GMC 26064028 Pinion Seal

Raise the rear of the vehicle and support it securely on jackstands. Block the front wheels to keep the vehicle from rolling off the stands. Disconnect the driveshaft and fasten it out of the way. On semi-floating axles, use an inch-pound torque wrench to check the torque required to rotate the pinion. Record it for use later. Scribe or punch alignment marks on the pinion shaft, nut and flange. Mark the relative positions of the pinion, nut and flange before removing the nut. Count the number of threads visible between the end of the nut and the end of the pinion shaft and record it for use later. Keep the companion flange from moving while the self-locking pinion nut is loosened. Remove the pinion nut. Withdraw the companion flange. It may be necessary to use a two or three-jaw puller engaged behind the flange to draw it out. Do Not attempt to pry behind the flange or hammer on the end of the pinion shaft. Pry out the old seal and discard it. Lubricate the lips of the new seal with high temperature grease and tap it evenly into position with a seal installation tool or a large socket. Make sure it enters the housing squarely and is tapped into its full depth. Align the mating marks made before disassembly and install the companion flange. If necessary, tighten the pinion nut to draw the flange into place. Do not try to hammer the flange into position. Apply non-hardening sealant to the ends of the splines visible in the center of the flange so oil will be sealed in. Install the washer and pin ion nut. Tighten the nut carefully until the original number of threads are exposed. On semi-floating axles, measure the torque required to rotate the pinion and tighten the nut in small increments until it matches the figure recorded. In order to compensate for the drag of the new oil seal, the nut should be tightened more until the rotational torque of the pinion slightly exceeds what was recorded earlier, but not by more than 5 in-lbs. Connect the driveshaft and lower the vehicle.