Fox DHX Coil Rebuild Introduction: This is a guide to tearing down and rebuilding a Fox Racing Shox DHX 3/4/5 Coil shock. It shows the user how to: Dismantle the shock Clean internal parts Replace internal o rings Replace main shaft seal o ring Replace oil Reassembly of the shock unit Note: The Propedal and rebound assembly s are not dismantled or altered. If you have a dead rebound/propedal assembly, this guide will not help. To successfully dismantle the rebound and/or propedal assembly s, shaft clamps are required; the process also involves the use of a propane torch to heat the Loctited components. If not done correctly, damage will result to the shock (and your wallet) Disclaimer: This guide is not endorsed by Fox Racing Shox! By proceeding with this guide, the instant you open your shock, you voluntarily and knowingly forfeit any warranty that came with the shock. Do not proceed with these procedures if you are not mechanically inclined! If you have a tendency to round/strip every screw you touch, put the tools down NOW! Any damage you cause to your shock due to your own mistakes is YOUR FAULT. Do not expect any sympathy from me, or any sympathy from Fox (or warranty). YOU have to pay to have the unit fixed. This guide was devised with care, with information gained from a number of sources. This procedure works if carried out CAREFULLY and with PATIENCE. I AM NOT RESPONSIBLE FOR ANY DAMAGE YOU CAUSE TO YOUR SHOCK, BIKE, PERSONA OR SURROUNDS, USE COMMON SENSE AND TAKE THE FIRST FEW RIDES EASY, TO ENSURE YOU HAVE CORRECTLY REPAIRED THE SHOCK. WARNING! READ ALL Instructions twice before you commence with the rebuild, and ensure you understand its procedures
Preliminaries Tool list: Spanners Wooden vice Soft jaw vice Long nose pliers O ring / Dental picks (for removal of o rings) Clean rags Clean work bench Oil drip Pan Safety glasses Parts list: Replacement o rings, the best way to get these is to take the removed o rings to a local 0 ring supplier and get them sized up properly for replacement ones, I also recommend you buy a good amount of each, it s always good to have spares for next time, label them and put them in a compartment container Fork/shock oil. Ensure you use a high quality, fully synthetic oil. I use 10W Castrol Fully synthetic fork fluid. The DHX comes stock with 10W Fox Fluid (rebadged Torco RSF medium) If you wish to use a different weight oil, this website has a lot of useful info on shock oil; http://www.peterverdonedesigns.com/bikesuspension.htm Further Information: Here is a list of websites that have lots of useful information on rear shocks, for anyone who is interested in learning more about their rear shocks. Information on EVERYTHING regarding suspension, explaining different types of damper systems, set up info on a range of shocks etc; these site s are well worth reading through! : http://www.krankin.co.nz/_sgt/m6m9_1.htm http://users.actrix.co.nz/dougal.ellen/setup.html http://users.actrix.co.nz/dougal.ellen/tuning.html Some useful info on how to mod shim stacks, for those who are interested in modifying their shim stacks, (undertake this at your own risk!) http://www.deycore.com/tuning_tips.htm Website with lots of info regarding things like oil weights etc: http://www.peterverdonedesigns.com/bikesuspension.htm Righto, if you feel confident, and have read this guide at least twice (yes that was an instruction!), clean your work area, gather your tools, and lets begin!
STEP 1: Removing shock 1. Firstly, you will need to remove the shock from your bike; it will be different on every bike, so if you don t know how to remove your shock, STOP NOW! 2. After you have removed the shock from the bike, place on your work bench, and give it a good wipe over with a clean cloth, to remove dust and dirt 3. Next remove the spring, and in my case, the shock boot 4. Back off all adjustments (Least Propedal, Bottom Out and Rebound) 5. DEFLATE THE BOOST VALVE! 6. Give the shock body a good clean, you don t need any dirt or debris s getting inside the shock 7. Clamp the shock body in a wooden vice
STEP 2: Removing Bottom Out Adjuster 8. Loosen the two grub screws on the bottom out adjuster with a hex key 9. Remove the adjuster, and set it aside 10. Using either a spanner or wrench, loosen the grey cap 11. After the threads have been disengaged, pull the assembly out, and set it aside 12. You can now see the IFP (Internal Floating Piston) and the bleed screw in the middle 13. Use a measuring device and measure the depth of the IFP, The depth will be different for different stroke lengths and eye to eye measurements 14. Alternatively, use the IFP depth Chart at the end of this document
STEP 3: Removing the IFP 15. Depress the shaft all the way down 16. Remove the bleed screw from the centre of the IFP with a hex key 17. Pull the bleed screw out, and set it aside in a safe place 18. Using long needle nosed pliers, pull the IFP out of the Piggyback Chamber 19. Remove the IFP 20. Place the IFP aside, and pull the shaft out to full extension
STEP 4: Removing the Shaft assembly 21. Wrap an old tube around the shaft, this will prevent damage to the shaft should you slip with the spanner 22. Using a spanner or wrench, undo the shaft cap, it may be tight, keep applying even pressure and it will undo 23. After its loosened, use your hand to unthread the shaft 24. Pull the shaft and piston assembly out of the shock body 25. Set the shaft assembly aside 26. Drain the oil from the Piggyback and main chamber into an oil pan, wipe the body with a clean cloth and set the body aside
STEP 5: Removing Piston and Seal Housing Assembly 27. Clamp the shaft eyelet reducers in a soft jaw vice, or use blocks of wood as shown in the first picture, this will prevent damage to the reducers 28. Use a small spanner and undo the black piston bolt 29. Remove the piston and shim assembly, be careful not to muck up the shim stack 30. Lift off the black seal housing, being careful not to knock the rebound needle in the centre of the shaft 31. Place the seal housing on your work bench, be careful not to scratch the orange bushing 32. You can now access the yellow dust seal and black main shaft o ring between the yellow dust wiper and orange bushing 33. If you shock has had sufficient use there will probably be dirt and crud in the yellow dust seal, wipe it clean
STEP 6: Removing Shaft O-ring, IFP O-ring and Housing O-Ring 34. Using a pin or dental pick, stab the black o ring and pry it out, being careful not to scratch the yellow dust seal or orange bushing 35. Label the o ring so you know which one it is and set it aside for now 36. Using your pick, remove the housing o ring 37. Label the housing o ring, and put it aside 38. Using your pick, remove the IFP o ring 39. Label the IFP o ring and set it aside
STEP 7: Removing Bottom Out assembly o- rings and cleaning shock internals 40. Using your pick, remove the bottom out plunger o ring, label and set aside the o ring 41. Using your pick, remove the Bottom out housing o ring, label and set aside the o ring 42. The Bottom out assembly with its o rings 43. Using a clean cloth, wipe out the main shaft chamber 44. Using a clean cloth, wipe out the piggyback chamber 45. You have now disassembled you shock. Take the o rings to a local supplier and have them sized up and replaced, I recommend getting a quantity of each, labelling them and putting them in a container for next time, it s always good to have a supply of them
STEP 8: Replacing main shaft o-ring and shaft housing o-ring 46. Take your new main shaft o ring, apply a few drops of suspension oil to it and pinch as shown 47. Insert the pinched o ring into shaft housing as shown 48. Place your pinkie in opposite end as shown 49. Using you other pinkie, squash the o ring into the housing and use your fingers to set the o ring in its housing, this can be tricky, take your time and it will go in 50. Take you new shaft housing seal, and place a few drops of suspension oil onto it 51. Insert it back onto housing
STEP 9: Replacing IFP and Bottom Out assembly o-rings, reassembling shaft assembly 52. Place a few drops of suspension fluid on a new IFP o ring, and place it back on the IFP (In picture, new o ring is in place on IFP, old one is next to IFP) 53. Place a few drops of suspension fluid on new bottom out housing and adjuster o rings, then place them back on the assembly (the position of the old o rings on the table is respective of where they go on the BO assembly) 54. Wipe some suspension fluid on shaft, and replace rubber bottom out bumper 55. Reinsert the shaft seal housing back onto the shaft, be careful to put it on straight, take your time, DO NOT FORCE IT, otherwise damage to the shaft or bushing may result 56. Replace the piston/shim assembly, and retighten. Just snug it tight, if you over tighten it too much, you may crush the shims and prevent them flexing 57. After you have retightened the piston, pull the shaft housing all the way up. You have now successfully rebuilt the shaft assembly
STEP 9: Refilling oil and reinstalling shaft assembly 58. Refill the main chamber with oil 59. Let it filter into piggyback chamber and keep filling until piggyback chamber is almost overflowing 60. Place the IFP into the chamber, press it so it just sits on the top of the threads (ensure bleed screw is in) 61. Fill main chamber with suspension oil until it is almost overflowing 62. While holding IFP in place, reinsert the piston into the chamber and thread the seal housing on, hand tighten it at this stage. It s good to place a drip pan underneath the shock, as oil will overflow 63. Remove IFP bleed screw
STEP 10: Reinserting IFP and reinstalling Bottom Out assembly 64. Depress IFP past threads, ensure bleed screw is removed, and wear safety glasses, as oil will squirt through bleed hole 65. Using you measuring tool, push IFP to its correct depth. If you did not record your IFP depth, use the depth chart at the end of this document. Tap body to displace any trapped air as your pushing the IFP in, this will ensure a good bleed 66. Reinstall bleed screw, drain and wipe excess oil from IFP chamber 67. Using spanner or wrenches, retighten the shaft housing. Its recommended that you use the old tube to protect the shaft 68. Reinsert the bottom out assembly 69. Using a spanner or wrench, tighten the grey cap
STEP 12: Final Reassembly 70. Reinstall the Bottom Out adjuster cap 71. Tighten the 2 grub screws 72. Reinflate the boost valve to a minimum of 125PSI 73. Clean the shock over with Isopropyl Alcohol or a wet cloth 74. Reinstall spring, any reducers and valve cap (and in my case, my shock boot) 75. Reinstall the shock back onto your bike 76. Do the bounce test on your bike to lube internal parts, then set adjustments to your settings, bounce check again to make sure everything is working correctly 77. Success = BEER!
IFP Depth Chart: EYE to EYE Stroke Metric; 190mm, 50mm = 32mm 200mm, 50mm = 32mm 200mm, 57mm = 33mm 215mm, 64mm = 34mm 222mm, 64mm = 34mm 241mm, 76mm = 38mm Imperial; 7.500, 2.00 = 1.25 7.875, 2.00 = 1.25 7.875, 2.25 = 1.30 8.500, 2.50 = 1.35 8.750, 2.50 = 1.35 9.500, 3.00 = 1.48 Thanks to EmanResu on MTBR for finding the IFP chart Be sure to check out his awesome guide on bleeding a DHX Air! http://forums.mtbr.com/showthread.php?t=491668
Acknowledgements Big thanks to the people who contributed their valuable knowledge to help me compile this guide, id name you individually, but you know who you are! Info obtained from people on: MTBR Pinkbike ROTORBURN AUSTRALIA (formally FARKIN) Ride Monkey This guide was compiled by me, Nick_M2R, on 18 th May 2009, repost this guide if you wish. While I have proof read this guide carefully, I m only human, and its late at night. If you notice any mistakes or have any improvements, PM me on MTBR and ill include them in future releases. Enjoy Guys and Girls! Version: 1