As the engine in your 2003 Dodge Ram develops torque, the transmission and differential transmit the torque to the rear wheels. The pinion gear in the rear differential of your 2003 Dodge Ram is attached to the driveshaft by the pinion yoke. Over time the pinion seal, which keeps the gear oil in the differential from leaking past the pinion yoke, will become brittle and lose its sealing ability. Replacing the pinion seal will prevent loss of gear oil and damage to the differential.
Step 1 Apply the parking brake. Place wheel chocks behind the front wheels. Raise and support the rear wheels by lifting the differential, using a floor jack, and sliding jack stands under the rear axles. Lower the Dodge onto the stands.
Step 2 Remove the driveshaft using a 12 mm wrench to loosen and remove the four retaining bolts that attach the driveshaft to the pinion yoke. Place a drain pan under the transmission tail shaft. Pull the driveshaft out of the transmission tail shaft, being careful not to drop the caps located on the rear U-joint.
Step 3 Remove large nut, in the center of the pinion yoke, that attaches the yoke to the pinion gear shaft. Slide the yoke off the pinion shaft.
Step 4 Remove the old pinion seal by prying it out of the differential housing, using a large screwdriver. Position the new seal into the housing and tap it gently into place using a hammer.
Step 5 Reinstall the yoke onto the pinion shaft and tighten the retaining nut to 210 ft-lbs. using a torque wrench. Avoid over-torquing the nut and damaging the pinion bearing. Reinstall the driveshaft and tighten the bolts to 14 ft-lbs.
Step 6 Top off the fluid level in the differential by adding fluid through the hole, sealed with a rubber plug, in the differential cover until it begins to drip out of the hole.
Lower the truck from the jack stands and test-drive. Check for leaks after the test drive.
Items you will need: Wheel chocks, Floor jack, Jack stands, Socket set, Wrench set, Screwdriver set, Drain pan, Hammer, Torque wrench
