How to Rebuild Your Bomber Air Trunnion Rear Shock at Home

Rebuilding your Marzocchi Bomber Air Trunnion rear shock at home is a rewarding process that can greatly extend the lifespan and performance of your shock. Whether you’re looking to freshen up the suspension for smoother rides or troubleshoot issues like air loss or poor performance, this guide will walk you through each step with detailed instructions. By the end of this article, you’ll know how to properly rebuild, adjust, and maintain your shock, ensuring that your bike is ready for any trail.

Tools Required

Marzocchi Bomber Air Trunnion shock rebuild kit
Shock pump (compatible with your shock)
8mm and 10mm socket wrenches
Torque wrench [paid link] (to ensure proper tension)
Small flathead screwdriver
Allen wrench [paid link] set (4mm, 5mm, 6mm)
Clean rags or paper towels
Isopropyl alcohol (for cleaning)
Suspension grease
Air compressor or shock oil
Pliers (optional)
Latex gloves (to keep components free from oil and dirt)

Understanding the Bomber Air Trunnion Rear Shock

The Marzocchi Bomber Air Trunnion rear shock is a premium shock designed for aggressive riders and those who demand high-performance suspension systems. It features a trunnion mount system, providing more consistent performance and greater shock longevity. The shock uses an air spring and an advanced damper system to ensure optimal control and comfort.

This shock can be rebuilt and serviced at home, provided you have the right tools and knowledge. Regular maintenance will prevent premature wear and improve ride quality, especially for riders who tackle rough terrains and technical trails.

Step-by-Step Guide to Rebuilding the Bomber Air Trunnion Rear Shock

1. Prepare the Shock for Disassembly

Before you begin, ensure the bike is stable and securely positioned. Use a bike stand [paid link] or another secure setup to prevent the bike from tipping over during the rebuild process. It’s crucial to deflate the shock entirely before starting the disassembly.

Release the air pressure from the shock by using a shock pump. Carefully remove any air from the shock until it is fully deflated.
Once the air is released, clean the shock with a clean rag and isopropyl alcohol to remove dirt and debris. This step helps prevent any contaminants from entering the shock during disassembly.

2. Remove the Shock from the Frame

Using an 8mm socket wrench, loosen the mounting bolts that attach the shock to the frame.
Carefully slide the shock off the frame and set it on a clean surface. Make sure the shock’s mounting hardware is securely placed in a safe area for reinstallation later.

3. Disassemble the Shock

Now that the shock is removed from the bike, it’s time to start the disassembly.

Begin by removing the shock’s air valve using the correct tool, typically a small flathead screwdriver. This is essential for draining any residual air pressure left inside.
Remove the top cap or any other components that are held in place with screws. Depending on the model, you might need to use an Allen wrench [paid link] (5mm or 6mm) to loosen any bolts or screws.
Pay attention to the order of the components as you remove them. It’s a good idea to lay out each part in the same order they are removed, ensuring easy reassembly later.

4. Inspect Internal Components

Once you’ve disassembled the shock, it’s time to check the internal components for wear or damage. This step is essential for identifying parts that need replacement.

Air canisters and seals: Inspect the seals for any signs of cracking, wear, or dirt buildup. Any damaged seals will need to be replaced to prevent air leaks.
Damper assembly: Check the damper for any signs of oil leakage or contamination. This is a critical component for shock performance, so any issues here will affect the performance.
Shaft and piston: Ensure that the shock shaft and piston are not bent or damaged. If they are, they will need to be replaced.

If any parts are damaged, it’s important to replace them with the appropriate parts from the Bomber Air Trunnion rebuild kit.

5. Clean the Components

Use clean rags or paper towels and isopropyl alcohol to thoroughly clean all parts of the shock, including the shaft, air canisters, damper, and seals. Be sure to remove any dirt, oil, or grease that may have accumulated inside the shock.

Cleanliness is critical during the rebuild process. Contaminants inside the shock can cause long-term damage or affect its performance.

6. Reassemble the Shock

Now that all components are cleaned and inspected, it’s time to reassemble the shock.

Install the new seals: Begin by carefully installing the new seals from the rebuild kit. Use a small amount of suspension grease to lubricate the seals before installation to ensure smooth movement and proper sealing.
Reinstall the damper: Once the seals are in place, carefully reinstall the damper assembly into the shock body.
Reattach the top cap and air valve: Secure the top cap and air valve, ensuring that everything is tightened to the manufacturer’s torque specifications.
Install the piston and shaft: Carefully insert the piston and shaft assembly, making sure it moves freely and is properly aligned.

7. Reinflate the Shock and Check for Leaks

After the shock has been fully reassembled, it’s time to reintroduce air pressure.

Use a shock pump to inflate the shock to the recommended pressure based on your weight and riding style. The correct air pressure is crucial for proper suspension performance.
Once the shock is inflated, check the shock for any air leaks. If you notice any air escaping, you may need to disassemble the shock again to address the issue.

8. Reinstall the Shock on the Bike

Now that the shock is fully reassembled and pressurized, you can reinstall it onto the bike.

Position the shock back onto the frame, ensuring that the mounting bolts align properly.
Tighten the mounting bolts to the specified torque settings, making sure the shock is securely in place.

9. Perform Final Adjustments

Once the shock is reinstalled, perform any final adjustments to ensure it’s set up correctly for your ride.

Adjust the rebound and compression settings as needed based on your riding preferences.
Test the shock by compressing it a few times to make sure everything is functioning smoothly.

10. Test Ride and Fine-Tuning

After the rebuild and adjustments are made, it’s important to test the shock on the trail. Take the bike for a short ride to ensure the shock is working properly. During your ride, pay attention to the shock’s performance, such as how it absorbs bumps and maintains consistent damping.

If necessary, make additional fine-tuning adjustments to the rebound or compression settings until you achieve the desired performance.

Troubleshooting Common Set-Up Issues

Air Pressure Issues

Problem: The shock feels too stiff or too soft.
Solution: Adjust the air pressure to match your body weight and riding style. Too little air pressure will make the shock feel too soft, while too much air pressure will make it feel overly stiff.

Leaking Air

Problem: The shock is losing air pressure.
Solution: Inspect the seals, air valve, and other components for any signs of damage. Replace worn-out seals immediately, as they are the most common cause of air loss.

Poor Damping Performance

Problem: The shock doesn’t provide smooth damping or feels inconsistent.
Solution: Check the damper assembly for contamination or damage. If necessary, replace the damper oil or the damper assembly itself.

Customization and Optimization for Better Performance

Optimizing your Bomber Air Trunnion rear shock involves adjusting the air pressure, compression, and rebound settings to suit your riding style and terrain.

Air Pressure: Adjust the air pressure based on your weight and preferences. Lighter riders typically need lower air pressure, while heavier riders may require higher air pressure.
Compression Damping: Fine-tune the compression settings to control how the shock reacts to impacts. If you ride aggressive trails, a firmer compression setting can improve control.
Rebound Damping: Adjust the rebound to ensure the shock returns smoothly after compressing. A slower rebound helps keep the bike stable on technical descents.

Conclusion

Rebuilding your Marzocchi Bomber Air Trunnion rear shock at home is an effective way to ensure it remains in top condition. By following this step-by-step guide, you can perform essential maintenance, troubleshoot common issues, and optimize your shock for peak performance. With regular maintenance and proper care, your Bomber Air Trunnion rear shock will continue to deliver exceptional performance for years to come.