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 Post subject: Fox DHX 3.0 Rebuild
PostPosted: Sun Jun 09, 2013 2:28 pm 
big hucker
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Joined: Wed Jan 16, 2013 7:32 pm
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Location: Dallas, TX
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DHX 3.0 Rebuild


Note: Some photos shown on this page may not actually be of this shock model. We reserve the option to preserve system bandwidth by substituting generic pictures whenever it's possible and appropriate.


1. Prepare your work area. Lay out a clean shop towel upon which to stage and organize your parts assemblies.

2. Wear your safety glasses (always protect your eyes), and use rubber gloves if so desired.

3. Remove the mounting hardware, and clean the exterior of the shock before starting its disassembly. This is a good time to make record of the eye-to-eye of the shock and travel. You will need this information later for looking up parts and the IFP setting.

4. Clean and inspect the bottom out bumper on the damper shaft. Also, make sure it's clean underneath.


5. You will find a Schrader style air valve for charging the IFP. Unscrew the valve cap and release the air from the reservoir chamber.


6. Remove the bearing housing and damper shaft with a one inch (1") open end wrench (turn counter-clockwise).


7. Remove the bearing housing/shaft assembly from the damper body over an oil draining pan.


8. Remove the reservoir end cap with a 24 mm socket wrench. You may need to hold onto the reservoir body with shaft clamps if it starts to unthread before the end cap does.


9. Remove the IFP by griping onto the wrench flats with needle nose pliers.


10. Remove the IFP bleed screw with a 2 mm hex key and 9 mm wrench.


11. Clean the IFP. Replace the IFP O-ring, if necessary.


12. Pour the remaining oil out of the shock into your drain pan.

13. Gently grip the damper shaft with the shaft clamps, and remove the piston assembly with a 3/8” socket wrench.


14. Keep the piston assembly organized; lay it out expanded in order, on a clean shop towel.


15. Inspect and clean all damper piston parts, that is, the piston, valves, and piston bolt.

16. Remove the shaft from the clamps, and slide the bearing housing off. Clean, and replace the bearing housing seal and shaft dust wiper with new parts.


Note: Proceed with steps 17 through 26 only if you have problem issues with the boost valve in the reservoir.

17. Thread in the reservoir end cap into the reservoir body.

18. You can try to remove the reservoir from the reservoir eyelet without removing the decal, but often the decal will get damaged during this process. To remove the decal, warm it up a little to soften the adhesive; getting it warm to the touch works best. Peel the decal away from the reservoir, and then clean off the leftover glue with shop cleaner (Simple Green, isopropyl alcohol, or parts washer solvent).

19. Heat up the reservoir at the bottom, where the threads are located. The threads have Loctite on them from the factory, and the mild heat will soften the Loctite. Heat until it’s just hot to the touch.

20. Tech Tip: Clean the shaft clamps with isopropyl alcohol, and leave them wet. This action will help the shaft clamps grip the reservoir body. This sounds a little odd, but it really works (see the Wikipedia article Surface Tension and Energy of Cohesion.

21. Using ½ inch bar stock, insert this into the DU bushing bore and turn the eyelet counter-clockwise to unthread the reservoir body from the eyelet.

Image Image

22. You will need to clean the Loctite from the reservoir and eyelet end cap threads.

23. Remove the larger spring (i.e., the rebound check valve spring) from the inside eyelet cap.


24. Remove the ProPedal spring (the smaller one).


Note: Proceed with steps 25 through 29 only if you have a problem with the rebound eyelet, or other damper shaft eyelet issues

25. Clean the damper shaft with isopropyl alcohol, and also clean and spray the shaft clamps, and leave wet. Clamp damper shaft into vise with the alcohol-wet shaft clamps.

26. Heat up the top of the damper shaft to soften the Red Loctite. Do not overheat. Shaft should be just uncomfortably warm to the touch.


27. Unthread the eyelet from the damper shaft. Do not allow damper shaft to spin in the shaft clamps; any damage to the shaft finish must be avoided.

28. Clean Loctite from the threads of both the shaft and eyelet.

29. Remove and inspect the rebound adjuster rod and O-ring. Clean or replace the O-ring as necessary.

30. Remove and inspect the O-ring located inside the threaded damper shaft bore in the eyelet. Clean or replace as needed.

Now that you have all major components disassembled, it’s a good time to clean all the parts and inspect and replace the seal, O-rings, etcetera before you start the re-assembly process.


Note: Skip steps 7 through 10 if you did not disassemble the shaft, rebound rod, and eyelet.

1. Insert the damper shaft rebound rod into the damper shaft. Make sure you have inspected the rebound rod O-ring, and replace it if necessary.

2. Before threading the damper shaft back into the eyelet, make sure that you have installed the O-ring into the bottom of eyelet thread bore, and that all threads are clean of old Loctite.

3. Drop two drops of Red Loctite #26231 onto the damper shaft.

4. Thread the shaft into the eyelet.

5. Place the bottom out bumper onto the damper shaft, and slide it up to the eyelet.

6. Lube the bearing housing seals and the DU with grease. Gently slide the bearing housing onto the damper shaft, all the way up to the bottom bumper.

7. Place the damper piston onto the damper shaft. Thread the bolt in all the way by hand.

8. Place the eyelet into soft jaw vise, and torque the piston bolt to 75 inch pounds. As you torque the piston bolt, your eyelet will also come into torque spec at the same time.

9. Test the rebound adjuster to make sure it’s moving freely. Set the assembly aside.

Note: Skip steps 10 through 13 if you have disassembled the boost valve assembly.

10. Inspect the reservoir, and make sure that all the old Loctite has been removed and the threads are clean. Re-check the O-ring at the bottom of threads of the reservoir eyelet.

11. Install ProPedal adjuster spring (small) and Rebound Check Spring (large) into the reservoir end cap.

12. Place two drops of blue Loctite #24241 onto the reservoir threads.

13. Make sure the rebound check spring, ProPedal spring, and rebound check valve are staying in place, as you thread the two parts together.


14. Place the eyelet into the soft jaw vise and fill the reservoir up with suspension fluid (10wt). Fill up to just reach the bottom of the cap threads.


15. Make sure you have inspected and replaced the IFP O-ring, if necessary.

16. With a 2mm hex key wrench, thread the IFP bleed screw into the IFP a couple of turns (the bleed screw will be removed again shortly).


17. Slowly push the IPF into the reservoir. Push it down until you see the bottom of the last threads. You will see oil and maybe some air bubble up in the body. Remove the set screw, and set the IFP aside for now.


18. Place the reservoir eyelet into a soft-jaw vise and wrap the body with a shop towel, to catch the oil in the final oil filling process.


19. Top off the body with suspension oil.


20. Push the bearing housing all the way down to the top out plate. Insert the piston and bearing housing assembly into the suspension oil in the damper body. Thread in the bearing housing all the way down with a 1” open end wrench.

Image Image Image

21. Using an IFP setting tool, push the IFP all the way down to the correct IFP depth for the shock. This will purge the suspension fluid and any small air bubbles out through the IFP bleed screw hole.


22. Double check the IFP height, and thread the IFP bleed screw back into the bleed port. There will be a small amount of oil on top of the bleed screw. This is normal, and ensures that air does not enter the IFP chamber as you screw the bleed screw back in. A 9 mm open-end wrench can be used to hold the IFP steady as you torque the IFP bleed screw to 7 inch pounds (0.79 N-m) with a 2 mm hex key wrench.

23. Torque the bearing housing with a 1" crows foot wrench, to 35 ft-lbs. (420 in-lbs./47.45 N-m).


24. Inspect the reservoir end cap and volume adjuster; grease and replace O-rings as necessary.

25. Thread the bottom out adjust control cap into the IFP chamber, and torque to 420 inch pounds (47.45 N-m).


26. Pump the reservoir up with air to a minimum of 125 PSI.

27. Clean the reservoir with isopropyl alcohol, and replace the decal if necessary.

Image Image

28. Install the spring and mounting hardware as required.


29. Return the shock back to your now-happy customer. Smile! :-]


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