Fox 36 Performance Lower Leg Service Guide

Mastering Your Fox 36 Performance: A Comprehensive Lower Leg Service

The Fox 36 Performance is a renowned fork for its robust performance and reliability on the trails. However, like any high-performance component, it requires regular maintenance to ensure it continues to deliver that plush, controlled ride you expect. A crucial part of this is the lower leg service, a process that replenishes crucial lubrication and ensures seals are in top condition. This guide will walk you through the essential steps to perform a Fox 36 Performance lower leg service, bringing your fork back to its optimal working order.

Why Service Your Lower Legs?

The lower legs of your Fox 36 Performance fork house the air spring and damper mechanisms, as well as the crucial seals and foam rings. These foam rings are designed to hold a small amount of lubricating oil, which constantly feeds the stanchions and seals, reducing friction and wear. Over time, this oil degrades, evaporates, or gets contaminated with dirt and grit. Worn seals can also allow contaminants in, leading to increased stiction, reduced small-bump sensitivity, and premature wear of internal components. Regular lower leg servicing ensures that these vital parts are clean, lubricated, and functioning correctly, prolonging the life of your fork and maintaining its desired performance characteristics.

Essential Tools for the Job

Undertaking a lower leg service requires a specific set of tools to ensure the job is done correctly and without damaging your fork. While some standard bicycle tools will suffice, others are quite specialised. Here's what you'll likely need:

• Bench Mount Work Stand: Essential for holding the fork securely while you work.
• Bike Cleaner: A good quality degreaser or bike wash solution (e.g., Muc-Off Bike Cleaner).
• Pressurised Spray Bottle: For effective application of the cleaner.
• Hose or Pressure Washer: For rinsing the fork thoroughly.
• Clean Rags or Microfibre Cloths: For drying and wiping components.
• 2mm Hex Key: For removing the rebound adjuster set screw.
• 10mm Socket: For the damper-side bottom nut.
• 15mm Socket: For the air spring-side bottom nut.
• Mallet: For gently tapping components loose.
• Long Tyre Lever: Useful for prying out seals and foam rings.
• Pick Tool: For manipulating small parts like foam rings.
• Syringe: For accurate measurement and refilling of suspension oil.
• Torque Wrench: For precise tightening of the bottom nuts.
• Boost Thru-Axle (Optional but Recommended): To brace the lower legs during disassembly.
• Fox 36 Seal Driver Tool (Recommended): For correctly installing new seals.
• Plastic Container: For pre-soaking foam rings.

Fox 36 Performance Lower Leg Service Specifications

Adhering to the correct specifications is vital for the longevity and performance of your fork. Here are the key quantities and types of fluids for the Fox 36 Performance:

Step-by-Step Lower Leg Service Procedure

Step 1: Thorough Cleaning

Before you begin any disassembly, a meticulous cleaning of the fork is paramount. Dirt and grit can easily ingress into the fork's internals if not properly removed. Spray the entire fork liberally with your chosen bike cleaner. Allow it to sit for a minute or two to break down grime, then rinse thoroughly. A pressure washer or hose is effective, but pay attention to cleaning around the seals and stanchions. Ensure the fork is completely dry before proceeding.

Step 2: Removing the Rebound Adjuster

On the damper side (typically the right leg from the rider's perspective), locate the rebound adjuster knob. This is usually protected by a small cap. Gently pry off this cap. Once exposed, you'll see a small set screw. Using your 2mm hex key, loosen this set screw. Be careful not to overtighten or strip it. With the set screw loosened, the rebound adjuster knob should be removable.

Step 3: Detaching Bottom Nuts and Crush Washers

Now, you need to unfasten the bottom nuts that secure the lower legs. On the damper side (right leg), use a 10mm socket to remove the bottom nut. On the air spring side (left leg), use a 15mm socket to remove its bottom nut. You'll notice crush washers on each of these bolts. These are single-use items, and if you intend to reuse them, mark their orientation. However, it's generally recommended to replace them with new ones during a service.

Step 4: Separating Damper and Air Spring

The damper and air spring shafts are often held in place within the lower legs by a bit of stiction. To break this seal, you'll need to apply a sharp, upward force. Fox provides specific tools for this, but you can often use the sockets you removed the bottom nuts with. Place the socket onto the end of the shaft, ensuring a good fit. With a gap of about 5mm between the fork leg and the socket, give it a firm tap with a mallet. This should shock the components loose. Repeat this process for both the damper and air spring sides.

Step 5: Lower Leg Removal and Oil Drainage

With the bottom nuts removed and the shafts loosened, you can now separate the lower legs from the upper stanchions. Carefully rotate the fork so the legs are pointing upwards. The damper and air spring shafts will slide out of the lower legs. Have your oil drain pan ready, as there will be residual oil within the fork legs. The lower legs are now free, with only the fork brace holding them in place. For added stability during this stage, consider installing a Boost thru-axle through the dropouts.

Step 6: Replacing Foam Rings and Seals

This is a key part of the lower leg service. You'll need to remove the old foam rings and dust seals. Using a long tyre lever or a pick tool, carefully pry out the old seals and foam rings from the bottom of the stanchions. Once removed, take your new foam rings and pre-soak them in a container filled with Fox 20 WT Gold suspension fluid. While the foam rings are soaking, you can clean the interior surfaces of the lower legs. With the lower legs clean, carefully insert the pre-soaked foam rings into their correct positions using a pick tool. Next, apply a thin layer of silicone grease (like Renolit SL 410 M) to the inside of the new dust seals to aid installation. Using a Fox 36 seal driver tool, carefully and evenly tap the new seals into place until they are fully seated.

Step 7: Reinstalling Damper and Air Spring

Before reinserting the damper and air spring shafts, ensure you've placed the sag o-ring onto the air spring shaft if it's a Float air spring. Apply a thin layer of silicone grease to the inside of the newly installed seals. This will help the shafts slide in smoothly and prevent damage. Carefully align the damper and air spring shafts with their respective lower legs and guide them into place. It might require some gentle wiggling and back-and-forth motion for them to seat correctly. Ensure the damper (with the rebound adjuster) goes into the right leg, and the air spring into the left.

Step 8: Refilling with Suspension Oil

With the damper and air spring reinstalled, it's time to add the fresh suspension oil. Rotate the fork so the lower legs are pointing upwards to allow gravity to assist the oil flow. Ensure the damper and air spring shafts are extended slightly to create space for the oil to enter. Using a syringe, carefully measure and add 40 ml of Fox 20 WT Gold suspension fluid into the damper side (right leg). Then, add 10 ml of Fox PTFE Infused 5WT suspension fluid into the air spring side (left leg).

Step 9: Tightening Bottom Nuts and Final Assembly

Once the oil has been added, you need to reattach the bottom nuts. Fit new crush washers onto the damper and air spring bolts. The damper side requires a 13mm crush washer, and the air spring side uses an 8mm crush washer. Screw the bottom nuts back into place. Using your torque wrench, tighten both nuts to the specified torque of 7.4 Nm. Finally, reattach the rebound adjuster knob by tightening its set screw with the 2mm hex key, and then replace the protective cap. A final wipe-down with a bike protectant spray will leave your fork looking and feeling fresh.

Frequently Asked Questions

Q1: How often should I service the lower legs of my Fox 36 Performance fork?

A: For optimal performance and longevity, it's recommended to perform a lower leg service every 50-100 riding hours, or at least once a year, depending on your riding conditions and frequency.

Q2: Can I use different suspension fluids?

A: It's strongly advised to use the specific fluids recommended by Fox. Using incorrect fluids can lead to poor performance, seal damage, and void your warranty.

Q3: What if I don't have a seal driver tool?

A: While a seal driver tool ensures even and correct installation, you can attempt to carefully tap the seals in with a socket of the correct size, ensuring they go in straight and are not damaged.

Q4: My fork feels sticky after the service. What could be wrong?

A: This could be due to improperly installed seals, insufficient lubrication, or dirt still present in the system. Double-check the seal installation and ensure all components were clean before reassembly.

Q5: Do I need to service the air spring side separately?

A: Yes, while this guide covers the lower leg service which includes the air spring side, a full fork service would also involve servicing the air spring internals (air canister) periodically.

By following these steps, you can confidently perform a lower leg service on your Fox 36 Performance fork, ensuring it remains a capable and enjoyable component for all your adventures.

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