The Fenix COIL [paid link] rear shock from Fast Suspension is known for its superior performance, durability, and precision. Regular maintenance, including an oil change, is essential to ensure the shock operates at its peak [paid link] performance. In this guide, we’ll walk you through the process of performing an oil change for the Fenix COIL [paid link] rear shock. This task involves draining the old oil, cleaning the internals, and refilling with fresh suspension oil. Proper oil maintenance will help maintain consistent performance, smoothness, and longevity.
Tools Required
- Suspension fluid (check manufacturer specifications for correct type and volume)
- 10mm and 17mm wrenches
- T25 and T30 Torx screwdrivers
- Shock pump
- Clean cloths or rags
- Oil catch basin
- Small plastic funnel
- Rubber gloves
- A 3mm allen wrench [paid link]
- A torque wrench [paid link]
- Torque specifications for your model
- Sealant (if required by the shock model)
- A shock-specific rebuild kit (including seals and o-rings, if needed)
Step 1: Prepare the Work Area
Before starting, it’s important to ensure that your workspace is clean and free of debris. Have all the necessary tools and replacement parts readily available. Lay down a clean towel or cloth on your work surface to avoid contamination. Wear rubber gloves to maintain a clean environment and to prevent oil from getting onto your hands.
Step 2: Remove the Rear Shock from the Bike
To begin the oil change process, you’ll first need to remove the Fenix COIL rear shock from the bike frame. Start by releasing the mounting bolts at both ends of the shock. Depending on your bike, these may be located at the top or bottom of the shock linkage. Use a 10mm or 17mm wrench to carefully remove the bolts, and ensure the shock is free from any connections.
Once the shock is removed, handle it gently to avoid any damage to the external parts or the internal shock shaft.
Step 3: Disassemble the Shock
Now that the shock is detached, it’s time to begin disassembling it for servicing. Start by removing the air canister from the shock body. This can be done by using a T25 or T30 Torx screwdriver to remove any bolts holding the air canister in place.
Carefully separate the canister from the shock body, ensuring you don’t damage any seals or internal components. If your shock model has additional seals or locking rings, take note of their orientation as you remove them.
Step 4: Drain the Old Oil
With the air canister removed, the next step is to drain the old oil. Place the shock over an oil catch basin or a suitable container to catch the used oil. Hold the shock firmly and allow the old oil to drain completely. This may take a few minutes, depending on the viscosity and amount of oil inside.
While draining, it is essential to inspect the condition of the old oil. If it appears excessively dirty or contains visible debris, it may be a sign that the shock has been neglected or needs a more thorough inspection.
Step 5: Clean the Shock Internals
Once the oil is fully drained, it’s time to clean the internals of the shock. Use a clean cloth or rag to wipe down the shock shaft and any other visible components inside the shock body. Ensure that you remove any residue, dirt, or contaminants that could affect the shock’s performance.
Take care to avoid damaging any internal components, seals, or o-rings during this process. If necessary, use a small brush to gently clean the shock internals.
Step 6: Inspect and Replace Seals and O-Rings
Before refilling the shock with fresh oil, it is important to inspect the seals and o-rings for any signs of wear or damage. Over time, seals can degrade, leading to air or oil leakage and compromised performance. If any seals appear damaged or worn out, replace them with new ones from the shock’s rebuild kit.
Install the new seals carefully, ensuring they fit snugly into their respective grooves and that there are no gaps. Pay attention to the orientation of each seal, as incorrect installation can lead to poor shock performance or damage.
Step 7: Reassemble the Shock
Once the seals and o-rings are replaced, it’s time to reassemble the shock. Begin by reattaching the air canister to the shock body. Carefully align it with the shock’s housing and secure it with the appropriate bolts, using a T25 or T30 Torx screwdriver. Be sure to tighten all bolts to the correct torque specifications as indicated by the manufacturer.
After reattaching the air canister, check the shock for any signs of misalignment or irregularity.
Step 8: Refill the Shock with Fresh Oil
Now that the shock is reassembled, it’s time to refill it with fresh oil. Use the appropriate suspension fluid specified by Fast Suspension for the Fenix COIL model. Using a small plastic funnel, carefully pour the new oil into the shock body, ensuring you add the correct amount based on the manufacturer’s guidelines.
It is essential to use the correct type of oil to ensure proper damping performance. Check the shock’s manual for the correct weight and type of oil.
Step 9: Bleed the Shock
Once the shock is filled with fresh oil, it’s time to bleed the shock. This process involves removing any air bubbles that may be trapped inside the shock, which can affect its performance. Some models have a dedicated bleed valve for this purpose, while others require manual manipulation of the shock shaft.
To bleed the shock, gently compress the shock shaft and work it through its full range of motion several times. This helps dislodge any trapped air and ensures that the oil circulates properly inside the shock.
Step 10: Reinstall the Shock on the Bike
With the oil change complete and the shock properly bled, it’s time to reinstall the shock back onto the bike. Carefully align the shock with the mounting points on the frame and reattach the mounting bolts. Tighten the bolts to the manufacturer’s recommended torque specifications to ensure a secure fit.
Once the shock is in place, check its alignment and ensure it moves smoothly through its range of motion. If everything appears in order, you’re ready to move on to the final steps.
Step 11: Test the Shock
Before heading out on a ride, it’s essential to test the shock to ensure everything is functioning correctly. Start by setting the air pressure to the recommended level, using a shock pump. Carefully cycle the shock through its travel to ensure it moves smoothly and without any unusual resistance or noise.
If you notice any issues, such as a harsh feeling or abnormal noise, recheck the oil level and bleed the shock again. If the problem persists, you may need to disassemble the shock again to address the issue.
Step 12: Fine-Tune the Suspension Settings
Once the shock is fully operational, take some time to fine-tune your suspension settings. This includes adjusting the air pressure to match your riding style, terrain, and rider weight. You may also need to adjust rebound and compression settings to optimize the shock’s performance.
Test ride the bike and make any necessary adjustments to the suspension settings to ensure a smooth, controlled ride. Fine-tuning your shock can make a significant difference in comfort and performance, so take the time to dial it in correctly.
Troubleshooting Common Issues
- Leakage of Oil or Air: If you notice oil or air leaking from the shock, it could indicate that a seal or o-ring is damaged. Inspect and replace seals as necessary.
- Uneven Shock Performance: If one side of the shock feels stiffer than the other, the oil may not have been properly distributed. Ensure the shock was bled correctly and that the oil level is sufficient.
- No Rebound or Compression Damping: If the shock feels too stiff or soft during use, you may need to adjust the oil level or check for air bubbles. Bleeding the shock again could help resolve this issue.
By following these steps, you can maintain and optimize the performance of your Fenix COIL rear shock, ensuring a smooth and responsive ride on every trail. Regular oil changes and proper maintenance will keep your shock performing at its best and extend its lifespan.