What is a U Joint on a Nissan Sentra?

The Nissan Sentra is a Front Wheel Drive(FWD), and as such has no u-joint. Since the engine is transversely(sideways) mounted, there is no driveshaft to connect from the transmission to the axe housing. Instead directly fromt he transmission outdrive there are a pair of halfshafts which go out to the wheels. Each halfshaft has an inner and outter CV joint. CV Means Constant Velocity. They are smoother in operation, and can be turned into a deeper arc then can a u-joint usually. As for why CV joints are not used in place of u-joints everywhere t's a matter of economics. u-joints are MUCH stronger, and cheaper to manufacture, but they will not work in a FWD situation. Rear Wheel Drives drivelines are subjected to ALOT higher torque multiplication then any front wheel drive is capable of. While it's possible to get extreme amounts of horsepower out of those little engines, it's the torque that really breaks things, not the horsepower.