1. Preparation and Safety:
* Safety First: This job involves heavy components and potentially sharp tools. Wear safety glasses, gloves, and appropriate clothing. Use jack stands – *never* work under a vehicle supported only by a jack.
* Gather Tools: You'll need a wide array of tools, including:
* Axle stands
* Torque wrench (capable of high torque settings)
* Gear installation tool (specific to your rear end type)
* Bearing race installer/remover
* Socket set (metric and possibly SAE)
* Wrenches (various sizes)
* Hammer (soft-faced and possibly a ball-peen)
* Pry bars
* Drain pan
* Gear lube
* Shims
* Dial indicator (for setting pinion depth)
* Magnetic drain plug
* Consult a Repair Manual: A factory service manual for your specific 1989 Dodge half-ton truck is absolutely essential. It will provide detailed diagrams, torque specifications, and procedures specific to your rear end type (e.g., 8.25-inch, 9.25-inch, etc.). This is crucial to avoid damage.
* Identify your rear end: Determine the exact type and ratio of your current rear end before ordering replacement gears.
2. Removal of the Rear Axle:
* Secure the vehicle: Chock the front wheels and use jack stands to safely lift the rear of the truck.
* Drain the differential fluid: Allow it to drain completely into your drain pan.
* Disconnect components: Disconnect the driveshaft(s), brake lines, and any other components connected to the axle housing.
* Remove the axle: Carefully lower the axle assembly.
3. Disassembly of the Differential:
* Remove the axle shafts: This often involves using a slide hammer and appropriate pullers.
* Remove the ring gear: This may require specialized tools depending on your specific rear end.
* Remove the pinion gear and bearings: This is a critical step requiring precision and often specialized tools.
* Inspect parts: Carefully inspect all components for wear, damage, or any signs of breakage.
4. Gear Installation:
* Install new bearings: Use proper bearing installation tools to avoid damaging the bearings or the housing.
* Install pinion gear and set pinion depth: This is a crucial step requiring precise measurement using a dial indicator to ensure proper mesh with the ring gear. Incorrect pinion depth will lead to gear failure.
* Install ring gear: Carefully install the new ring gear, ensuring proper alignment and mesh with the pinion gear.
* Install shims: Use shims to adjust the pinion depth and the ring gear backlash to factory specifications.
* Reassemble the differential: Carefully reassemble all components, ensuring everything is properly seated and torqued to the specifications listed in your repair manual.
5. Reinstallation and Testing:
* Reinstall the axle: Carefully reinstall the axle assembly, making sure everything is connected properly.
* Refill with gear lube: Use the correct type and amount of gear lubricant specified in your repair manual.
* Test drive: Test drive the vehicle carefully, paying close attention to any unusual noises or vibrations.
This is a highly simplified overview. The actual process is significantly more complex and requires specialized knowledge, precision, and the correct tools. Incorrect installation can lead to serious damage to the rear end, potentially resulting in expensive repairs or accidents. Seek professional help unless you have extensive experience working on differentials. A mistake could lead to catastrophic failure and potentially injury.
