36/40 FIT Cartridge Service

Disassembly

CAUTION: Wear safety glasses during this entire procedure.

Note: Ensure that the rebound adjuster knob is turned fully counterclockwise (OUT) and [RC2 ONLY] the high- and low-speed compression adjusters are also turned full counterclockwise.

At the bottom end of the cartridge, remove the 18 mm bladder cap lock nut. Use a 8 mm box end wrench to hold the compression adjuster shaft feature tight as you unthread the 18 mm nut. The 18 mm nut may be tight, as blue Loctite is used at the factory during installation. Set the nut aside on clean shop towel. You may need to remove some of the hardened Loctite.

Place a shop towel over the bottom stud bladder end and compress the damper shaft all the way in towards the seal head. This will displace the oil and apply pressure on the bladder and cap. This action will help to pop the bladder and cap up, or even out of the cartridge body.

Try to grip the bladder cap with you finger and work the cap up and off the stud. Sometimes you will need to gently grip the cap with channel lock pliers to grip and tug the part off; a little wiggle action as you pull also helps.

Occasionally, the bladder cap will dislodge from the bladder. Simply pull the bladder out by pulling it with plastic dental pick.

Pour as much oil out of the system as you can into a drain pan and also cycle the damper shaft a few times this will purge more oil out of the damper.

Clamp the damper cartridge body into the soft jaw vise, using the correct size clamp holes on shaft clamp P/N 803-00-084. Unthread the black seal head using a thin style 14 mm open end wrench.

CAUTION: Do not over-tighten the vise, or damage to the cartridge body will result.

Before you unthread the seal head, open it over your oil drain pan as oil is going to flow out of the cartridge once it is opened. Drain as much oil as you can out of the damper shaft assembly and set it onto clean shop towel.

Inspect the rebound piston and the piston glide ring (pink Z cut) P/N 002-02-011 for excessive wear or damage. Excessive wear on the glide ring may cause a reduction in rebound damping.

Note: In the image below, the bottom out resistance is set to firm. To change the bottom out resistance, rearrange the spacers and glide ring to your resistance preference by holding the rebound piston bolt with an 8 mm open end wrench and unthread the set screw with a 2 mm hex key. As the glide ring increments from the end of the shaft and towards the bottom-out compression system, bottom out resistance decreases. Torque the set screw to 25 in/lbs.

For further detail, see bottom-out control explained.

Assembly

Clamp damper cartridge body into the soft jaw vise using the correct size clamp holes on the shaft clamp. Thread the black seal head with damper shaft back into the cartridge body with 14 mm crow foot and torque wrench torque the seal head to 35 in-lbs.

CAUTION: Do not over-tighten the vise, or damage to the cartridge body will result.

Unclamp damper cartridge and turn it around so that the bladder end of cartridge is up. Re-clamp damper cartridge body into the soft jaw vise using correct size clamp holes on shaft clamp.

CAUTION: Do not over-tighten the vise, or damage to the cartridge body will result.

Pull down top cap toward the floor too fully extend damper shaft.

Note: Before adding oil make sure that the rebound adjuster knob is fully turned counterclockwise (OUT) and the high and low-speed compression adjusters are also turned full counterclockwise.

Slowly pour 10 wt. FOX Suspension Fluid into the cartridge body bladder end, cycling slowly the damper shaft (hold onto topcap). This will draw the oil into the cartridge. Pour more oil in as you cycle the shaft in and out slowly. Make sure to compress the topcap all the way in until it stops; this will purge air out of the hydraulic bottom-out system. Air bubbles will come up through the oil during the filling operation. Slowly cycle damper shaft all the way through full travel about 20 times.

Pull the damper shaft towards the ground to the fully extended position. The oil level in the bladder body should be about 2 inches down from the top. It may be necessary to add or subtract some oil to attain the 2-inch oil level.

Let the cartridge sit for about 30 minutes to allow all the air to escape out of the oil.

Inspect bladder and cap for cuts, nicks, and burrs (replace as needed with bladder P/N 210-22-106 and cap P/N 210-22-105). Be sure to remove all burrs from bladder cap.

Lightly grease the outer edges as well as the inside edges of the sealing lips of the bladder. Install the inner sealing lip of the bladder onto the inner seal groove of the bladder cap, and carefully spin the bladder to make sure it is fully engaged. Push from the top of the bladder (so that it is not compressed inward) and slowly roll the outer sealing lip of the bladder onto the bladder cap.

Grip the outside diameter of the top edge of the bladder. Push it outward to ensure you have maximum air volume inside the bladder.

Double-check and make sure that the damper shaft is pulled to the fully extended position and wrap a shop towel around the outside of the cartridge body top area. This will soak up excess oil, as it is purged during the bladder insertion process.

Install the bladder cap assembly into the oil-filled cartridge by slowly pushing it down into the cartridge body bladder cavity. Make sure to push it down all the way. The bladder cap should end up flush too the top of the cartridge body bladder cavity. You can use a socket (e.g., 15 mm) large enough to fit over the damper shaft adjuster rod to push down on the bladder cap assembly.

Clean off excess oil from cartridge stud threads using cotton tip swaps and isopropyl alcohol, and blow or compressed air dry after cleaning.

Add three drops of Loctite (Blue – Medium) to the threaded stud above the bladder cap's top edge.

Thread the bladder cap nut back onto the cartridge stud. Hold onto the 8 mm hex with a wrench.

Holding the adjuster shaft with a 8 mm closed end wrench, torque the bladder cap nut to 90 in-lbs. using a 14 mm crow foot open end and torque wrench.

RC2 ONLY: Temporarily put the high and low-speed compression knobs back on the adjuster shaft and turn them fully clockwise (IN). This will be the firmest compression settings on both adjustments.

Tighten the seal head slightly, but do not torque it down yet. When tightening the seal head, be careful not to pinch the seal head O-ring.

Compress the assembly with your hands. You should feel firm resistance to movement and there should be no play. If air has entered the system, you will feel a little bit of play at the top of the compression stroke. The allowable amount of play is 3 mm. If more play is measured, continue with the next step. Otherwise, skip to step #21.

Remove the seal head and top the cartridge body off with oil.

Slide seal head all the way to the piston. Insert the piston and seal head assembly into oil. Tighten the seal head slightly, but do not torque it down yet. When tightening the seal head, be careful not to pinch the seal head O-ring. Perform step #18 again.

Using a 14 mm crow foot open end wrench and torque wrench, torque the seal head to 55 in-lbs.

The damper assembly is ready for installation back into your fork.