Servicing Your Bomber CR Trunnion Rear Shock: Tools and Tips

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The Marzocchi Bomber CR Trunnion [paid link] rear shock is a reliable and high-performance component favored by mountain bikers for its exceptional damping and durability. Regular servicing and maintenance of this shock are essential to ensure it performs optimally throughout its lifespan. This comprehensive guide will walk you through the necessary steps for servicing, adjusting, and troubleshooting the Bomber CR Trunnion [paid link] rear shock, as well as providing tips for customization and optimization.

Tools Required

  • Marzocchi CR Trunnion Service Kit: Includes seals, oil, and other components required for servicing.
  • Torque Wrench [paid link]: For applying the correct torque values.
  • Allen Wrenches [paid link]: Typically 3mm, 5mm, and 6mm sizes.
  • Oil Drain Pan: To catch any excess oil during servicing.
  • Suspension Fluid: Ensure you use the recommended oil type for Marzocchi shocks.
  • Seal Grease: To lubricate seals and O-rings.
  • Shock Pump: For adjusting air pressure.
  • Rags and Cleaning Supplies: To keep the shock and surrounding areas clean.
  • Funnel: For easy oil filling.
  • Plastic Scraper: To remove old seals or oil without damaging the shock.
  • Small Brush: For cleaning shock internals.

Servicing the Bomber CR Trunnion Rear Shock

1. Preparing the Shock

Before servicing your Bomber CR Trunnion, make sure you have all the necessary tools and a clean, well-lit workspace. Begin by removing the shock from the bike, taking care not to damage any surrounding components.

  • Remove the Shock from the Frame: Use your Allen wrenches [paid link] to carefully remove the bolts securing the shock to the frame. Make sure to note the orientation of the shock so it can be reinstalled correctly later.
  • Drain the Air Pressure: Use a shock pump to remove any air from the shock’s air chamber. This step is essential before disassembling the shock.

2. Disassembling the Shock

Once the shock is removed and depressurized, the next step is to disassemble it for cleaning and maintenance.

  • Remove the Trunnion Mount: The Bomber CR Trunnion shock uses a trunnion mount, which requires careful attention during removal. Use a torque wrench [paid link] to loosen and remove the trunnion mount screws.
  • Disassemble the Shock Body: Depending on the servicing kit, you may need to remove various screws and nuts to open the shock body. Take note of the order and orientation of each part to facilitate reassembly.
  • Inspect the Internal Components: Carefully check the internal components, including the piston, damper assembly, and air canister, for wear, damage, or excessive dirt buildup.

3. Cleaning and Inspection

Proper cleaning is crucial for the longevity of the Bomber CR Trunnion shock.

  • Clean All Components: Use a small brush and rag to remove any dirt and debris from the shock internals. Be gentle to avoid damaging the delicate components.
  • Inspect Seals and Bushings: Check the seals and bushings for signs of wear or damage. If any components are damaged or excessively worn, they must be replaced. The service kit should include the necessary replacement parts.
  • Inspect the Air Canister and Piston: Check for any signs of oil leakage or unusual wear. Ensure the piston is free of debris and moves smoothly within the shock body.

4. Reassembling the Shock

Once everything has been thoroughly cleaned and inspected, it’s time to reassemble the shock.

  • Lubricate Seals: Apply a small amount of seal grease to the new seals before installing them. This helps prevent air leaks and ensures a smooth operation.
  • Reassemble the Shock: Follow the reverse order of disassembly to reassemble the shock. Take your time to ensure that all parts are correctly oriented and securely fastened.
  • Torque the Bolts: Use a torque wrench to tighten the screws to the manufacturer’s specified torque values. Over-tightening or under-tightening can cause damage to the shock or compromise its performance.

5. Refilling with Oil

The Bomber CR Trunnion shock requires the correct type and amount of oil to function properly. Ensure that you’re using the suspension fluid recommended by Marzocchi for your specific model.

  • Refill the Shock Body: Once the shock is reassembled, refill the shock body with the appropriate oil. Use a funnel for easier pouring and to avoid spills.
  • Recheck Oil Levels: After filling, check the oil level against the manufacturer’s specifications to ensure you’re within the correct range.

6. Reinstalling the Shock

With the shock reassembled and refilled with oil, it’s time to reinstall it on your bike.

  • Install the Shock into the Frame: Position the shock back into the frame, ensuring the correct orientation of the shock and the trunnion mount.
  • Tighten the Bolts: Use your torque wrench to tighten the bolts securing the shock to the frame. Make sure they are tightened to the specified torque values to avoid loosening during rides.

Adjusting and Fine-Tuning the Bomber CR Trunnion Rear Shock

Once the shock is serviced and reinstalled, you’ll want to adjust it for optimal performance based on your weight, riding style, and terrain. The Bomber CR Trunnion comes with various adjustment features, including rebound, compression, and air pressure settings.

1. Adjusting the Air Pressure

The Bomber CR Trunnion uses an air chamber for support. Adjusting the air pressure is critical for achieving the correct sag and ride feel.

  • Check Manufacturer’s Recommendations: Refer to Marzocchi’s specifications for the ideal air pressure range for your weight and riding style.
  • Use a Shock Pump: Attach a shock pump to the air valve and adjust the pressure as needed. Be sure to check the sag by sitting on the bike to ensure the shock compresses adequately.

2. Rebound Adjustment

The rebound adjustment controls the speed at which the shock returns to its original position after compression. Proper rebound settings prevent harsh bouncing or excessive damping.

  • Fine-Tune the Rebound: Adjust the rebound dial on the shock to your preference. Slower rebound is ideal for rough terrain, while faster rebound can be useful for smoother rides.

3. Compression Adjustment

Compression damping affects how the shock reacts to bumps and impacts. Fine-tuning this setting can improve ride quality and bike handling.

  • Adjust Compression: Use the compression dial to adjust the shock’s firmness. Increase compression for more aggressive riding or reduce it for a softer ride.

Troubleshooting Common Issues with the Bomber CR Trunnion Rear Shock

Despite regular maintenance, certain issues may arise with your Bomber CR Trunnion rear shock. Here are some common problems and their solutions:

1. Leaking Oil

If you notice oil leaking from the shock, it may indicate worn seals or a damaged oil seal head.

  • Solution: Replace the seals and ensure that the oil seal head is securely fitted.

2. Loss of Air Pressure

If your shock is losing air pressure, it may be due to a damaged air valve, seal, or improper assembly.

  • Solution: Inspect the air valve and seals for any signs of damage. Replace any faulty components.

3. Excessive Rebound or Slow Compression

If your shock rebounds too quickly or compresses too slowly, it may be due to improper settings or low oil levels.

  • Solution: Adjust the rebound and compression settings. If the issue persists, consider servicing the shock again to check for oil leaks or internal damage.

Customization and Optimization for Performance

The Bomber CR Trunnion rear shock offers numerous ways to fine-tune and optimize your bike’s performance for specific riding conditions.

  • Custom Damping Settings: Experiment with the rebound and compression settings to match your preferred riding style. For aggressive riding, stiffer settings may be necessary, while lighter settings may be more appropriate for cross-country or endurance rides.
  • Consider Air Spring Modifications: Some riders may opt for different air spring modifications for specific needs, such as a more progressive or linear spring curve.

Comparison with Similar Models

The Marzocchi Bomber CR Trunnion is often compared to other high-performance rear shocks, such as the Fox Float X2 and RockShox Super Deluxe. While each model offers unique features, the Bomber CR Trunnion stands out for its simplicity, reliability, and value for money.

  • Fox Float X2: Known for its precision and adjustability, but typically comes at a higher price point.
  • RockShox Super Deluxe: Offers similar performance but may have slightly different compression and rebound adjustment features.

Ultimately, the choice between these models depends on your specific needs and budget.

Understanding Compatibility with Other Drivetrain Components

The Bomber CR Trunnion rear shock is designed to work seamlessly with various drivetrain components. However, ensuring compatibility with your frame, suspension fork, and wheels is crucial for optimal performance. Always check the specifications provided by Marzocchi and other manufacturers to ensure compatibility before installation.