The drive shafts in your Jeep depend on regular maintenance and greasing of the U-joints for long-term dependability. The universal joints contain needle bearings that, without proper lubrication, will heat up and seize. Jeep uses a type of grease called EP, or Extreme Pressure, when the U-joints and drive shaft are assembled in the factory; so it is best to continue using EP grease to lube your U-joints. EP grease is available through Jeep dealers or at most automotive parts stores.
Raise the rear of your Jeep off the ground with a jack, then position a set of jack stands under the frame rail. Lower the jack until the Jeep is resting securely on the jack stands. Place the transfer case of the Jeep in neutral. Be sure to block the front wheels so the Jeep cannot roll.
Crawl under the Jeep and locate the zerk fittings on the U-joints on the drive shaft. The zerk fittings are small steel fittings that screw into the U-joint. They look like a small metal nipple and will often have a little grease on them. You may have to turn the drive shaft so you can access them.
Place the hose from your grease gun on the zerk fitting, pushing it on until is snaps onto the zerk. Pump the handle of the grease gun, forcing grease into the joint, until you see grease start to seep out around the base of the U-joint caps. Pull the hose off the zerk, giving it a sharp tug to remove it.
Move to the next U-joint and repeat the process until all U-joints in the rear shaft have new grease. Position the jack under the Jeep and raise it off the jack stands. Remove the stands, then lower the Jeep to the ground. Move your jack to the front of the Jeep and raise it off the ground. Place the jack stands under the front frame rails, then lower the Jeep onto them.
Locate the zerk fittings in the U-joints that are located in the front drive shaft. Grease them by snapping the hose onto the zerk then pump the handle of the grease gun until grease seeps out around the U-joint caps. Remove the hose from the zerk and grease the second U-joint on the front drive shaft.
Raise the Jeep off the jack stands with the jack and remove the stands from under the Jeep. Lower the Jeep to the ground and engage the transfer case again. Remove the jack from under the Jeep.
