What is true about U-joints?

U-joints, or universal joints, are critical components in vehicle driveline systems that allow for the transfer of power from the transmission to the wheels while accommodating angular changes due to suspension movement. When U-joints wear out, they can create play in the driveline, leading to clunking noises during acceleration or deceleration. This is because worn U-joints can no longer maintain a stable connection between driveshaft components, resulting in clunking as the driveline components shift during operation. This noise is often indicative of a need for inspection or replacement to ensure proper vehicle performance.

The other choices misrepresent U-joints. For instance, while U-joints are commonly found in rear-wheel-drive (RWD) and four-wheel-drive (4WD) vehicles, they are not limited to front-wheel-drive (FWD) applications. Additionally, U-joints generally require lubrication to maintain their function and prevent premature wear, which is contrary to the claim made by one option. Lastly, U-joints serve a different purpose and are designed differently compared to constant velocity (CV) joints, which are often found in FWD vehicles and allow for smoother operation at tight angles.