The Fox DHX Factory [paid link] rear shock is a premium, high-performance shock designed for aggressive riders and serious downhill enthusiasts. Regular maintenance is crucial for ensuring optimal performance, and one of the most important tasks is performing an oil change. This guide will take you through the step-by-step process of changing the oil in your DHX Factory [paid link] shock to keep it working at its best.

Tools Required

• Fox rear shock pump
• Fox oil (specifically for DHX shocks)
• 5mm Allen wrench [paid link]
• 8mm spanner wrench
• Oil drain pan
• Isopropyl alcohol (for cleaning)
• Clean rags or paper towels
• Torque wrench [paid link]
• Safety gloves
• Clean container for old oil

Preparation

Before starting the oil change, it’s essential to prepare your workspace and gather the necessary tools. Make sure you are in a clean, well-lit area to avoid contaminating the shock with debris or dirt. Wearing safety gloves is recommended to protect your hands from oil and chemicals.

Remove the Shock from the Bike

1. Use a 5mm Allen wrench [paid link] to remove the bolts holding the shock in place.
2. Carefully detach the shock from the frame, ensuring not to damage any other components.
3. Place the shock in a clean, stable area to prevent any damage during the oil change.

Drain the Old Oil

The first step in changing the oil is to remove the old fluid from the shock. Over time, shock oil can degrade, which affects performance. Draining the oil ensures that you start with a fresh, clean setup.

Step-by-Step Procedure

1. Position the Shock: Lay the shock horizontally with the damper side facing up. This positioning helps to avoid oil spillage during the draining process.
2. Remove the Air Valve: Use the Fox rear shock pump to release any air pressure in the shock. Make sure to completely deflate it before proceeding.
3. Open the Oil Reservoir: Using the 8mm spanner wrench, carefully remove the oil reservoir cap. Be cautious, as this will release pressure from the shock. Have your oil drain pan ready to catch any fluid that comes out.
4. Drain the Oil: Allow the oil to drain completely into the pan. This process may take a few minutes to ensure all the fluid is released.

Clean the Shock Components

Once the old oil has drained, it’s crucial to clean the shock and its components to prevent any debris from contaminating the new oil.

Cleaning Steps

1. Clean the Reservoir: Use isopropyl alcohol and a clean rag to wipe down the oil reservoir. This helps remove any dirt or oil residue from the inside of the shock.
2. Check for Debris: Inspect the shock’s internal components for any dirt, dust, or grime. If any debris is present, clean it thoroughly to ensure smooth operation once the new oil is in.
3. Inspect the Seals: Check the seals for wear or damage. If the seals are worn out, it’s essential to replace them to prevent leaks and ensure optimal shock performance.

Refill the Shock with New Oil

Once the shock is clean and free of old oil, it’s time to add the new oil. The DHX Factory shock requires a specific type of oil, typically Fox Fluid, which is specially designed for these shocks.

Refilling Procedure

1. Prepare the New Oil: Open the fresh oil and prepare the necessary amount for your shock model. Fox recommends using the exact fluid amount as specified in the shock’s manual to maintain proper function.
2. Fill the Reservoir: Slowly pour the new oil into the reservoir, ensuring not to spill. It’s essential to pour the oil steadily to avoid air bubbles. The exact amount can be found in the shock’s maintenance guide.
3. Reattach the Reservoir Cap: Once the oil is in, replace the reservoir cap and tighten it using your 8mm spanner wrench. Be sure not to overtighten, as this could damage the threads.

Reassemble and Reinstall the Shock

After filling the shock with new oil, it’s time to reassemble the shock and reinstall it on your bike.

Reinstallation Steps

1. Reinflate the Shock: Use your Fox rear shock pump to inflate the shock to the recommended pressure. The ideal pressure will depend on your rider weight and riding style, so consult your shock’s manual for the correct setting.
2. Reattach the Shock to the Bike: Carefully reinstall the shock on the bike, aligning it with the mounting points on the frame. Tighten the bolts securely using your 5mm Allen wrench.
3. Torque the Bolts: Use a torque wrench [paid link] to ensure that the shock bolts are tightened to the proper specification. This step is critical to prevent the shock from coming loose during riding.
4. Check for Leaks: Before taking the bike out, check the shock for any signs of oil leakage. If you notice any leakage, you may need to recheck the seals or the cap for proper installation.

Final Check and Test Ride

With the oil change complete, it’s time to test the shock and ensure everything is functioning properly.

1. Bounce Test: Push down on the rear of the bike and let the shock rebound. Check for smooth, consistent movement. Any stuttering or sticking could indicate an issue with the oil or seals.
2. Test Ride: Go for a short test ride to feel the shock’s performance. Pay attention to any unusual sounds or behavior. If you experience issues, recheck the shock’s air pressure, oil level, and seals.

Troubleshooting Common Issues

While the oil change process is straightforward, there are a few common issues that may arise during or after the oil change.

Air Bubbles in the Oil

Air bubbles can affect the shock’s performance, leading to poor damping. If you suspect air bubbles are present, try tapping the shock lightly to dislodge them or carefully release and refill the oil reservoir.

Shock Not Rebounding Properly

If the shock does not rebound correctly after the oil change, double-check the oil level and make sure it is filled to the proper capacity. Insufficient oil can prevent the shock from performing optimally.

Leaking Oil

If you notice oil leaking after installation, it could be a sign that the reservoir cap or seals were not properly tightened. Recheck the assembly and ensure that all components are securely in place.

Conclusion

Performing a rear shock oil change on the Fox DHX Factory model is a relatively simple task that can significantly enhance the performance and longevity of your shock. By following the steps outlined in this guide, you’ll ensure that your shock remains in top condition for optimal riding performance. Regular oil changes, along with proper cleaning and maintenance, will keep your DHX Factory shock working smoothly and efficiently for years to come.