U-Joint Do?

When going over bumps and uneven terrain, the differential moves independently from the vehicle, meaning the differential and transmission aren’t always in alignment. U-joints help the vehicle compensate for the uneven surfaces that are part of daily driving by enabling the driveshaft to move up and down with the suspension. In addition, U-joints help allow a continuous flow of power to the vehicle’s wheels while ensuring that the driveshaft keeps rotating freely.

What Are the Features of a Universal Joint?

What Type of Vehicles Have Universal Joints?

Universal joints can be found on four-wheel drive (4WD), rear-wheel drive (RWD) and all-wheel drive (AWD) vehicles. They are also on other types of vehicles that have a driveshaft like commercial buses and semi-trailer trucks.

How Many U-Joints Are on a Vehicle?

Rear-wheel drive vehicles have two u-joints; one connects the driveshaft to the transmission on one end and the other connects to the differential on the other end. On four-wheel drive and all-wheel drive vehicles, there is the same driveshaft that is on a rear-wheel drive and there is an additional front driveshaft that has u-joints connecting it to the front differential and transfer case. Longer vehicles, like commercial buses and semi-trucks, may have multiple driveshafts that can each have two u-joints.

What About Front-Wheel Drive Vehicles?

Front-wheel drive (FWD) cars and SUVs have all the drivetrain components in the front of the vehicle and don’t have a long driveshaft like 4WD and RWD vehicles. Instead of universal joints, front-wheel drive vehicles have constant velocity joints. CV joints perform a similar function as universal joints – they connect the transmission to the wheels.

Do Universal Joints Need to Be Replaced?

Subject to normal wear and tear, U-joints may need to be replaced during the life of the vehicle. How you use your vehicle and the conditions you drive in can affect the lifespan of universal joints. Learn the signs of a bad U-joint.

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