Here's a general outline. Consult a repair manual specific to your 1991 F-150 4x4 for detailed instructions, torque specifications, and diagrams. This is crucial; the steps and specifics can vary slightly based on the exact axle configuration.
Tools You'll Likely Need:
* Jack and jack stands: Essential for safely lifting the truck.
* Wheel chocks: To prevent the truck from rolling.
* Lug wrench: To remove the wheel.
* Impact wrench (highly recommended): Makes the job significantly easier, especially for removing the hub nuts. A breaker bar and substantial leverage might be necessary if you don't have one.
* Sockets and wrenches: A variety of sizes, including those for the axle nut, caliper bolts, and various other fasteners.
* Penetrating oil (like PB Blaster): To help loosen rusted bolts.
* Wheel bearing press or suitable alternative: This is vital for pressing the old bearing out and the new one in. Improper installation can damage the new bearing.
* C-clamp or similar: May be needed depending on your bearing press solution.
* Torque wrench: Crucial for tightening everything to the correct specifications.
* Pry bar: Might be helpful for separating parts.
* Grease: Pack the new bearing with fresh grease.
* New wheel bearing and race (often sold as a kit): Make sure you get the correct part number for your specific truck. Getting the wrong one will ruin the whole job.
* Safety glasses and gloves: Protect yourself from injury.
General Steps (Consult your repair manual for specifics!):
1. Safety First: Secure the truck safely on jack stands with wheel chocks. Engage the parking brake.
2. Remove the Wheel and Tire: Remove the lug nuts and take off the wheel.
3. Remove the Caliper and Rotor (if necessary): Depending on your specific setup, you may need to remove the caliper assembly (often requires disconnecting the brake line) and the brake rotor to access the hub. Support the caliper with a bungee cord or wire to prevent it from hanging by the brake line.
4. Disconnect the ABS sensor (if applicable): If your truck has ABS, carefully disconnect the ABS sensor from the hub assembly.
5. Remove the Hub Assembly: This often involves removing a large nut (axle nut) on the end of the axle shaft. This will likely require an impact wrench. Once the nut is off, the hub assembly should come off. Again, consult your manual for your specific method. Some hubs require removal of cotter pins and other fasteners.
6. Press Out the Old Bearing: Use a wheel bearing press to carefully remove the old wheel bearing and race from the hub assembly.
7. Press In the New Bearing: Use the wheel bearing press to carefully install the new bearing and race into the hub assembly. Ensure proper seating and alignment.
8. Reassembly: Reassemble everything in the reverse order of disassembly, paying close attention to torque specifications for all bolts and nuts (especially the axle nut!). Make sure the ABS sensor (if applicable) is properly reconnected.
9. Pack the Bearing with Grease: Pack the new bearing with fresh, high-quality wheel bearing grease.
10. Torque Specifications: Use your torque wrench to tighten everything to the manufacturer's specified torque values. This is critical to prevent premature failure and damage.
11. Test Drive: After reassembly, carefully test drive your truck to ensure everything is functioning correctly. Listen carefully for any unusual noises or vibrations from the wheel.
Important Considerations:
* Automatic Locking Hubs: The presence of automatic locking hubs adds a layer of complexity. You'll need to be careful during disassembly and reassembly of the hub assembly to avoid damaging these components.
* Rust and Corrosion: On a vehicle this age, rust and corrosion are likely. Penetrating oil is your friend.
* Repair Manual: A repair manual is absolutely essential for this job. Generic instructions are insufficient.
This is a complex repair that could easily lead to injury or damage if done incorrectly. If you are not comfortable performing this repair yourself, take your vehicle to a qualified mechanic. The cost of a professional repair might be worth the peace of mind and assurance of a properly done job.
