The Fox DHX2 Trunnion [paid link] rear shock is known for its smooth performance and exceptional durability. However, like all bike components, it requires maintenance and occasional rebuilding to ensure it continues to perform at its best. Whether you’re an experienced mechanic or a DIY enthusiast, this guide will walk you through the process of rebuilding your DHX2 Trunnion [paid link] rear shock at home. By following this detailed, technical guide, you’ll be able to restore your shock to optimal working condition.
Tools Required
- 5mm, 6mm, and 8mm Allen wrenches [paid link]
- Torque wrench [paid link]
- T20 Torx driver
- T25 Torx driver
- 10mm socket wrench
- Shock pump
- Oil (Fox Float fluid or recommended equivalent)
- Grease (Fox High-Performance Fluid)
- Small brushes and rags
- Replacement seals and O-rings (if necessary)
- Cleaning solvent
Disassembly of the DHX2 Trunnion Rear Shock
Step 1: Remove the Rear Shock from the Bike
Before beginning the disassembly process, ensure that the shock is removed from the bike. This requires unbolting the shock from the frame using the appropriate tools. Typically, this involves using a 5mm Allen wrench [paid link] to remove the mounting bolts at both ends of the shock. Once the shock is free, place it on a clean, stable surface.
Step 2: Prepare the Shock for Disassembly
To prevent dirt and contaminants from entering the shock during disassembly, clean the exterior thoroughly with a rag and some solvent. Pay close attention to the shock body, especially around the eyelets and seals.
Step 3: Remove the Trunnion Mounting Hardware
Using a 6mm Allen wrench [paid link], remove the trunnion mounting bolts. Take extra care when handling the trunnion area, as the seals and bearings can be sensitive. Set these parts aside for reassembly.
Step 4: Disassemble the Shock Body
After removing the mounting hardware, begin disassembling the shock. Use a T25 Torx driver to remove the bolts securing the shock body. Once the bolts are removed, gently separate the components, including the air can and shock body. Be cautious of any internal springs or fluid that may spill out during this step.
Inspection of Components
Step 1: Inspect the Air Can
Check the air can for any signs of damage, such as dents or scratches that could impair its function. If the air can is in good condition, it can be reused, but any damage will necessitate replacement.
Step 2: Inspect the Shaft and Seals
Carefully inspect the shock shaft and internal seals for any signs of wear. If the seals appear to be compromised or the shaft is scratched, replace them. The DHX2 Trunnion uses high-quality seals, so replacing them ensures smooth operation and prevents air or oil leakage.
Step 3: Check the Bearings and Bushings
Inspect the bearings and bushings in the trunnion mount for any signs of damage or play. These parts are crucial for maintaining a smooth suspension action and should be replaced if they feel loose or damaged.
Cleaning the Components
Step 1: Clean the Shock Body
Use a cleaning solvent to thoroughly clean the shock body and any internal components. Make sure no dirt or debris remains inside the shock body, as this can cause wear and compromise the performance of the shock.
Step 2: Clean the Air Can
Wipe down the air can with a rag and inspect it for any remaining oil or dirt. If the air can is particularly dirty, use a brush to scrub any hard-to-reach areas.
Step 3: Clean the Shaft and Seal Areas
The shaft and seals should be cleaned gently to avoid damaging them. Use a small brush to remove dirt and oil from the shaft, especially where the seals are located.
Rebuilding the DHX2 Trunnion Rear Shock
Step 1: Reassemble the Shock Body
Once all the components are clean and dry, start reassembling the shock. Begin by inserting any new seals and O-rings into their respective positions. Carefully align the shock body and air can, ensuring everything fits together smoothly.
Step 2: Apply Grease and Oil
Apply a thin layer of Fox High-Performance Fluid or recommended grease to the seals and moving parts to ensure smooth operation. Be cautious not to over-grease, as excess grease can attract dirt and debris.
Step 3: Install the Shaft and Bearings
Install the shock shaft into the shock body, followed by the bearings and bushings in the trunnion mount. Ensure the bearings are properly seated and free from any play.
Step 4: Reinstall the Mounting Hardware
Once the shock body is reassembled, reinstall the trunnion mounting hardware using the appropriate 6mm Allen bolts. Tighten them securely but do not over-tighten, as this can damage the shock body or mounting area.
Filling the Shock with Oil and Air
Step 1: Add the Recommended Oil
The DHX2 Trunnion uses Fox Float fluid or an equivalent for the internal damping. Check the service manual for the exact oil volume required for your shock model. Using a syringe or small funnel, carefully add the required amount of oil into the air can and shock body.
Step 2: Recharge the Shock with Air
Once the oil is added, use a shock pump to charge the shock with air. Be sure to follow the manufacturer’s guidelines for the correct air pressure. Typically, this will involve setting the shock to the desired pressure based on your weight and riding style.
Step 3: Check for Leaks
Before reattaching the shock to the bike, check for any leaks around the seals. Apply gentle pressure to the shock and inspect it for any escaping air or oil. If any leaks are detected, carefully address the issue by adjusting the seals or tightening the components.
Reinstalling the Shock onto the Bike
Step 1: Reattach the Shock to the Frame
Once the shock is rebuilt and fully charged with air, reinstall it onto the bike frame. Use the 5mm Allen wrench to secure the mounting bolts at both ends of the shock. Be sure to torque the bolts to the recommended specifications to avoid over-tightening or under-tightening.
Step 2: Final Check
After reinstalling the shock, perform a final check to ensure that everything is functioning smoothly. Test the rear suspension by pushing down on the saddle to check for proper compression and rebound. If there are any issues, recheck the installation process and ensure all components are properly installed and adjusted.
Troubleshooting Common DHX2 Trunnion Rear Shock Issues
Issue 1: Leaking Air or Oil
If the shock is leaking air or oil, check the seals, O-rings, and air can for damage. Replace any worn or damaged parts to prevent further leaks.
Issue 2: Unresponsive Shock or Poor Performance
If the shock feels unresponsive or exhibits poor performance, it could be due to improper oil levels or air pressure. Ensure that both are set according to the manufacturer’s recommendations. Also, inspect the damping system for any signs of contamination or wear.
Issue 3: No Rebound or Excessive Rebound
If the rebound adjustment is not functioning as expected, the rebound damper may be clogged or damaged. Perform a thorough cleaning and inspection of the damper, and replace any worn components as necessary.
Customization and Optimization Tips
To get the most out of your DHX2 Trunnion rear shock, consider the following tips for customization:
- Adjust the air pressure to suit your weight and riding style. Lighter riders may prefer a lower air pressure, while heavier riders may need a higher pressure for more support.
- Fine-tune the rebound and compression settings based on your riding terrain. Softer settings are ideal for rough terrain, while firmer settings are better for smoother trails.
- Replace the shock oil regularly to maintain performance and prevent damping degradation.
- Experiment with different shock mounting positions to change the overall suspension feel and performance.
Conclusion
Rebuilding your Fox DHX2 Trunnion rear shock at home is a rewarding and cost-effective way to maintain the performance of your bike’s suspension. By following this guide, you’ll be able to disassemble, clean, and rebuild the shock with precision and care. With proper maintenance and tuning, your DHX2 Trunnion will continue to perform at its best, providing a smooth and controlled ride every time you hit the trail.