How to Service Your Bomber CR Trunnion Rear Shock Without a Mechanic

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The Marzocchi Bomber CR Trunnion [paid link] Rear Shock is a high-performance shock absorber designed for aggressive riders and challenging terrains. Proper maintenance and servicing are essential to ensure optimal performance, enhance longevity, and maintain the overall efficiency of the suspension system. This guide will take you through the essential steps of servicing the Bomber CR Trunnion [paid link], from installation and adjustments to troubleshooting common issues, with tips on how to perform the tasks without needing to visit a mechanic.

Tools Required

To service your Bomber CR Trunnion rear shock, you will need the following tools:

  • 8mm and 10mm Allen wrenches [paid link]
  • Torque wrench [paid link]
  • 1.5mm and 2mm Allen wrenches [paid link] (for smaller adjustments)
  • Shock pump
  • Suspension fluid (specific to Marzocchi or equivalent)
  • 15mm spanner wrench
  • Small flathead screwdriver
  • Rags and cleaning supplies
  • Small container for oil and fluids
  • Replacement seals (if needed)
  • Grease (light duty)

Installation of the Bomber CR Trunnion Rear Shock

The Bomber CR Trunnion is designed to offer smooth and responsive performance. Installing the rear shock correctly is the first step in maintaining its longevity and ensuring optimal performance.

  1. Align the Trunnion Mounting Points:
    • Begin by positioning the shock in place on your bike frame. The Bomber CR Trunnion is designed with specific mounting points, and it is crucial to align them precisely with the trunnion brackets on your bike.
    • Check for any debris or dirt in the mounting area that could affect the shock’s installation.
  2. Secure the Mounting Hardware:
    • Insert the mounting bolts through the trunnion brackets and tighten them. Make sure you torque the bolts to the manufacturer’s recommended settings, typically around 10-12Nm.
    • Use a torque wrench [paid link] to ensure the bolts are tightened correctly. Over-tightening can damage the shock, while under-tightening may lead to slippage or reduced performance.
  3. Install the Air Canister:
    • The Bomber CR Trunnion shock uses an air canister for its suspension. Before installing, check the air pressure to make sure it matches the rider’s weight and preferences.
    • Use a shock pump to achieve the desired air pressure. Once the pressure is correct, tighten the air valve cap securely.
  4. Test the Shock Installation:
    • After securing the shock, check for any unusual movements or loose components. Gently compress the shock and confirm that it moves smoothly without any resistance or irregular noises.

Adjusting the Bomber CR Trunnion Rear Shock

Proper adjustment is vital for ensuring comfort and performance. The Bomber CR Trunnion features both rebound and compression adjustments, which can be tailored to individual preferences and riding conditions.

  1. Rebound Adjustment:
    • The rebound adjuster controls how quickly the shock returns to its original position after compression. To adjust, locate the rebound dial on the bottom of the shock.
    • Turn the dial clockwise to slow the rebound and counterclockwise to speed it up. Begin with the mid-range setting and make small adjustments based on the terrain you are riding on.
  2. Compression Adjustment:
    • The compression adjuster influences how the shock reacts to bumps and impacts. You’ll find this adjuster near the top of the shock.
    • Turning the compression dial clockwise will increase compression damping, making the shock stiffer and less sensitive to small impacts. Turning it counterclockwise will allow for more sensitivity and smoother movement on smaller bumps.
  3. Fine-Tuning:
    • Start with the manufacturer’s recommended settings for rebound and compression, then fine-tune based on your personal riding style and conditions.
    • Test ride the bike after each adjustment, ensuring that the shock feels responsive and provides a comfortable ride.

Servicing the Bomber CR Trunnion Rear Shock

Routine servicing will keep your Bomber CR Trunnion performing at its best. Over time, dirt and debris can accumulate in the shock, leading to wear and reduced performance. Regular servicing is essential for maintaining smooth suspension action.

  1. Clean the Shock:
    • Use a clean rag to wipe down the shock after each ride, removing dirt and debris. Pay close attention to the seals and the shaft, as these are the areas most susceptible to wear.
    • Apply a small amount of grease to the mounting hardware and the shock’s moving parts to ensure smooth operation.
  2. Replace Seals:
    • Over time, the seals around the shock’s air canister may wear out, leading to air leakage or contamination of the suspension fluid. If you notice any air loss or reduced performance, it may be time to replace the seals.
    • Carefully remove the old seals using a small flathead screwdriver. Clean the shock’s internal components and apply fresh suspension fluid before installing the new seals.
  3. Change Suspension Fluid:
    • The suspension fluid in the Bomber CR Trunnion absorbs heat and helps maintain smooth performance. To replace the fluid, first remove the air canister from the shock.
    • Drain the old fluid into a container and clean the shock body thoroughly. Refill the shock with new fluid according to the manufacturer’s specifications, ensuring the correct volume and type.

Troubleshooting Common Set-Up Issues

While servicing the Bomber CR Trunnion, you may encounter a few common issues. These can typically be resolved with basic troubleshooting steps.

  1. Shock Feels Too Stiff or Too Soft:
    • If the shock feels too stiff or too soft, first check the air pressure. The Bomber CR Trunnion relies on air pressure to control the shock’s response to impacts, so improper pressure can affect performance.
    • Adjust the air pressure using a shock pump according to your weight and riding style. Typically, heavier riders will require higher pressure, while lighter riders can use lower pressure.
    • If the shock still feels off after adjusting the air pressure, consider revisiting the compression and rebound settings.
  2. Noisy Shock:
    • A noisy shock could indicate an issue with the seals or the need for a lubrication refresh. Remove the shock from the bike, clean it thoroughly, and reapply grease to the moving parts. If the noise persists, inspect the seals for wear and replace them as needed.
  3. Leakage of Air or Fluid:
    • If you notice air or fluid leakage, it could be a sign of damaged seals or a failed O-ring. Inspect the shock carefully, and if needed, replace the seals and O-rings to prevent further leaks.
    • Be sure to also check for any cracks or damage to the shock body, as these can lead to more severe issues.

Customization and Optimization for Better Performance

For riders looking to optimize their Bomber CR Trunnion rear shock, customization can significantly improve both comfort and performance. Here are a few tips for getting the most out of your suspension system.

  1. Tuning for Riding Style:
    • Riders who prefer aggressive trail riding may want to stiffen the shock by increasing the compression damping. This reduces the amount of movement and helps with control on rough terrain.
    • For cross-country or endurance riders, a softer shock with lower compression damping can provide a more comfortable ride over extended distances.
  2. Upgrading Components:
    • While the Bomber CR Trunnion is a high-quality shock, some riders may want to upgrade certain components for better performance. Consider upgrading to a high-flow damper for improved small-bump sensitivity or adding a custom air canister for increased support.

Compatibility with Other Drivetrain Components

The Bomber CR Trunnion rear shock is compatible with a variety of mountain bike frames, but compatibility with other drivetrain components should always be checked before installation. Ensure the shock is compatible with your frame’s mounting configuration, as improper mounting can affect performance.

Additionally, if you have an advanced drivetrain setup with electronic suspension adjustments, such as an SRAM or Shimano system, you may need to ensure that the shock is compatible with those systems. If you’re unsure, consult with the manufacturer or a professional bike mechanic.

By following these steps and tips, you can effectively maintain, adjust, and optimize your Marzocchi Bomber CR Trunnion rear shock, ensuring that it performs at its best for all your rides. Regular maintenance and proper tuning will enhance the longevity and functionality of your shock, providing you with a smoother, more enjoyable biking experience.