DIY Maintenance Guide for Your DHX2 Trunnion Rear Shock

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The Fox DHX2 Trunnion [paid link] rear shock is a high-performance component designed for aggressive trail riders and downhill enthusiasts. Known for its durability, adjustability, and superior damping performance, the DHX2 is a critical part of your bike’s suspension system. Regular maintenance and adjustments ensure it continues to perform at its best, providing optimal support and comfort during rides. This DIY guide will take you through the essential steps for installing, maintaining, troubleshooting, and customizing your DHX2 Trunnion [paid link] rear shock.

Tools Required

  • 8mm hex wrench
  • 10mm hex wrench
  • 5mm Allen wrench [paid link]
  • Torque wrench [paid link] (up to 10Nm)
  • Suspension fluid (Fox Float Fluid or equivalent)
  • Cleaning supplies (rags, brush, degreaser)
  • A shock pump
  • Shock pump bleed kit [paid link] (optional)
  • Soft vice or shock clamp (optional)

Installation of the DHX2 Trunnion Rear Shock

Installing your DHX2 Trunnion rear shock correctly ensures optimal performance and longevity. Here are the key steps:

  1. Remove the Old Shock:
    • Begin by removing the old shock from the bike. Use the appropriate wrenches to loosen the mounting bolts at both ends of the shock. Keep the washers and bolts for reinstallation if they are in good condition.
    • Carefully slide the shock out of the frame. Be cautious not to damage any suspension components or frame parts.
  2. Prepare the New DHX2 Trunnion Rear Shock:
    • Inspect the DHX2 shock for any visible damage, ensuring the shock is intact and free of leaks. Make sure the air sleeve is properly installed and that all mounting hardware is in good condition.
  3. Install the Shock into the Frame:
    • Align the shock’s eyelet with the frame’s mounting points, ensuring the trunnion mount is correctly oriented. Depending on the bike’s design, the trunnion mount might need specific alignment to fit properly.
    • Tighten the mounting bolts by hand before securing them with a torque wrench [paid link]. Use the manufacturer’s recommended torque settings (typically around 8-10Nm for Fox shocks).
  4. Check for Proper Fit:
    • Ensure that the shock is seated correctly, with no movement or play at either mount. This will prevent unwanted noise or wear during use.

Adjustment and Tuning of the DHX2 Trunnion Rear Shock

The DHX2 Trunnion rear shock features a wide range of adjustments to suit different riding styles and terrain conditions. Properly tuning your shock is crucial for achieving a smooth, controlled ride. Here’s how you can adjust it:

1. Sag Setup

  • Begin by adjusting the sag to match your weight and riding style. Use a shock pump to set the correct air pressure for your weight. Typically, the sag for a rear shock should be about 30% of the total shock travel.
  • To measure sag, sit on your bike and compress the suspension. Measure the distance the shock compresses and adjust the air pressure until you reach the desired sag.

2. Rebound Adjustment

  • The rebound adjustment controls the speed at which the shock returns after compressing. Turn the rebound dial clockwise for slower rebound and counterclockwise for faster rebound.
  • Start with a middle setting and make small adjustments during rides to fine-tune the feel. Too fast a rebound can lead to instability, while too slow can make the bike feel sluggish.

3. Compression Adjustment

  • The DHX2 features both high-speed and low-speed compression adjustments. High-speed compression controls the shock’s response to big hits, while low-speed compression affects the shock’s performance on smaller bumps and pedal strokes.
  • Begin with the low-speed compression set to mid-range and adjust based on the terrain. For more aggressive riding or downhill conditions, increase compression to prevent bottoming out.

4. Lockout Feature (if applicable)

  • Some DHX2 models feature a lockout function to prevent suspension movement during climbing or when riding on smooth, flat terrain.
  • Test the lockout on a flat surface, ensuring the shock is fully locked out when needed for efficient pedaling.

Maintenance of the DHX2 Trunnion Rear Shock

Routine maintenance is essential for keeping your DHX2 Trunnion rear shock in optimal condition. The following steps will help extend the life of your shock and maintain peak [paid link] performance.

1. Clean the Shock

  • Regularly clean the shock with a mild degreaser and a soft brush to remove dirt, debris, and grime. Pay special attention to the seals and mounting hardware.
  • Avoid using harsh chemicals that could damage the shock’s finish or seals. Dry the shock with a clean rag after cleaning.

2. Inspect for Leaks or Damage

  • Inspect the shock for any signs of leakage around the air shaft, seals, or mounting points. If any leaks are detected, you may need to replace the seals or have the shock serviced by a professional.
  • Check for visible dents, scratches, or cracks on the shock body. These could compromise the shock’s performance and safety.

3. Re-grease the Shock Mounting Points

  • Apply a light layer of grease to the shock mounting points. This helps prevent corrosion and reduces friction during suspension movement.
  • Be careful not to over-grease, as excess grease can attract dirt and cause issues.

4. Rebuild the Shock (Annually or as Needed)

  • If you ride frequently or in harsh conditions, it’s important to service your shock at least once a year. Fox recommends a full rebuild of the DHX2 Trunnion every 50-100 hours of riding, depending on usage.
  • A rebuild typically involves replacing the seals, checking the internal damper, and replenishing the oil in the shock. Fox offers rebuild kits, or you can have your shock professionally serviced by an authorized technician.

Troubleshooting Common Set-up Issues

Sometimes, even after installation and tuning, you may encounter issues with your DHX2 Trunnion rear shock. Here are some common problems and their solutions:

1. Shock Not Holding Air Pressure

  • If your shock is losing air, check for a damaged air seal. Inspect the shock’s Schrader valve for leaks and make sure the valve is properly sealed.
  • If air continues to leak, you may need to replace the seals or consult a professional for a rebuild.

2. Bottoming Out

  • If the shock bottoms out too frequently, this may be a sign that your air pressure is too low or your compression settings are too soft.
  • Increase the air pressure and adjust the compression damping settings until the shock provides adequate support.

3. Excessive Rebound

  • If the shock rebounds too quickly, causing instability or loss of control, increase the rebound damping by turning the rebound dial clockwise.
  • If the rebound feels too slow, decrease the rebound damping by turning the dial counterclockwise.

4. Noise or Unusual Movement

  • If you hear creaking or feel unusual movement in the shock, check the mounting bolts for tightness. Loose bolts can cause unwanted noise and affect shock performance.
  • Ensure that the shock is properly aligned in the frame and that the mounts are not worn or damaged.

Customization and Optimization

To get the best performance out of your DHX2 Trunnion rear shock, consider the following customization options:

1. Tune for Your Riding Style

  • Adjust the shock based on your riding style and terrain. If you ride mostly downhill or enduro, you may want to increase compression damping to handle big hits. If you focus on trail riding or cross-country, a lighter setting may provide better efficiency and comfort.

2. Experiment with Air Volume Spacers

  • The DHX2 allows you to add or remove air volume spacers to adjust the shock’s progressivity. Adding spacers can help reduce bottoming out on big impacts, while removing them makes the shock feel more linear and responsive.

Compatibility with Other Drivetrain Components

The DHX2 Trunnion rear shock is compatible with a wide range of bikes, but it’s important to ensure that your bike frame and suspension linkage are designed for a trunnion-mounted shock. Compatibility depends on the frame’s shock mount design and the stroke length of the shock. Always check the specifications of both the shock and the frame to ensure they work together smoothly.