U-joints are a small, simple component - in fact, they have changed much since the very first automobiles. However, on any vehicle with a driveshaft, its ability to move depends entirely on the u-joint being there. You’ll often hear “maybe it’s the u-joints” as a solution offered for problems with a vehicle - but what are they, what do they do, and how do you know if yours is bad? R & M Automotive in Rockvale, TN has the answers.