FOX OPEN BATH FORK - BASIC OVERHAUL GUIDE
(Referencing a 2008 Specialized Stumpjumper FSR Expert 26" with F120 RLC)
This is how I disassembled, inspected, cleaned, and reassembled my F-Series forks. This guide will likely work for most older Fox forks as well since they seem to have only minor differences. The key difference being the amount of fork oil required which can be found here, then going down to the Fork - Basic Maintenance heading, and selecting 2002-2013 Bath Oil Chart. Do not substitute an incorrect oil and note that some oil requirements have been updated.
This is the first oil change on my forks that are ten years old (currently Oct 2018). I was riding two days a week for about a year or two before riding my Allez road bike almost exclusively. I could not find any leaks and the wiper seals looked fine, but had noticed on my first outing in over a year that the first few millimeters of fork travel were somewhat loose. I had very successfully replaced a blown Brain-assisted shock two years ago with a RockShox Monarch RT3 (7.25" x 1.25"), so this was no big surprise. The surprise came with the price of a comparable fork (RockShox Reba) ...so I opted to rebuild. During my overhaul, I found that I only needed to replace the fork oil, the Float Fluid, and the two crush washers at the bottom of the fork legs (this is the minimum you will need). If you buy the Fox 32mm Open Bath kit (80300078), you will get the crush washers and Float Fluid along with any o-rings that may have gone bad or been damaged. This kit works for a lot of the 32mm Open Bath forks, so there will be extra parts. You may also want to order a wiper seal kit with new sponge foam rings just in case. You will certainly need the correct color/weight of Fox Suspension Fluid. Some Slick Honey or SRAM Butter is recommended for lubing o-rings, but I used a water-proof grease I always have on hand.
On the tube portion's (the gold uppers) Damper side, set the red Rebound Adjuster to halfway and set the blue Lockout Lever to full lock (clockwise). You may want to mark the final orientation of the lever on the triple tree, but it is not necessary as I will explain how to reset it later. Use one hand to secure the Rebound Adjuster from moving, then use the other hand to turn an allen wrench and loosen the screw securing it to the fork. Set the screw and adjuster aside. Loosen the three tiny grub screws securing the Lockout Lever - they do not need be removed, just loosened enough to lift the lever off since they push bearings into a recess to grab onto the Damper Assembly (see second pic below). Lift off the Compression Dial, being mindful of the detent bearing underneath it and the dial's orientation. Clean any grit and grime off of these small components and set them aside.
On the Spring side, twist off the blue Air Valve Cap to expose the Schrader valve. Flip the fork over and examine how the Spring Assembly is secured inside the fork. There is an internal ring clip that has a "lip" to it for a small flathead screwdriver to grab: slide the ring's lip inward, then prying it up slightly while working around the perimeter until it lifts out completely. There is a black, cylindrical bushing that is below the ring clip which will now come out easily. Note the orientation (up versus down) and set both parts aside. You can now remove the entire Spring Assembly out through the bottom of the tube. Using a 26mm socket, carefully loosen both fork tube tops so that the socket does not slip off. The Air Valve and Damper Assemblies will both come out the top. Remove the Schrader Valve from the Air Valve Cap, clean the backside of the Air Valve Cap (see second pic below), and set all aside. Compress the Damper several dozen times over a collection bin until all the old oil is evacuated - you may need to invert the Damper to facilitate this. Clean the excess oil off of these assemblies and set aside.
Flip the forks upside down and secure in a stand or a padded vice. You can pour new oil into the tubes like this, or reinstall the legs and then add the oil. I added the oil first. Using a syringe, I added 30cc of Red 10wt oil to the Spring side. Then I used a Ratio Rite to pour 160cc of oil into the Damper side. I smeared a light film of the oil onto the inside of the wiper seals and carefully slid the fork leg assembly onto the tubes. Standing on a stool, I looked down to make sure the internals were lined up with their lower fork leg holes and finished sliding the unit together. Place the new crush washers over the threads and reinstall the nuts on the bottom of the fork legs. Tighten the nuts with a 10mm socket just enough so oil will not seap out. Place the unit on the table and torque each nut to 40 inch pounds and then 50 inch pounds. Wipe up any excess oil on the forks. Reinstall the blue Blowoff Control knob on the bottom of the Damper side and add 60psi to the Spring side via the Air Valve. Compress the forks a few times to ensure a smooth stroke.
On the Damper side, reinstall the blue Compression Dial - do not forget to grease and install the detent bearing underneath. Now place the Lockout Lever (do not grease this) on top, aligned with your mark. If you didn't mark this, you can set it by using the lever to rotate the mechanism all the way clockwise, then placing the lever so it is just shy of hitting the backside of the triple tree - this will allow you to throw the Lockout to its max. Now, turn all three grub screws in a little to secure it - do not tighten them all the way down as it will cause too much friction with the Compression Dial. Test the Lockout - if it is not fully locking the fork from compressing, you may simply need to turn the Blowout Control to max and retest. Reinstall the red Rebound Adjuster and secure it with the screw without changing the setting. If you tighten the screw, but don't hold the adjuster, it could "lock" itself to fully open - if it doesn't click into the rebound detents easily, do not force it! You will have to remove the adjuster and use pliers to un-stick it (this may also happen in the other direction when you are taking the screw out).
Clean the fork races and reapply grease to the head bearings. Reinstall the fork assembly, handlebar, front tire, and caliper. To center and align the caliper on the rotor, turn the two caliper bolt assemblies down until they just barely make contact (it has to be able to shift around a bit), spin the front tire, and apply the brake. Carefully snug the caliper bolts a little. Repeat and then tighten the caliper bolts down. Done.
CrankyGypsy (established 2001)