Replacing the rear axles on your Mercedes Benz W123 can become necessary due to wear and tear, often indicated by noises like clicking during deceleration. This guide, based on practical experience, will walk you through the process of replacing your W123 axles at home. It’s a task that can be accomplished by a DIY enthusiast, saving on garage labor costs and ensuring your classic Mercedes continues to run smoothly. This guide focuses on providing clear steps and crucial advice for a successful Mercedes Benz Axles replacement.
Before you begin, ensure you have the correct replacement axles and consider purchasing new differential to axle seals as a precaution. While the original article sourced axles from Advanced Auto (SKU # 20870644), always verify compatibility with your specific W123 model. Remember, parts can vary, and using the correct Mercedes Benz axles is paramount.
Step-by-Step Mercedes Benz Axle Replacement
This section outlines the process of replacing your Mercedes Benz axles on a W123 model. Safety is paramount, so follow each step carefully.
Step 1: Safety and Lifting the Vehicle
Safety is the most crucial aspect of any DIY car repair. Before you even think about touching any bolts, ensure your vehicle is safely secured.
Image 1: Secure Vehicle with Wheel Chocks.
Begin by placing wheel chocks securely behind the rear wheels of your front tires. This will prevent any accidental rolling of the vehicle while you are working underneath it.
Image 2: Lifting the Mercedes Benz W123 from the Rear Differential.
Next, use a jack to lift the rear of your Mercedes W123. The differential housing is a robust jacking point, especially suitable for a long body jack, allowing you to raise the car from the rear bumper area effectively.
Image 3: Securely Position Jack Stands Under Sub Frame Bushings.
Once the car is raised to a safe working height, place jack stands under the subframe bushing areas. This location provides a secure and stable support point for the W123. After lowering the car onto the stands, vigorously shake the vehicle to ensure the stands are firmly positioned and will reliably hold the car’s weight. If there’s any movement, reposition the jack stands until you are confident in their stability. Working under a securely supported vehicle is non-negotiable for your safety.
Step 2: Differential Preparation
Before you start disconnecting the Mercedes Benz axles, it’s wise to prepare the differential area. This involves cleaning the area to prevent debris from entering the differential once it’s opened.
Image 4: Cleaning the Differential Housing.
Use a pressure washer or degreaser and a brush to thoroughly clean the rear of the differential. Removing dirt and grime will make the job cleaner and prevent contamination. If you’ve recently cleaned your car’s undercarriage, a simple brushing might suffice.
Image 5: Removing the Differential Fill Plug.
Locate and remove the fill plug on the differential using a 14mm Allen socket. It’s always best practice to remove the fill plug before the drain plug. This ensures you can refill the differential later; you don’t want to drain the oil and then find you can’t open the fill plug. In this case, the existing synthetic oil was filtered and reused, as it was relatively new. If your differential oil is old or contaminated, consider replacing it entirely with fresh, high-quality differential oil suitable for Mercedes Benz axles and differentials.
Step 3: Axle Removal and Installation Considerations
Now comes the core part of replacing your Mercedes Benz axles. This involves removing the old axles and installing the new ones.
When removing the old axles, pay close attention to all components, especially the spacers and bolts. A critical point highlighted in the original article is about the wheel hub to axle bolt spacer. It’s crucial to measure the provided spacer against the original one from your vehicle. If your Mercedes Benz axles are original or have been in place for a long time, it’s highly recommended to reuse the original spacer tube. The aftermarket spacers can sometimes be longer, preventing the axle from seating correctly into the wheel hub.
Furthermore, be cautious with the bolts provided with aftermarket Mercedes Benz axles. The original article mentions a bolt breaking during installation. Therefore, consider reusing the original Mercedes-provided bolts, especially if they are in good condition. Mercedes original parts are often manufactured to higher tolerances and material standards.
When installing the new Mercedes Benz axles, ensure they are correctly seated both in the differential and the wheel hub. If you opted to replace the differential to axle seals, now is the time to install them before inserting the new axles into the differential housing. Lubricate the seals and the axle splines with differential oil to aid installation and prevent damage to the seals.
Step 4: Final Steps
After installing the new Mercedes Benz axles and securing them with the bolts and spacers (remembering to potentially reuse the original spacers and bolts), double-check all connections for tightness. Refill the differential with the appropriate amount and type of gear oil through the fill plug you removed earlier. Torque the fill plug to the manufacturer’s specification.
Finally, carefully lower the vehicle from the jack stands. Before taking it for a test drive, it’s wise to manually rotate the wheels to check for any binding or unusual noises. Start with a slow test drive in a safe area, listening for any clicks, noises, or vibrations from the Mercedes Benz axles or the surrounding drivetrain.
Conclusion
Replacing Mercedes Benz axles on a W123 model is a manageable DIY task for those with some mechanical experience. By following these steps and heeding the cautions about spacers and bolts, you can successfully complete this repair. Remember to prioritize safety, use quality parts, and take your time to ensure each step is done correctly. This DIY approach not only saves money but also provides a deeper understanding and appreciation for your classic Mercedes Benz. Always consult your vehicle’s service manual for specific torque specifications and procedures related to your exact model year and variant.
