SERVICE PROCEDURES
2021-2025 DHX2 Rebuild
Required Parts
- 025-03-063 Oil: Suspension Fluid, 4 WT, 1.0 Liter Bottle
- 803-01-488 Seal Kit: 2021 DHX2 Damper Rebuild
Required Tools
- 398-00-280 Tooling: Eyelet Torque Tool
- 398-00-881 Tooling: Custom Spanner Socket, 4-Pin, 2021 DHX2 / FX2, Comp Base Valve
- 398-00-882 Tooling: Custom Spanner Socket, 4-Pin, 2021 DHX2 / FX2, Reb Base Valve
- 398-00-951 Tooling: Torque Fixture, 54mm Trunnion Eyelet, Tall
- 803-00-463 Kit: Fill Machine Adapter, 04-07 Epic IV, DHX Air, RC2_RC4 Shocks
- 803-00-566 Kit:Bike IFP Depth Setting Tool Set
- 803-01-545 Kit: Tooling: Clamps, 2021 DHX2 / Float X2, Rezi Body
- 803-01-578 Kit: Service Tool, 2021 DHX2 / Float X2, VVC Set, Assembly
- 803-01-826 Kit: Tooling: Rear Shock, Rezi End, Air Fill Adaptor, MY 2021
WARNING: Always wear safety glasses and protective gloves during service to prevent potential injury. Failure to wear protective equipment during service may lead to SERIOUS INJURY OR DEATH.
WARNING: FOX products should be serviced by a trained bicycle service technician, in accordance with FOX specifications. If you have any doubt whether or not you can properly service your FOX product, then DO NOT attempt it. Improperly serviced products can fail, causing the rider to lose control resulting in SERIOUS INJURY OR DEATH.
WARNING: FOX suspension products contain pressurized nitrogen, air, oil, or all 3. Suspension misuse can cause property damage, SERIOUS INJURY OR DEATH. DO NOT puncture, incinerate or crush any portion of a FOX suspension product. DO NOT attempt to disassemble any portion of a FOX suspension product, unless expressly instructed to do so by the applicable FOX technical documentation, and then ONLY while strictly adhering to all FOX instructions and warnings in that instance.
WARNING: Modification, improper service, or use of aftermarket replacement parts with FOX forks and shocks may cause the product to malfunction, resulting in SERIOUS INJURY OR DEATH. DO NOT modify any part of a fork or shock, including the fork brace (lower leg cross brace), crown, steerer, upper and lower leg tubes, or internal parts, except as instructed herein. Any unauthorized modification may void the warranty, and may cause failure or the fork or shock, resulting in SERIOUS INJURY OR DEATH.
Note: The Damping Adjuster Cartridge Assemblies should be considered non-rebuildable as they are difficult to dissassemble and reassemble. The Damping Adjuster Cartridge Assemblies do not need to be removed from the shock to perform a full rebuild. Removal and reinstallation of the Damping Adjuster Cartridges is shown below for reference.
NOTE: The Main Piston VVC system only needs to be disassembled and rebuilt if changing Main Piston Valving.
NOTE: The anodization color of the main piston may vary between clear, black, and orange. There are no functional or performance differences between different colored pistons.
Disassembly
Step 1
Unthread the Rezi Fill Air Cap counter clockwise with a Schrader Valve Stem tool then set aside. Release the IFP pressure by depressing the valve stem inside the Reservoir End Cap.
Step 2
Push the Reservoir End Cap into the Reservoir to gain access to the wire retaining ring. Remove the wire retaining ring with a thin shim then set aside. Use a small hex wrench to lift the Reservoir End Cap out from the Reservoir.
Step 3
Unthread the Bleed Screw counter-clockwise with a 2mm hex wrench. Drain the damper oil out over a waste oil basin by cycling the shock with the bleed port facing down into the waste oil basin.
Step 4
Clamp the body eyelet in your soft-jawed vise then unthread the Bearing Assembly counter-clockwise with smooth-jawed parallel pliers (Knipex) making sure to keep the pliers fully engaged on the Bearing Assembly wrench flats. (Note: Orange Prototype Piston shown, production versions will be black or clear anodized).
Step 5
Use the IFP depth setting tool to remove the IFP by engaging the protrusion of the IFP with the tool then turning the tool 90 degrees. Lift up on the tool to remove the IFP from the reservoir.
Step 6
Clamp the Reservoir in the 2021 X2 Resi shaft clamps (PN: 803-01-545) then heat the reservoir area to break down the Loctite. Unthread the Reservoir counter-clockwise from the Eyelet. You may need reposition the resi in the clamps multiple times to unthread it completely without damaging the rest of the shock by contacting the vise.
Step 7
Remove the Resi Piston and other 2-Pos Adjuster parts from the Reservoir then set aside.
Step 8
Clamp the Body in your shaft clamps (PN: 803-01-545) then heat the body area of the eyelet to break down the Loctite. Unthread the Body counter-clockwise from the Eyelet. Take care as the eyelet may be hot!
Step 9
Clean the Locite residue from the Outer Body threads. Separate the Inner Body from the Outer Body. Remove the Preload Collar taking care not to lose the detent ball and spring found within. Remove the Spring Guard. Clean the bodies with Isopropyl alcohol and lint-free paper towels.
Step 10
Unthread the set screw in the 2Pos lever by turning it counter-clockwise with a 2mm hex wrench. Remove the 2Pos from within the eyelet by pulling up while holding onto the 2Pos lever.
Step 11
Replace the three eyelet o-rings with new greased ones from the kit.
Step 12
Use the Reb Base Valve 4-Pin Spanner (PN: 398-00-882) to unthread the LSR Cartridge counter-clockwise from the eyelet then set it aside.
Step 13
Use the Comp Base Valve 4-Pin Spanner (PN: 398-00-881) to unthread the Compression Base Valve counter-clockwise from the eyelet then set it aside.
Step 14
Clean the bare eyelet with Isopropyl alcohol and a lint-free paper towel.
Step 15
Unthread the Main Piston Assembly from the shaft by turning the HSR VVC Plate counter-clockwise with a 19mm wrench. Set aside the VVC Assembly. Remove the Bearing Assembly by pulling it up off of the shaft. (Note: Orange Prototype Piston shown, production versions will be black or clear anodized).
Step 16
Remove the Bottom Out Bumper followed by the Spring Retainer and wire retaining ring if still in place.
Step 17
Carefully separate the Bottom Out Cup from the Shaft Eyelet as shown. Capture the detent ball and spring with a magnet and set aside.
Step 18
Clamp the 3/8" shaft in your shaft clamps (PN: 803-00-805) with the Shaft Eyelet up. Carefully apply heat to the Shaft Eyelet with a propane torch then unthread the Shaft Eyelet counter-clockwise to remove. Be careful as the Eyelet and Shaft may be hot! Remove the red Rebound knob from the Shaft Eyelet. Clean any Loctite residue from the Shaft and Eyelet threads.
Step 19
Push the HSR Inner Shaft out from the Shaft. Replace the o-ring within the Shaft with a new greased one from the kit.
NOTE: The Main Piston VVC system only needs to be disassembled and rebuilt if changing Main Piston Valving. You may skip to Reassembly if you are not changing Main Piston Valving.
Main Piston VVC Rebuild
Step 1
Remove the Topout Plate and Compression Valving from the Main Piston. Remove the Piston followed by the Rebound Valving. Set all valving aside and inspect for damage.
Step 2
Hold the 5mm nut closest to the HSR plate from turning while you unthread the other 5mm nut counter-clockwise with a 5mm deep socket. Remove both nuts and set aside.
Step 3
Remove the HSR Adjuster with Leaf Springs out of the Piston Bolt.
Step 4
Install your desired Rebound Valving onto the Piston Bolt followed by the Piston as shown. Make sure to install the Piston so the side with the three round ports is facing the Rebound Valving. Install your desired Compression Valving and Topout Plate onto the Piston Bolt.
Step 5
Install the Shaft Simulator provided with the 803-01-578 VVC Assembly Tool by threading it onto the Piston Bolt clockwise by hand. Clamp the Shaft Simulator in your soft jawed vise. Reinstall the HSR plate onto the Piston Bolt making sure to engage the hex feature. Use a 19mm socket to tighten the Piston Bolt to the Shaft Simulator, turning clockwise to 80 in-lb (9.0 Nm) torque.
Step 6
Reinstall the HSR Adjuster with Leaf Springs into the Piston Bolt through the HSR Plate as shown. Make sure that the hex of the HSR Adjuster is mated with the hex feature on both Leaf Springs. Make sure that the thicker of the two Leaf Springs is positioned closest to the HSR Plate. Thread the two 5mm nuts onto the HSR Adjuster leaving space between each nut as well as between the first nut and the end of the Piston Bolt as highlighted by the red arrows.
Step 7
Mount the VVC Assembly Tool into your soft-jawed vise. Adjust the positon of the VVC as shown, then position the VVC Assembly face down into the VVC Assembly tool as shown making sure to align the Leaf Springs and HSR Plate pins with the matching spaces in the tool as shown.
Step 8
Align the Shaft Simulator with the notch in the VVC Assembly tool. Turn the 22mm hex portion of the tool counter-clockwise (when viewed from above) while guiding the Shaft Simulator into the notch. Tighten the 22mm hex counter-clockwise to 20 in-lb (2.3 Nm) torque with a 22mm crowsfoot.
Step 9
Set your torque driver to 14cNm (This is 14cNm, not 14 in-lb or 14 Nm, a special torque wrench may be needed. FOX recommends the Tohnichi Torque Screwdriver RTD30CN 4~30 cNm model). Tighten the lower 5mm nut clockwise to 14 cNm (you can have both nuts within the socket during tightening as long as there is space left between the nuts).
Step 10
Adjust the knurled fixture of the VVC Assembly tool so the pin is in the initial position as indicated by the red arrow.
Step 11
Install the knurled fixture as shown making sure to seat the lowest 5mm nut into the v-jaws of the fixture with full fixture contact on two wrench flats. Turn the clamp lever counter-clockwise to lock the lowest 5mm nut into place with the cam as indicated by the red arrow.
Step 12
Slide the clamp over the rim of the knurled fixture then tighten the QR clamp just enough to hold the knurled fixture in place (use similar tension to a standard fork QR. You may adjust the QR as needed to achieve proper tension). The base of the knurled fixture must not turn during the next steps. If it does, the procedure must be repeated without allowing the knurled fixture base to rotate.
Step 13
Lift the knurled pin out of its initial position. Rotate the upper portion of the knurled fixture counter-clockwise until it stops. Push the pin down to lock it in place.
Step 14
Tighten the upper 5mm nut clockwise to 15 in-lb (1.7 Nm) torque with your deep 5mm socket.
Step 15
Turn the clamp lever clockwise to release the 5mm nut. Loosen the QR clamp then slide the clamp off of the rim of the knurled fixture. Remove the knurled fixture and set aside.
Step 16
Release the VVC Assembly from the VVC tool by turning the 22mm hex clockwise. Check for light drag through the full range of adjustment by turning the HSR Adjuster.
Step 17
Clamp the Shaft Simulator in your soft-jawed vise, then turn the HSR plate counter-clockwise with your 19mm socket to remove it. Keep the Shaft Simulator with your VVC Assembly tool. It is normal to have a small gap between the 5mm nuts and the Piston Bolt once the Shaft Simulator has been removed.
Reassembly
Step 1
Use a plastic pick to replace the o-rings on the outside of the Compression Base Valve and the LSR Cartridge with new greased ones from the kit then set aside in a clean area.
Step 2
Use a plastic pick to replace the seals on the Bearing Assembly with new greased ones from the kit. Verify that all three o-rings within the Eyelet have been seated properly.
Step 3
Use a plastic pick to replace the o-rings on the 2Pos Adjuster and Piston with new greased ones from the kit. Replace the IFP o-ring with a new greased one from the kit. Replace the o-rings on the Reservoir End Cap and Bleed screw with new greased ones from the kit.
Step 4
Reinstall the red Rebound knob into the Shaft Eyelet with the serrated side facing away from the eyelet. Coat the detent ball and spring with a thin layer of Hi-temp marine grease (Sta-Lube SL3125). Reinstall the detent ball followed by the detent spring as shown. Reinstall the Bottom Out Cup onto the Shaft Eyelet by pressing it down.
Step 5
Reinstall the HSR Inner Shaft into the Shaft as shown. Apply red Loctite 263 to the first 1-2 threads of the Outer Shaft making sure not to get Loctite on the Inner Shaft. Thread the shaft into the Eyelet making sure to engage the hex of the HSR Inner Shaft with the red Rebound Knob. Tighten clockwise to 150 in-lb (16.9 Nm) torque with the Eyelet Torque Tool (PN: 398-00-280).
Step 6
Reinstall the wire retaining ring followed by the Spring Retainer and Bottom Out Bumper.
Step 7
Coat the seals of the Bearing Assembly with a thin film of Slick Honey, then reinstall the Bearing Assembly onto the shaft as shown.
Step 8
Reinstall the VVC Main Piston Assembly onto the Shaft making sure not to pinch any shims and taking care to align the HSR Adjuster with the HSR Inner Shaft. Tighten by turning the HSR Plate clockwise with a 19mm socket or crowsfoot to 80 in-lb (9.0 Nm) torque. (Note: Orange Prototype Piston shown, production versions will be black or clear anodized).
Step 9
Coat the o-rings on the Comp Base Valve with a thin film of Slick Honey then reinstall into the eyelet tightening clockwise to 140 in-lb (15.8 Nm) with the 4-pin spanner.
Step 10
Coat the o-rings of the Reb Base Valve with a thin film of Slick Honey then reinstall into the eyelet tightening clockwise to 60 in-lb (6.8 Nm) torque with the 4-pin spanner.
Step 11
Coat the o-ring on the 2Pos Adjuster with a thin film of Slick Honey then reinstall into the Reservoir after positioning the 2Pos lever. Make sure to seat the adjuster within the lever then leave the lever set screw loose until after charging the IFP chamber.
Step 12
Reinstall the spring with the large end first. Position the Butterfly valve onto the 2Pos Adjuster making sure to seat the pins in the holes. Reinstall the Resi Postion as shown.
Step 13
Apply 1-2 drops of blue Loctite 243 to the threads of the Reservoir. Make sure to orient the 2Pos adjuster so the lever is in-line with the shock centerline axis in Firm mode and 90 degrees to the shock in Open Mode before torqueing the Rezi to the Eyelet. Reinstall the Reservoir, tightening clockwise by hand. Clamp the Reservoir in your shaft clamps, then use the Eyelet Torque Tool (PN: 398-00-280) to tighten clockwise to 120 in-lb (13.6 Nm) torque.
Step 14
Coat the detent spring in Hi-temp marine grease (Sta-Lube SL3125) then reinstall into the hole on the inside of the Preload Collar followed by the ball. Thread the Preload Collar onto the body depressing the detent ball as the it approaches the body during threading. Thread the Preload Collar at least 10mm down from the end for reinstallation of the body into the eyelet.
Step 15
Reinstall the Inner Body into eyelet, pushing down to seat it within the o-ring. Apply 2-3 drops of red Loctite 263 to the first 3 threads for a full 360 degrees. Reinstall the Outer Body with Preload Collar over the Inner Body tightening clockwise by hand. Clamp the Outer Body in your shaft clamps, then use the Eyelet Torque Tool to tighten clockwise to 240 in-lb (27.1 Nm) torque.
Step 16
Reinstall the Spring Guard so the chamfer on the Guard faces the Outer Body threads. Reinstall the rebuild Shaft Assembly into the Body. tighten clockwise to 144 in-lb (16.3 Nm) torque. (Note: Orange Prototype Piston shown, production versions will be black or clear anodized).
Step 17
Coat the IFP with a thin film of Slick Honey then reinstall into the Reservior with the Bleed Screw facing up. Reinstall the wire retaining ring.
Step 18
Remove the Bleed Screw by turning it counter-clockwise with a 2mm hex. Thread the Fill-Machine adapter clockwise into the bleed port. Vacuum the shock, then fill with FOX 4wt. oil. Set the IFP to 1.140in +/- 0.05in using your IFP depth setting tool (803-00-566). Reinstall the set screw with a new greased o-ring from the kit and tighten to 10 in-lb (1.1 Nm).
Step 19
Remove the wire retaining ring from the Reservoir. Coat the o-ring of the Reservoir End Cap with a thin film of Slick Honey then reinstall into the Reservoir. Push the End Cap down then reinstall the wire retaining ring.
Step 20
Use a small hex wrench to hold the Reservoir End Cap in place while you install the Rezi Fill Adaptor (PN: 803-01-826) by threading it in clockwise. Set the IFP pressure to 100 psi. Remove the Fill Adaptor and reinstall the Rezi Fill Air Cap with a Schrader Valve tool, tightening clockwise to 3 in-lb (0.3 Nm) torque. Tighten the 2Pos lever set screw clockwise to 7 in-lb (0.8 Nm) torque with a 2mm hex wrench. Clean the exterior of the shock and test all functions on the Dyno.
