Maintaining the rear shock on your Fenix EVO [paid link] from Fast Suspension is essential to ensure that your bike performs optimally, especially when tackling tough terrains. Over time, the shock’s oil can degrade, leading to decreased performance and a less smooth ride. In this guide, we’ll walk you through a detailed step-by-step process to change the oil in your Fenix EVO [paid link] rear shock, providing the knowledge you need to complete this maintenance task effectively.
Tools Required
- Shock pump
- Allen wrenches [paid link] (sizes specific to your model)
- Torque wrench [paid link]
- Flat-head screwdriver
- 10mm socket wrench
- Small plastic container or tray for draining old oil
- Replacement oil (recommended by Fast Suspension)
- New seals (if applicable)
- Small brushes for cleaning
- Latex gloves (optional)
Preparation
Before beginning the oil change process, it’s crucial to prepare both the bike and the tools. Proper preparation ensures a clean and efficient procedure.
- Remove the Rear Shock: To start, you need to carefully detach the rear shock from the frame. This may require loosening bolts using the appropriate Allen wrenches [paid link] or socket wrenches. Place the shock on a clean surface.
- Secure the Shock: Using a shock stand or a workbench with proper padding, secure the shock in place. This will allow you to work on it without risking damage.
- Drain Old Oil: Place a small container under the shock to catch any oil that might spill during the disassembly process. You should remove the shock’s air valve first to avoid unnecessary mess.
Step-by-Step Oil Change Procedure
1. Remove the Top Cap
Start by using a flat-head screwdriver or the appropriate tool to loosen and remove the top cap of the shock. This part houses the air valve and often contains a nut that will need to be removed with a socket wrench. Be cautious to avoid damaging any internal components.
2. Drain the Old Oil
Once the top cap is removed, gently tilt the shock to allow the oil to drain completely into your container. Depending on the age and condition of the shock, the oil may appear dirty, indicating the need for a full change.
3. Disassemble the Shock
After draining the oil, use the appropriate tools to remove the body from the shock’s damper assembly. You may need to use a 10mm socket wrench for some of the bolts. Carefully note the order of any washers, seals, or spacers, as these will need to be replaced or reused later.
4. Clean the Internal Components
With the shock disassembled, it’s crucial to clean all internal components. Use a small brush to gently clean the damper shaft, piston, and other moving parts. Ensure that all debris, old oil residue, and dirt are completely removed. This is a vital step to prevent any contamination when you refill the shock.
5. Replace the Seals
If your seals appear worn or damaged, now is the time to replace them. Over time, seals can degrade, causing air or oil leakage, which affects shock performance. Fast Suspension recommends replacing seals every few oil changes, depending on riding conditions. Install new seals with caution, ensuring that they fit perfectly into the designated grooves.
6. Reassemble the Shock
Once the components are clean and the seals are replaced, it’s time to reassemble the shock. Carefully align and reassemble the damper assembly with the shock body. Be sure to tighten any bolts or nuts to the manufacturer’s recommended torque specifications. If in doubt, use a torque wrench [paid link] to ensure proper tightness.
7. Refill with New Oil
Fast Suspension suggests using their recommended oil for the Fenix EVO shock. Pour the new oil into the shock according to the specific volume required for your model. Most shocks require a precise amount of oil, so be sure to consult your manual or the manufacturer’s guidelines.
8. Install the Top Cap
Once the shock is refilled with oil, carefully replace the top cap. Tighten it securely to avoid any leaks during use. Be mindful not to over-tighten, as this can damage the threads or seals.
9. Test the Shock
Before reinstalling the shock onto your bike, use a shock pump to re-pressurize the shock to the manufacturer’s recommended pressure. Check for any air or oil leaks, and perform a simple function test by compressing the shock manually. The shock should move smoothly and without resistance.
10. Reinstall the Shock onto Your Bike
Now that the oil change is complete and the shock has been re-pressurized, reinstall it onto the bike. Tighten the bolts to the manufacturer’s torque specifications and ensure that everything is securely fastened.
Troubleshooting Common Issues
Leaking Oil
If you notice oil leaking after the oil change, it’s likely that a seal wasn’t properly seated or there’s an issue with the top cap. Inspect all seals and components to ensure everything is installed correctly.
Poor Shock Performance
If the shock is not performing as expected after the oil change, check the air pressure and verify that the shock was filled with the correct amount of oil. If performance issues persist, inspect the internal components for damage or wear.
Customization and Optimization
Adjusting Shock Pressure
The Fenix EVO shock can be optimized by adjusting the air pressure to suit your specific riding style and terrain. Experiment with different pressure settings to find the ideal balance between comfort and performance.
Fine-Tuning the Rebound
The rebound adjustment controls how quickly the shock returns to its original position after compression. For smoother rides on rough terrains, a slower rebound setting may be ideal, while faster settings are better for aggressive riding styles.
Compatibility with Other Drivetrain Components
The Fenix EVO rear shock is designed to work seamlessly with various types of drivetrain systems. It is important to ensure that your shock is properly tuned to complement the rest of your bike’s suspension and drivetrain setup. For optimal performance, consult with a professional mechanic or Fast Suspension for specific compatibility recommendations.