Q: What is the Function of Universal Joints and CV Joint and How to Check for Wear?
A: Universal joints are mechanical couplings that connect two rotating components at different angles. They consist of a yoke on each side connected by a crosspiece called a trunnion, with needle bearings in cups at each end of the trunnion for smooth torque transfer. Wear in the needle roller bearings can cause vibration, noise, and ultimately disintegration of the bearings. To check for wear, the driveshaft can be turned while holding the rear differential pinion flange or front half coupling, and any movement indicates considerable wear. A prybar can also be used to check for looseness between the universal joint and the driveshaft or flange. If wear is present, the driveshaft should be replaced. The constant velocity joint on the forward end of the driveshaft is not serviceable and must be replaced if worn or if the boot is damaged.