The axle shaft seal and bearing, which allow the axle to rotate smoothly, sit at the end of the axle shaft on the end of the axle. Over time, the seal and bearings will deteriorate, eventually allowing a leak. However, you can easily replace the seal and bearing with the help of a machine shop. Luckily, most novice mechanics can remove the axle shaft assembly on a 1999 Jeep Grand Cherokee in under a hour.
Lift the rear of the vehicle with a hydraulic vehicle jack. Place jack stands under the frame rails on each side of the vehicle to secure it while changing the axle seal.
Remove the rear wheel lug nuts with a socket wrench and pull the tire and rim off the lug nut studs.
Remove the brake caliper mounting bolts with a socket wrench. Hang the brake caliper with a thick piece of wire. Never allow the brake caliper to be supported by the brake hose.
Pull the brake disc from the hub and slide it off the axle shaft.
Unplug the ABS speed sensor from the wheel hub.
Unscrew the bolts and nuts attaching the axle retaining plate to the axle housing. Some of the retaining nuts can only be accessed through the holes on the flange on the axle.
Attach a slide hammer and axle hub removal attachment to the end of the axle, according to the manufacturer's directions. Use the slide hammer and attachment to pull the axle from the axle housing.
Take the axle shaft assembly to a professional machine shop, unless you have access to a hydraulic press. Have the old seal and bearings pressed out and new seals and bearings pressed into the assembly. If you have access to a hydraulic press, you can replace the bearings yourself, pressing the bearings out and new bearing in with the press.
Lubricate the entire wheel bearing in wheel bearing grease, including the outside surface of the bearing.
Slide the axle shaft assembly into the axle housing. Rotate the shaft in small increments to engage the splines on the end of the shaft with the splines on the side of the differential.
Install the bolts and nuts attaching the axle retaining plate to the axle housing. Using a torque wrench, tighten them to 45 foot-pounds.
Plug the ABS speed sensor into the wheel hub.
Slide the brake disc onto the shaft and rest it against the wheel hub.
Remove the brake caliper from the piece of wire supporting it. Place it over the brake disc and install the brake caliper mounting bolts with a torque wrench. Tighten each bolt to 77 foot-pounds.
Slide the wheel over the lug nut studs. Install the lug nuts with a torque wrench, tightening each lug nut to 105 foot-pounds.
Remove the jack stands from under the vehicle and lower it with the hydraulic vehicle jack.
