Here's a general overview of the steps involved. Remember safety first! Use jack stands, wear safety glasses, and disconnect the battery's negative terminal.
1. Preparation:
* Gather Tools: You'll need jack stands, a jack, wheel chocks, socket set (including deep sockets), a torque wrench, a pry bar, a ball joint separator, possibly a CV joint separator, a large drain pan, penetrating oil (PB Blaster is a good option), and possibly a new axle nut.
* Raise and Secure the Vehicle: Safely lift the Envoy and securely support it with jack stands. Always use wheel chocks on the wheels that remain on the ground.
* Remove the Wheel: Remove the wheel from the affected side.
2. Disconnect Components:
* Disconnect the ABS Sensor: Carefully disconnect the ABS sensor wire harness from the half shaft.
* Disconnect the Brake Caliper: Use a suitable socket to remove the caliper bolts and carefully hang the caliper out of the way, ensuring the brake line doesn't get stretched or damaged. You may need to use a wire or bungee cord to secure it.
* Disconnect the Sway Bar Link: Remove the sway bar link from the control arm. You'll likely need a wrench and possibly a ball joint separator.
* Disconnect the Tie Rod End: This often requires a tie rod separator tool. Note the position and count the number of turns before removing to aid in reassembly.
* Remove the Axle Nut: This can be very tight. Use a breaker bar or impact wrench if necessary. Mark the axle nut's position relative to the half shaft for easier reinstallation.
3. Remove the Half Shaft:
* Separate the CV Joint from the Transmission/Differential: This is often the most challenging part. You may need to use a CV joint separator tool or a combination of pry bars and other techniques to carefully separate the joint from the transmission or differential. Be gentle to avoid damage.
* Remove the Half Shaft: Once the CV joint is separated, the half shaft should come out relatively easily. You may need to gently wiggle it free.
4. Install the New Half Shaft:
* Installation is generally the reverse of removal. Ensure the new half shaft is properly seated in the transmission/differential and the CV joint is correctly connected to the wheel hub.
* Tighten all components to the manufacturer's specified torque. Consult a repair manual for the correct torque specifications. Use a torque wrench to ensure proper tightening.
* Reconnect all previously disconnected components.
5. Lower and Test:
* Lower the vehicle: Carefully lower the vehicle to the ground.
* Inspect your work: Double-check all connections and tightenings.
* Test drive: Take the Envoy for a short test drive to ensure everything is working correctly. Listen carefully for any unusual noises.
Important Considerations:
* Wheel Bearing: Inspect the wheel bearing while the half shaft is out. If it shows any signs of wear or damage, replace it as well.
* CV Joint Boots: Inspect the CV joint boots for any tears or damage. If damaged, replace the entire half shaft to prevent grease leakage and subsequent damage.
* Repair Manual: This process is significantly easier with a repair manual specific to your 2003 GMC Envoy. This provides detailed diagrams and torque specifications.
This is a complex repair, and mistakes can lead to serious damage or injury. If you are not comfortable performing this repair yourself, it is highly recommended that you take your vehicle to a qualified mechanic.
