REMOVAL & INSTALLATION
- Raise and safely support the rear of the truck safely using jackstands.
- Remove both rear wheels and drums.
- Matchmark the driveshaft and pinion flange, then disconnect the rear U-joint and support the driveshaft out of the way. If the U-joint bearings are not retained by a retainer strap, use a piece of tape to hold bearing caps on their journals.
- The pinion rides against a tapered roller bearing. Check the pre-load by reading how much torque is required to turn the pinion. Use an inch pound torque wrench on the pinion flange nut and record the reading. This will give combined pinion bearing, carrier bearing, axle bearing and seal pre-load.
- Remove pinion flange nut and washer. A suitable pinion holding tool should be used keep the flange from turning when loosening the nut.
- With a suitable container in place to hold any fluid that may drain from the rear axle, remove the pinion flange.
- Apply GM seal lubricant No. 1050169 or equivalent, to the outside diameter of the new pinion flange, then install the pinion flange.
DO NOT hammer on the pinion flange in order to install it to the stem.
- Install the washer and a new pinion flange nut finger tight.
- While holding the pinion flange, tighten the nut a little at a time and turn the drive pinion several revolutions after each tightening to set the rollers. Check the pre-load of bearings each time with an inch pound torque wrench until the same pre-load is achieved as the reading that was obtained in Step 4. For vehicles through 1991, tighten the nut an additional 3-5 inch lbs. (0.3-0.6 Nm) past this point.
- Remove the support then align and secure the driveshaft assembly to the pinion flange. The original matchmarks MUST be aligned to assure proper shaft balance and prevent vibration.
If fluid was lost from the differential housing during this procedure, be sure to check and add additional fluid, as necessary. For details, please refer toChapter 1of this manual.
- Install the rear drums and wheels.
- Remove the jackstands and carefully lower the vehicle.