Servicing Your DHX2 Trunnion Rear Shock: Tools and Tips

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The Fox DHX2 Trunnion [paid link] rear shock is a high-performance suspension component designed to handle a variety of riding conditions, from aggressive trail riding to downhill races. Like any suspension component, regular maintenance is crucial to keep it performing at its peak [paid link]. This guide provides detailed instructions on servicing the DHX2 Trunnion [paid link] shock, including installation, adjustments, troubleshooting, and optimization.

Tools Required

  • 5mm Allen wrench [paid link]
  • 8mm socket wrench
  • Torque wrench [paid link] (up to 200Nm)
  • Shock pump (compatible with Fox shocks)
  • Suspension oil (Fox recommended)
  • Clean rags or cloth
  • Small flathead screwdriver
  • Teflon grease (optional)
  • Needle-nose pliers
  • 10mm open-end wrench
  • Replacement seals and O-rings (for service)

Installation of the DHX2 Trunnion Rear Shock

Proper installation is crucial for ensuring the DHX2 Trunnion rear shock functions correctly and is free from issues. Follow these steps to correctly install the shock:

  1. Prepare the Bike: Before installing the shock, remove the rear wheel to give yourself enough space to work. Secure the bike in a stable position using a workstand.
  2. Install the Trunnion Mount:
    • The DHX2 Trunnion shock uses a trunnion mount system, which has a wider and more stable interface with the frame than traditional eyelet mounts.
    • Slide the shock into the trunnion mounts on the bike frame. Ensure that the shock is aligned properly with the mounting holes.
    • Insert the mounting bolts and tighten them to the recommended torque specification. For the DHX2, the torque is generally 30Nm, but always consult the manufacturer’s instructions for precise torque values.
  3. Secure the Shock: Once the shock is positioned, use a torque wrench [paid link] to tighten the bolts securely. Tighten the shock hardware in a crisscross pattern to ensure even pressure distribution.
  4. Check for Smooth Movement: Before proceeding, check that the shock moves freely within its mounts. There should be no resistance or excessive play.
  5. Reinstall the Rear Wheel: Once the shock is securely installed, reinstall the rear wheel.

Adjusting the DHX2 Trunnion Rear Shock

Adjusting the DHX2 Trunnion rear shock is essential for optimizing its performance to match your riding style and conditions. The DHX2 offers various adjustments, including compression, rebound, and air pressure. Here’s how to make those adjustments:

Air Pressure

  1. Use a Shock Pump: The DHX2 features air-sprung suspension, so adjusting the air pressure is key for proper shock performance. Attach the shock pump to the air valve.
  2. Set Correct Air Pressure: Follow Fox’s recommended air pressure guidelines based on your rider weight. Start with the baseline pressure, then fine-tune based on your preferences and riding style.
  3. Check Sag: The ideal sag is generally around 25-30% of the total shock travel. You can check sag by sitting on the bike and observing how far the shock compresses.

Compression and Rebound Adjustments

  1. Compression Adjustment:
    • The DHX2 features high and low-speed compression settings.
    • Adjust the high-speed compression to fine-tune how the shock handles impacts, such as jumps or drops. Start with the dial in the middle and adjust based on feedback.
    • Use the low-speed compression dial for setting the shock’s response to smaller bumps and pedaling forces.
  2. Rebound Adjustment:
    • The rebound control on the DHX2 adjusts how quickly the shock returns to its original position after compression.
    • Adjust this setting depending on how fast or slow you want the shock to rebound. A slower rebound may be necessary for faster, rougher terrain to prevent “bucking.”

Maintaining the DHX2 Trunnion Rear Shock

Regular maintenance of your DHX2 Trunnion rear shock ensures longevity and peak [paid link] performance. Here are the basic steps for keeping your shock in top condition:

  1. Clean the Shock Regularly: After each ride, clean the shock with a rag to remove dirt and debris. Pay special attention to the shock’s seals and mounting hardware.
  2. Check for Leaks: Inspect the seals for any signs of oil leakage. If oil is leaking from the shock, it indicates that the seals need to be replaced.
  3. Lubricate the Shock: Lubricate the shock’s moving parts with a small amount of suspension oil to maintain smooth operation. Be careful not to over-lubricate as excess oil can attract dirt.
  4. Replace Seals and O-Rings: Over time, seals and O-rings can wear out, leading to loss of oil or air pressure. Replacing these parts is necessary to maintain optimal shock function. Refer to the Fox maintenance manual for part numbers and replacement instructions.
  5. Service Intervals: For optimal performance, Fox recommends servicing your DHX2 shock every 50 hours of riding or at least once per season, whichever comes first. However, this may vary based on your riding conditions.

Troubleshooting Common Set-Up Issues

Even with regular maintenance, issues may arise with your DHX2 Trunnion rear shock. Here are some common problems and how to resolve them:

Lack of Rebound

  • Possible Cause: If the rebound feels too slow or non-existent, it could be due to low air pressure or a malfunctioning rebound adjuster.
  • Solution: Check the air pressure and adjust it if necessary. If the problem persists, the rebound damper might need servicing or replacement.

Too Stiff or Too Soft

  • Possible Cause: If the shock feels too stiff or too soft, it could be caused by improper air pressure or incorrect compression settings.
  • Solution: Adjust the air pressure according to your weight and riding style. Fine-tune the compression settings for better control.

Oil Leaks

  • Possible Cause: Oil leaks are often caused by worn seals or O-rings.
  • Solution: Inspect the seals for damage or wear. Replace any damaged seals, ensuring the shock is properly reassembled afterward.

Customization and Optimization for Better Performance

The DHX2 Trunnion rear shock is highly customizable, allowing riders to tune it to their specific preferences. Here are some tips to optimize your shock for better performance:

  1. Adjusting for Different Terrain: If you ride a mix of downhill and technical trails, set the high-speed compression slightly stiffer to handle larger impacts, while keeping the low-speed compression softer for better small-bump sensitivity.
  2. Tuning for Weight and Riding Style: Lighter riders might benefit from slightly lower air pressure for a more supple ride, while heavier riders may require higher pressure for optimal performance. Test different pressures and settings to find the balance that works best for you.
  3. Air Can Volume: The DHX2 allows for air volume adjustments. Experiment with the volume spacers to modify the shock’s progression, making it either more linear or more progressive, depending on your preference.

Compatibility with Other Drivetrain Components

The DHX2 Trunnion rear shock is designed to be compatible with most modern mountain bike drivetrains. However, when setting up the shock, it’s important to ensure that the overall suspension geometry of the bike is suited to your drivetrain and riding style. Adjusting the rear shock’s compression and rebound can affect how the rear triangle reacts during pedaling, so finding the right balance is essential for a smooth and efficient ride.

The DHX2 shock can be paired with most frames featuring a trunnion mount, but always verify compatibility with the frame’s specifications. Additionally, matching your shock settings with the type of rear derailleur, cassette, and chainring you use can help ensure optimal pedaling efficiency and suspension response.