The rear universal joint or U-joint allows the drive shaft to flex at the rear of the vehicle. If your 2000 Ford explorer did not have a rear U-joint, the shaft would break every time the body flexed or went around a sharp corner. Over time, the bearings inside the U-joint weaken. When this happens, you will hear a knocking sound because the shaft is flexing too much. If this occurs, you must replace the U-joint before it breaks completely.
Drive the rear of the Explorer onto a set of ramps, chock the front wheels and place the vehicle in neutral.
Remove the four drive shaft bolts that connect the drive shaft to the rear end with a 12 mm socket and ratchet. Slide the drive shaft forward, toward the transmission, to separate it from the rear end. Slide the shaft backward, toward the rear of the car, to pull the drive shaft spline out of the transmission. You can move the drive shaft to a workbench.
Pry the retaining clips from the U-joint using a pair of pliers and a flat-head screwdriver. There are four U-joint clamps in total.
Place a socket onto the U-joint cap that measures slightly smaller than the cap. Drive the cap out of the other side of the shaft U-joint by striking the socket with a 5-lb. sledgehammer. Complete this step with all four caps.
Remove the U-joint from the drive shaft and place the new one into it.
Place the caps back onto each end of the U-joint and pound them into place with the sledgehammer.
Place the retaining clips over each cap and snap them into place using your pliers.
Place the drive shaft spline into the transmission, place the other end against the rear end and secure the shaft with the four bolts, using a socket and ratchet.
