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40 R


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

Disassembly

Remove the 40 Damper Topcap

  1. Unscrew—but do not remove—the damper topcap with a 32 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.

     
  2. Leave the topcap assembly on. Secure your fork so that the fluid inside of the fork does not spill out.

Remove the 40 R Damper

  1. Remove the black protective cap from the bottom of the right fork leg.

  2. Using a 15 mm socket, remove the bottom nut.

  3. Screw the bottom nut back on two full turns.

  4. Using a plastic faced hammer with the 15 mm socket, gently strike the bottom nut to release the damper assembly.

  5. Holding the fork over an oil pan, remove the bottom nut. 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.

  6. Turn the fork right-side up and then remove the topcap.

    Note:  You do not need to remove your lower leg assembly at this point.


  7. Pull up on the topcap and remove the 40 Damper assembly.

Remove the 40 Spring Topcap

Note:  Before removing the preload topcap, turn the preload knob fully counter-clockwise. This releases the load on the coil spring, and makes it less likely that the spring will pop out when the topcap is removed.

CAUTION:  There is a small amount of suspension fluid in the left leg. Screw in the topcap at least 2 full turns before turning the fork upside-down to prevent the fluid from spilling out.

Unscrew the preload topcap with a 32 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.

 

Remove the 40 Spring

  1. You can now fully unthread the topcap to expose the coil spring.

  2. Pull out the coil spring. Depending on the travel setting of the fork, there may be up to 4 travel spacers (see picture below left) on top of the coil spring. These can be removed and set aside.

     
  3. Sometimes the plunger shaft will come out when the coil spring is pulled out. If that is not the case, turn the fork upside-down and allow the plunger shaft to drop out. Depending on the travel setting of the fork, there may be up to 4 travel spacers (see picture below left) on the plunger shaft. They do not need to be removed unless the travel on the 40 is being changed.

     

Remove the 40 Lower Assembly

  1. Making sure the fork is secured in a bike stand or 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.

Remove the Thru-axle

  1. Loosen the four hex bolts on the lower legs using a 5 mm hex key. They do not need to be removed.

  2. Using a 5 mm hex key, unscrew the thru-axle from the right side (rider's perspective) of the lower legs.

  3. Slide the thru-axle out from the lower legs.

Remove the Dust Wipers from the Lower Assembly

  1. Using an open-end wrench, pry up the dust wipers. Be careful not to scratch the ID 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 case, the anodizing on the upper tubes should be examined. If the anodizing has worn off due to insufficient lubrication, replacement of the crown/steerer/upper tube assembly is imminent.

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

    FOX 40 Dust Wiper Kit (FOX PN: 803-00-125)
    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.

Replacing the Dust Wipers

Note:  The photos in this section, while adequately serving to demonstrate this service procedure, are not of the 40 fork model.

Discard the original dust wipers and foam rings, and install new ones from the FOX 40 mm dust wiper kit (PN 803-00-125).

  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.

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

FIT Damper Service

Disassembly

CAUTION:  Wear safety glasses during this entire procedure.

Note:  Ensure that the rebound adjuster knob is fully turned counterclockwise (OUT).

  1. 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.

     
  2. 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.

  3. Try to grip the bladder cap with you finger and work the cap up and off the stud. Some times 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.

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

     
  5. 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.

     
  6. Clamp damper cartridge body into the soft jaw vise using correct size clamp holes on shaft clamp PN 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.

  7. Before you unthread the seal head, open it over your oil drain pan since 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.

  8. Inspect the rebound piston and the piston glide ring (pink Z cut) PN 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

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

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

  2. 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.

  3. 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).

  4. Slowly pour FOX suspension oil into the cartridge body bladder end, cycling slowly the damper shaft (hold onto topcap). Refer to the Oil Volumes table for suspension oil weight and amount specifications per fork year and model.

    This action 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.


     
  5. Pull 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.

      
  6. Let the cartridge sit for about 30 minutes to allow all the air to escape out of the oil.
  7. Inspect bladder and cap for cuts, nicks, and burrs (replace as needed with bladder PN 210-22-106 and cap PN 210-22-105). Make sure to remove all burrs from bladder cap.

  8. 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 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.

     

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

  10. 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.

     
  11. 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.

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

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

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

  15. Tighten the seal head slightly, but do not tighten it down completely yet. When tightening the seal head, be careful not to pinch the seal head o-ring.

  16. 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 #19.

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

     
  18. 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 tighten it down yet. When tightening the seal head, be careful not to pinch the seal head o-ring. Perform step #16 through step #18 again.

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

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

Assembly

Install the 40 R 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 15 mm socket, tighten the bottom nut to 50 in-lb (5.65 N-m) torque.

  4. Refer to the Oil Volumes table for suspension oil weight and amount specifications per fork year and model. Pour in the proper amount of FOX suspension oil into the right upper tube.

    Note:  Although the damper is not shown in the picture below, it should already be in the upper tube.


  5. Screw the damper topcap into the upper tube with a 32 mm 6-point socket and tighten it to 220 in-lb (24.86 N-m) torque.

Install the 40 Damper Topcap

  1. Tighten the topcap to 220 in-lb (24.86 N-m) torque with a 32 mm 6-point socket. Be careful not to slip and damage the wrench flats.

  2. If the rebound knob was removed, place the rebound knob back 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 40 Spring

  1. Determine the desired 40 travel setting. Travel is determined by the amount of spacers either on top of the coil spring and/or attached to the spring plunger shaft.

     
    40 Travel Spacer Settings:

    Travel Setting

    # of Spacers Under Topcap

    # of Spacers on Plunger Shaft

    8.0" (203 mm)

    4

    0

    7.5" (190 mm)

    3

    1

    7.0" (178 mm)

    2

    2

    6.5" (165 mm)

    1

    3

    6.0" (152 mm)

    0

    4

  2. Drop the spring plunger shaft into the left upper tube. If you want the 40 at its longest travel setting (8.0", or 203 mm), there shouldn't be any travel spacers on the plunger shaft. Otherwise, there should be a maximum of four spacers.

  3. Drop the coil spring into the upper tube. If you want the 40 at its shortest travel setting (6.0", or 152 mm), there shouldn't be any travel spacers on top of the coil spring. Otherwise, there should be a maximum of four spacers, which can be dropped on top of the coil spring.

     
  4. Push down on the lower leg assembly and guide the spring plunger shaft through the bottom of the lower leg hole. Place a new crush washer on the shaft.

     
  5. Screw the bottom nut on the shaft and tighten the bottom nut to 50 in-lb (5.65 N-m) torque with a 10 mm socket and torque wrench.

     
  6. Turn the fork upside-down and pour FOX suspension oil into the spring-side lower leg hole. Refer to the Oil Volumes table for suspension oil weight and amount specifications per fork year and model.

  7. Screw on the preload topcap assembly until you can no longer see the topcap o-ring. You will tighten it down later.

Install the 40 Preload Topcap

  1. Tighten the topcap to 220 in-lb (24.86 N-m) torque with a 32 mm 6-point socket. Be careful not to slip and damage the wrench flats.

      
  2. Adjust preload on the fork in accordance with the fork's owner's manual. The table below shows the proper sag settings for the 40.

    40 SAG SETUP

    Travel

    15 - 25% Sag

    6 in. (152mm)

    0.9 - 1.5 in. (23 - 38 mm)

    6.5 in. (165 mm)

    1.0 - 1.6 in. (25 - 41 mm)

    7 in. (178mm)

    1.1 - 1.8 in. (27 - 45 mm)

    7.5 in. (191mm)

    1.1 - 1.9 in. (29 - 48 mm)

    8 in. (203mm)

    1.2 - 2.0 in. (30 - 51 mm)


use proper tools, supplies & kits · read all warnings · know oil volumes and inspection guidelines · know disc brake specifics for all Fox forks · know air shaft travel specifics for FLOAT and F-Series forks · use correct fork torque specifications