F100X/F80X

Note:  Some of these photos, while adequately serving to demonstrate service procedure, may not accurately show the fork model.

Disassembly

The X Topcap does not need to removed to disassemble the topcap assembly. If you do not wish to remove the rebound knob, skip to step #3.

Before removing the X Topcap, you must first remove the retaining nut at the bottom of the fork leg. The retaining nut will be removed in the next step.

Remove the X Topcap

1. With a hex key wrench, remove the hex key on top of the red rebound knob.
   
   
2. Remove the rebound knob by lifting it.
   
   
3. Unscrew—but do not remove—the damper topcap with a 26 mm 6-point socket. Be careful not to slip and damage the wrench flats.

   Tip:   You may opt to grind down the socket as shown below, to improve its meshing with the wrench flats of the topcap.

   
    
4. Leave the topcap assembly on. Secure your fork so that the fluid inside of the fork does not spill out.
   • After loosening the X topcap assembly, you are now ready to remove the bottom nut on the damper, which will allow you to fully remove the X damper assembly from the lower leg assembly.
   • Place an oil pan underneath the fork before loosening the bottom nut.
   • Make sure the topcap assembly is screwed in a few turns since you will need to turn the fork upside-down to access the bottom nut. You will not want suspension fluid spilling all over your new Hush Puppies.

Remove the Lockout Force Threshold Knob

1. With a hex key wrench, loosen—but do not remove—the bolt on the knob at the bottom of the right fork leg.
   
   
2. Once the bolt is loose enough, remove the knob and set it aside.
   
   

Remove the X Damper

1. Using a 10 mm socket, remove the bottom nut.
   
   
2. Screw the bottom nut back on two full turns. Using a plastic faced hammer, gently strike the bottom nut to release the damper assembly.
   
   
3. Holding the fork over an oil pan, remove the bottom nut and crush washer. If the crush washer isn't attached to the nut, check the bottom of the lower leg; it might be stuck there. Suspension fluid should flow out.
   
   
4. Making sure the fork is right-side up, remove the topcap.
   
   
5. Pull up on the topcap and remove the X damper assembly.
   
   

Remove the Air Topcap

1. Remove the aircap.
   
   
2. While holding a rag over the topcap assembly, depress the Schrader valve to release air pressure.
   
   
3. Unscrew—but do not remove—the damper topcap with a 26 mm 6-point socket. Be careful not to slip and damage the wrench flats. You may need to grind down the socket so that it properly grips the wrench flats on the topcap.
   
    
4. Leave the topcap assembly on. Secure your fork so that the fluid inside of the fork does not spill out.
   • After loosening the air topcap, you are now ready to remove the bottom nut on the lower leg, which will allow you to fully remove the air spring assembly from the lower leg.
   • Place an oil pan underneath the fork before loosening the bottom nut.
   • Make sure the air topcap is screwed in a few turns since you will need to turn the fork upside-down for better access to the bottom nut.

Remove the 32 mm Air Spring

1. Using a 10 mm socket, remove the bottom nut. If the washer is not stuck to the bottom of the lower leg, check the inside of the bottom nut and remove it using a dental pick.
   
    
2. Screw the bottom nut back on until it is flush with the end of the air shaft. You should be able to push down on the bottom nut to push up the air shaft plunger.
   
   
3. If you cannot dislodge the damper by pushing down on the bottom nut, dislodge the air shaft by tapping on it with a soft-faced mallet.
   
   
4. Both the damper shaft and air spring shaft should be dislodged from the lower legs.
   
   
5. Remove the air spring from the upper tube.
   
    

Remove the Crown Steerer Assembly

1. Both the damper shaft and air spring shaft should be dislodged from the lower legs, allowing you to remove the lower leg assembly. Drain the lower leg assembly into an oil pan before putting it aside.
   
   
2. Clean the crown steerer tube assembly with parts cleaner.
3. Inspect the assembly for any nicks, cuts, scrapes, scratches or gouges, and replace if necessary.
   • The assemblies that normally prevent the removal of the lower legs should already have been removed.
   • Removal of the lower legs should be done with the fork secured in a bike stand and over an oil pan.

Remove the 32 mm Lower Assembly

1. Making sure the fork is secured in a bike stand or soft-jawed vise and over an oil pan, turn the fork upside-down.
2. Remove the topcap assemblies from both sides of the fork, and let the oil drain out.
   
   
3. If not already done, remove all base valve bolts and knobs.
4. Gently pull up on the lower legs to fully disengage them from the upper tubes.
   
   
5. Drain any remaining fluid from the lower legs into an oil pan.
   • After removal of the lower legs, it is a good idea to replace the dust wipers and foam rings
   • When possible, the bicycle/fork should be stored upside-down to keep the dust wipers and foam rings lubricated.

Remove the Dust Wipers from the Lowers

1. Using an open-end wrench, pry up the dust wipers. Be careful not to scratch the inner surface of the lower legs.
   
   
2. After the dust wipers are removed, the foam rings will be visible. Lift them out of the lower legs. If they cannot be located, check under the dust wipers; they might be stuck underneath them.
   
   

   You can get a general sense of the condition of the fork by examining the foam rings. Dry foam rings indicate a lack of fluids or, possibly, a leak. Dirty foam rings may indicate a faulty dust wiper. In either condition, the anodizing on the upper tubes should be examined. If the anodizing has worn off due to insufficient lubrication, replacement of the crown steerer tube assembly might be necessary.

   After examining the dust wipers and foam rings, they can be discarded and replaced using the following replacement kits:

   FOX 32MM Dust Wiper Kit (FOX P/N: 803-00-079)

   Lower Leg Bushings:

   FOX Racing Shox recommends that you have your bushings serviced at a Factory Authorized Service Center. Refer to http://www.foxracingshox.com/fox_tech_center/service.htm.

   Bottom-out Bumpers:

   • Bottom-out bumpers are technically not a serviceable item, so they rarely need to be replaced.

   Dropouts:

   • Over time the knurled surfaces of the front wheel hub and quick-release skewer wear out the dropout region of the lower leg (see Dropout photo below).
   • Inspect and measure the thickness of the dropouts every 6 months or 100 hours. Ensure that any point on the surface is above the minimum specification of 6.20 mm (see Measure Dropout photo below).
   • Replace the lower leg assembly if the dropout thickness is at the minimum specification or less.

     Dropout

     Measure Dropout

Replacing the Dust Wipers

Discard the original dust wipers and foam rings, and install new ones from the FOX 32 mm dust wiper kit (PN 803-00-079).

1. Presoak the new foam rings in damper oil.
   
   
2. Place the oil-soaked foam rings in the lower legs as shown.
   
   
3. Install the new dust wipers over the foam rings and seat them fully into place using thumb pressure, as shown. You can apply a thin coat of oil to the sides of the dust wipers, to ease their installation.
   
   

Note:  be sure to seat the dust wipers into the lower assembly completely and evenly.

Damper Cartridge Service

Specific service instructions for internal assemblies are in the works. In the meantime, the fork has been broken down into its main parts, and can be further examined. Replace any main sub-assemblies as required.

Note:  Before proceeding from this point, be sure that you have drained all oil from the damper cartridge.

Go to Damper Cartridge Oil Removal for more information about this procedure.

Installing the 32 mm Air Spring and Lower Assembly

1. Grease the threads on the upper tube.
   
   
2. Drop the air spring into the upper tube.
   
     
3. While tilting and gently pressing the upper tubes into the lower leg assembly, push past the newly installed dust wipers and foam rings, sliding the lower leg assembly onto the crown steerer assembly part way.

   Tip:   slightly stretching the outer lip of the dust wipers in this step won't risk damaging them.

4. Turn the fork upside-down and pour the proper amount of FOX suspension oil through the hole in the bottom of the lower leg. Consult the Oil Volumes table for suspension oil weight and amount specifications per fork year and model.
   
   
5. Push the air shaft down until it protrudes from the bottom of the lower leg. Place a new crush washer on the shaft, then screw the bottom nut onto the shaft. Or, you can place the washer on the bottom nut and screw them on together.
   
    
6. Tighten the bottom nut to 50 in-lb (5.65 N-m) torque with a 10 mm socket and torque wrench.
   
   
7. Turn the fork right-side up and place 5 cc of FLOAT Fluid (one pillow pack) into the left upper tube.
   
   

Install the Air Topcap

1. Tighten the damper topcap to 220 in-lb (24.86 N-m) torque with a 26 mm 6-point socket. Be careful not to slip and damage the wrench flats.
   
    
2. Remove the air topcap.
   
   
3. Using a FOX High Pressure Pump, inflate the spring-side topcap Schrader valve to between 45 - 125 psi (3.10 - 8.62 bar), depending on rider weight. Consult the table below for air pressure guidelines.

   CAUTION:  Never exceed 200 psi (13.79 bar).
   
   

   AIR SPRING SETTING guidelines
   Rider Weight	Air Pressure
   < 125 lbs.	45 psi
   125 - 135 lbs.	50 psi
   135 - 145 lbs.	55 psi
   145 - 155 lbs.	65 psi
   155 - 170 lbs.	75 psi
   170 - 185 lbs.	85 psi
   185 - 200 lbs.	95 psi
   200 - 215 lbs.	105 psi
   215 - 230 lbs.	115 psi
   230 - 250 lbs.	125 psi

   

4. Screw on the air topcap.
   
   

Install the X Damper

1. Insert the damper assembly into the right upper tube. Make sure the damper shaft protrudes from the bottom of the lower leg.
   
   
2. Place a new crush washer on the end of the damper shaft.
   
   
3. Screw on the bottom nut. Using a torque wrench and 10 mm socket, tighten the bottom nut to 50 in-lb (5.65 N-m) torque.
   
   
4. Turn the fork right-side up and pull up on the topcap assembly. Consult the Oil Volumes table and per the model and year of your fork, pour in the proper amount of FOX suspension oil into the right upper tube.
   
   
5. Screw the topcap assembly on and tighten to 220 in-lb (24.86 N-m) torque with a 26 mm socket and torque wrench.
   
   

Install the X Topcap

1. Screw the damper topcap into the upper tube with a 26 mm 6-point socket.
   
   
2. Place the rebound knob on the topcap assembly. The lever and adjuster shaft are indexed.
   
   
3. Using a 1.3 mm (0.050") hex key wrench, tighten the hex key on top of the rebound knob.
   
   

Install the Lockout Force Threshold Knob

1. Place the knob on to the adjuster shaft. Align the hex nut on the knob with the divot on the end of the adjuster shaft.
   
   
2. Using a 1.5 mm hex key wrench, tighten the hex nut.
   
   

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FOX Factory Inc.