How to Service Your Tune Shock SK18 Rear Shock Without a Mechanic

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The Tune Shock SK18 [paid link] is a high-performance rear shock that offers riders a smooth and responsive ride, whether they’re tackling rugged [paid link] trails or going for a long endurance ride. However, like all bike components, the Tune Shock SK18 [paid link] requires regular maintenance to ensure it operates at peak [paid link] performance. Servicing the shock yourself can save time and money, and with the right approach, it’s a manageable task even for riders who aren’t professional mechanics. This guide provides step-by-step instructions for servicing your Tune Shock SK18 rear shock at home, without the need to visit a mechanic.

Tools Required

  • Shock pump
  • 5mm and 6mm hex wrenches
  • Torque wrench [paid link]
  • Small flathead screwdriver
  • Soft cloth or clean rag
  • Suspension grease
  • Isopropyl alcohol
  • Latex gloves
  • Spanner wrench (for removing the shock from the frame)
  • Oil and grease specific to your shock type

Understanding Your Tune Shock SK18

Before jumping into the maintenance steps, it’s important to understand the basic structure and functionality of the Tune Shock SK18. The SK18 is a trunnion-mount shock, meaning it uses a unique mounting system that attaches directly to the frame, making it more compact and offering greater stiffness. This design results in a smoother performance, particularly for long rides on rough terrain.

Like other rear shocks, the SK18 uses air and oil to provide damping and cushioning. The air pressure inside the shock is crucial for tuning the shock’s feel and performance. Over time, the seals within the shock can wear down, and the oil can degrade, reducing the overall performance. This is why servicing is necessary to keep the shock running efficiently.

Step-by-Step Guide to Servicing Your Tune Shock SK18

1. Remove the Shock from the Frame

The first step in servicing the Tune Shock SK18 is to carefully remove the shock from your bike’s frame. To do this:

  • Use a spanner wrench to loosen the trunnion bolts on both ends of the shock.
  • Be sure to hold the shock steady while you loosen the bolts to avoid damaging any components.
  • Once the bolts are removed, carefully slide the shock off the frame and place it on a soft surface.

2. Clean the Shock

Cleaning your shock is an essential step before any service or maintenance work. Use a clean rag to wipe down the entire shock, especially the damper body, the air can, and the mounting hardware. Make sure to remove any dirt, mud, or grime that could affect the performance or interfere with the servicing process.

  • For stubborn dirt, use isopropyl alcohol on a rag to clean the shock body and surrounding areas. This will help to remove oils and sticky substances.
  • Avoid spraying any water directly onto the shock, as this can cause rust or damage to the internal components.

3. Check the Shock for Leaks and Wear

Inspect the shock for any visible signs of wear or leaks. Look at the seals for any cracks or tears. Leaks or damaged seals are often the cause of decreased performance and should be addressed before reassembling the shock. If you find any issues, you may need to replace the seals.

4. Refill or Replace the Oil

Over time, the oil inside the shock will degrade, reducing its performance. Replacing the oil or topping it up is an important part of the maintenance process.

  • Start by removing the air can from the shock. This is typically done by unscrewing the top cap with a 5mm hex wrench.
  • Once the air can is off, use a small flathead screwdriver to remove the oil reservoir screw.
  • Drain any old oil from the shock, allowing it to fully drain into a container.
  • Refill the shock with fresh suspension oil, making sure to use the oil recommended by the manufacturer. Typically, a suspension oil with the correct viscosity for your riding style is required.
  • After refilling the oil, replace the reservoir screw and carefully tighten it to the manufacturer’s specified torque setting using a torque wrench [paid link].

5. Adjust the Air Pressure

Adjusting the air pressure in your Tune Shock SK18 is essential for achieving the desired ride feel. Use a shock pump to adjust the air pressure according to your body weight and riding style.

  • Check the recommended pressure range in the user manual or on the shock’s label.
  • Add or release air using the shock pump, ensuring that the pressure is evenly distributed across both chambers (if applicable).
  • Once the air pressure is adjusted, replace the air valve cap to prevent any dirt from entering the valve.

6. Lubricate the Seals

Lubricating the seals with suspension grease is crucial to ensure smooth performance and prevent wear. Apply a small amount of suspension grease to the shock’s seals and wiper seals.

  • Make sure to use grease that is specifically designed for suspension systems, as regular bike grease may damage the seals.
  • Work the grease gently into the seals, ensuring full coverage but not over-applying it.

7. Reassemble and Reinstall the Shock

Once the oil has been replaced, air pressure adjusted, and seals lubricated, you can reassemble the shock.

  • Slide the air can back onto the shock body.
  • Tighten the top cap and the oil reservoir screw, making sure to follow the recommended torque settings.
  • Reinstall the shock back into the frame, using a spanner wrench to tighten the trunnion bolts securely.

8. Test the Shock

After reassembling the shock and reinstalling it on the bike, it’s important to test it to ensure it’s functioning properly. Sit on your bike and compress the shock several times to check for any abnormal sounds or issues.

  • Test the suspension by riding on a smooth surface first, and then try some rougher terrain to evaluate its performance.
  • Adjust the air pressure if needed to achieve the desired firmness or softness.

Common Troubleshooting Issues

While maintaining your Tune Shock SK18, there are a few common issues that may arise:

  • Shock feels too soft or too firm: This could be due to incorrect air pressure or degraded oil. Make sure to check the air pressure and replace the oil if necessary.
  • Leaking shock: If you notice oil leaking from the shock or air can, inspect the seals for damage. If you find any cracks or tears, replace the seals.
  • Suspension not responsive enough: This could indicate that the oil inside the shock has degraded or the damper is not functioning correctly. Performing an oil change should resolve this issue.

Customization and Optimization for Performance

To optimize your Tune Shock SK18 for your specific riding style, consider these tuning adjustments:

  • Air Pressure: Adjust the air pressure based on your weight and riding style. Higher pressures work well for aggressive riders, while lower pressures provide more comfort and compliance.
  • Rebound and Compression Settings: Fine-tune the rebound and compression settings on your shock for better handling. Adjust these settings to suit the terrain you ride on most frequently.
  • Maintenance Frequency: Regular maintenance is key to long-term performance. Schedule oil changes and seal inspections every 12-18 months, depending on your riding conditions.

Conclusion

Servicing your Tune Shock SK18 rear shock on your own is a highly rewarding task that can greatly extend the life of your shock and enhance your riding experience. By following the steps outlined in this guide, you can ensure that your shock remains in excellent working condition, providing the smooth and responsive ride that the Tune Shock SK18 is known for. Whether you’re replacing oil, adjusting air pressure, or lubricating seals, performing regular maintenance helps optimize performance and prevent costly repairs down the line.