REBUILD FOX AIR SHOX
Contents
1. 62 93 66 99 69104 73 110 77 10 81 122 85 128 150 Ihs 60 90 6416 G 102 72 108 TG 114 Sy T20 5 126 88 132 160 llos 62 93 67 101 71 107 75 113 79 119 83 125 87 131 91 137 170 Ihs 6106 69104 714011 78 117 81 122 85 128 20135 14 11 180 lbs 67 101 T2 108 76 114 80 120 85 128 89 134 94 141 98 147 190 Ibs 69 104 74 1 79 119 83 125 87 131 92 138 97 146 101 152 200 Ibs 2 108 16 114 81 122 86 129 9 13 96 144 101 132 106 159 2 10 Ibs TAM I 79 119 84 126 89 134 94 141 99 149 104 156 109 164 220 Ibs 16 114 81 122 86 129 91 144 96 144 101 532 106 159 111 167 BIKE WEIGHT 190 210 LBS Rider Suspension Lever ratio ip 17 L8 19 2 0 120 lbs 57 87 60 90 64 96 68 10 72 108 THEI 80120 84 126 130 lbs 50 89 62 93 64 106 71 10 7 3113 79 119 83125 8 13l 140 Ibs 61 92 65 98 59 104 TXO THANG 81 122 85 128 89 134 150 Ibs DO 64 101 11 10 16 114 80 120 84 126 B8 132 33140 160 Ibs 65 98 70 105 TAM E THT 82 123 86 129 91 137 95 143 170 Ibs 68 102 12 108 6 114 81 122 86 129 91 137 95 143 100 150 180 Ibs 70 105 TA 79 119 84 126 89 134 93 140 98 147 103 155 190 Ibis 2 108 11116 81 122 36 129 91 137 36 144 101 152 106 159 200 Ibs TAM 79 119 84 126 89 134 94 141 99 149 104 156 109 164 210 lbs 6 114 81 122 81 1131 92 138 96 144 101 149 106 159 111 167 220 Ibs 78 0117 84 126 89 134 89 134 95 143 104 156 109 164 LEASITE REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 192. REBUILDING FOX AIR SHOX The FOX Air Shox was one of the most successful after market products for the serious Motocross racer in the second half of the seventies Therefore it is not surprising to find the product still in demand for Vintage MX The shocks can regularly be found for sale on various Vintage MX classified sites However the shocks you are buying are used so what is available for restoring or rebuilding the shocks Surprisingly there are a number of sources which offer rebuild kits and rebuild services for the Air Shox including the original product manufacturer FOX Racing Shox To see just what could be done we set off to FOX Racing Shox with two sets of used FOX Air Shox to be rebuilt Follow along as Josef at FOX Racing Shox rebuilds our shocks DETERMINING THE SHOCKS CONDITION m DI Li FIGURE 1 m LP Start by inspecting the condition of the Air Shox The shock should be cleaned before inspecting Since we are going to be replacing the seals etc we cleaned the shock using a standard solvent parts cleaner Clean out between the fins using a stiff brush For normal maintenance a good soap and water mixture should be used ST ap The FOX Air Shox is not painted but uses an anodized finish to protect the aluminum body You should not paint the body as that will reduce the shocks cooling ability The body needs to be as clean as possible as any dirt on the body will decrease the cooling ability of
3. BIKE WEIGHT 210 230 LBS Rider Suspension Lever ratio 20 64 06 67 01 T2 108 75 113 66 99 70105 74114 79 119 68 102 72 108 TG 114 81 122 71 107 75 113 79 119 84 126 T4110 77 16 82 123 87 131 97 1146 101 152 75 113 80 120 85 128 90 135 100 150 104 156 THT 83125 87 131 32 138 1020153 107 161 80 120 85 128 90 135 95 143 105 158 110 165 88 132 230140 18 147 103 155 108 163 113 170 90 135 96 144 100 150 105 158 111 167 116 174 87 131 KHO ON TAT WMASG 110 165 115 173 120 180 120 Ths 130 Lbs 140 Ths 6470 150 lbs 66 99 160 Ths 69104 170 Lbs 69 104 180 Ths 71 4107 190 Lbs T3 110 200 Ths 73 113 210 lbs 79 119 220 Ths 82 123 Add approximately 15 lbs For weight of riding equipment SINGLE CHAMBER AIR SHOX DESIGN If the tables below do not have data for your scenario just do the following Step 4 Multiply your bike weight by 0 14 14 Step 5 Multiply your riding weight by 0 21 21 Step 6 Add the numbers from Steps 1 and 2 and then multiply this by your SLR This number is the recommended pressure for the low pressure chamber To determine the recommended pressure for the high pressure chamber multiply the low pressure number by 1 5 1 8 if you are pro or fast expert BIKE WEIGHT 170 190 LBS Rider Sapa pa er Weight LI 12 L3 14 L5 LG 1 7 1 8 120 Ibs 55psi 60psi Gbpsi TI psi T
4. 1 63 Factory Moved up Shock oration Only 1975 Maico 1 20 Old Shock Location 1075 Montesa VR 1 70 Laydown Shock Geometry 1974 Montesa VR 1 31 Original Ceometry 1075 Penran K I M 1 56 240 amp 400 aydown Geometry 1975 Suzuki RM 2 18 125cc Laydown Geometry Only 178 Honda CRZ50R 1 8 1977 Husqvarna 1 8 CT Mudel Stock Shuck Location 1376 77 Penton K IM ar 1976 77 Muicu 2 2 AW Mudel 1976 77 Suzuki 1 9 RM B and RM C Models DETERMINING YOUR BIKE S SLR The Suspension Lever Ratio is equal to The distance between the swing arm pivot and the center of the rear axle The distance from the swing arm pivot to the centerline of the shock measure perpendicular to the centerline of the shock Figure 1 shows the two measurements DUAL CHAMBER FOX AIR SHOX If the tables below do not have data for your scenario just do the following Step 1 Multiply your bike weight by 0 10 10 Step 2 Multiply your riding weight by 0 15 15 Step 3 Add the numbers from Steps 1 and 2 and then multiply this by your SLR This number is the recommended pressure for the low pressure chamber To determine the recommended pressure for the high pressure chamber multiply the low pressure number by 1 5 1 8 if you are pro or fast expert BIKE WEIGHT 170 190 LBS Rider Sushi a o Weight 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 120lbs 5481 57 86 61 92 6496 68 102 71107 76 114 79119 130 Ths 56 84 50 89 6305 67101 71 107 73 113 T8117 82 123 1401bs 5887
5. The difference in the fliud volume is the displacement volume of the bladder The displacement volume is the amount of oil that will have to be added to the shocks standard oil quantity to adjust for the removal of the bladder When pressurizing the modified Air Shox you must only use the upper or low pressure air valve to pressurize the shock The initial air pressure should be set at the midpoint between the two air pressures calculated for the original shock application For example if the shock was previously set at 85 Psi for the low pressure and 120 Psi for the high pressure then the modified shock you should use is 102 Psi Further tuning will be required to optimize the settings It may also be necessary to modify the amount of oil in the shock to obtain the full travel and performance from the shock An alternative recommendation for the air pressure setting is the original single chamber air pressure values See page 20 for the recommended air pressure settings CUT HERE n REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 13 TUNING THE FOX AIR SHOX One of the greatest features of the FOX Air Shox was the ease in which it could be adjusted or tuned to suit the rider s preference There is no such thing as the perfect spring rate or damping characteristics for each application or rider It is really a case of what the rider wants and the bike demands The following instructions are based upon information supplied in the ori
6. of the shaft will affect the seal Life and shock performance Josef held the shaft still with a set of aluminum blocks clamped securely in the vise u A 51 If the shaft continues to turn try cleaning the shaft and clamp blocks with MOSELM contact cleaner It is also possible to carefully use heat to expand the nut and help make the removal of the nut easier REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 3 FIGURE 4 Disassemble the piston assembly Figures 5 6 7 and 8 show the various stages of disassembly Remove the top out bumper from the shaft Clean the parts Figure 9 shows all the parts that make up the piston assembly Check the shaft for any nicks or small pits These should be polished out to improve the seal life Clean all the parts and inspect them for damage m NND If the top out bumper is brittle replace it Josef uses a US 324 O ring on each VLESELIM shock as the original top out rubber is no longer available The US 324 O ring is 210 cross section and 1 350 inside diameter FIGURE 5 FIGURE 6 REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 4 FIGURE 7 FIGURE 8 FIGURE 9 REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 5 SEAL REPLACEMENT FIGURE 10 FIGURE 11 Using a seal removal pick carefully insert the tool into the wiper seal and pull the seal away from the housing see Figure 10 A second pick can be inserted behind the seal once it has been pulled away from the housing The second pi
7. 6psi Bi psi Sbpsi 91 psi 130 lbs 58 63 68 14 19 84 89 Y 140 Ibs 60 66 71 76 82 87 93 98 150 lbs 62 68 14 D 5 91 96 102 160 Ibs 65 71 76 82 88 94 100 106 170 Ibs Gr 13 19 85 91 9r 104 110 180 lbs 69 76 8 88 95 101 I 113 190 Its 12 iB 83 91 98 104 111 117 200 Ibs 7A gI 87 94 Ino 108 114 121 210 lbs 16 83 90 9r 104 111 18 125 220 Ibs 79 86 93 100 107 114 121 129 BIKE WEIGHT 170 190 LBS Rider Suspension Lever Ratio Weight 11 120 Ths Supst 130 Lbs 61 140 Ths 63 12 13 E 1 6 1 7 psi bUpsi TApsi psi S psi psi fio 75 0 8h 92 98 150 Lbs 65 71 17 83 89 95 101 160 Ths 68 74 0 8 92 t 105 170 Lbs 76 83 89 96 102 108 180 Ths 72 7 8h 92 99 105 112 190 lbs 75 81 88 95 102 109 115 4 508 105 112 119 101 108 115 200 Ths 221 Ths 82 BIKE WEIGHT 170 190 LBS Suspension Lever Ratio TU psi 105 BApsi psi THpsi psi gi 93 90 on 102 108 81 87 93 100 106 112 1 20 97 103 109 16 86 93 100 106 113 120 uo on 103 10 117 123 92 99 106 113 120 127 5 102 109 116 124 141 97 105 112 120 127 135 116 123 220 Ths 3 92 131 130 Add approximately 15 lbs For weight of riding equipment REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 20 The single chamber Air Shox featured an external damping adjustment Table 2 shows the recommended damping settings for the air pressure being used The damp
8. als and a copy of the original user s manual The rebuild kit is 45 00 Including Air Freight and a set of long bladders cost 69 00 all prices in US Funds North American customers can contact Perry Sconzert Contact Geoff at oldmx yahoo com Contact Perry at elsinore99 hotmail com PRO ACTION Pro Action Beaver Falls PA also offers a rebuild service for FOX Air Shoxs Pro Action Greg Workman also has experience in repairing damaged shafts Of course Pro Action can also help you with a wide variety of shock services for other makes of shocks Pro Action charges 100 00 US to rebuild a set of FOX Air Shoxs Parts and Labor Contact Greg Workman at Pro Action 3611 8th Ave Beaver Falls PA 15010 Tel 724 846 9055 e Fax 724 846 1629 www pro action com REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 18 RECOMMENDED FOX AIR SHOX SETTINGS The following are the recommended Air Pressures for both the single and dual chamber Air Shox designs The air pressure recommended is a function of your bikes Suspension Lever ratio SLR Therefore in order to figure out your pressure settings you will have to also determine your bikes SLR Table 1 gives some common SLR numbers taken from the original FOX manuals TABLE 1 Bike SLR Notes 1975 Bultaco 1 65 125 250 amp 360 Pursung 1975 Can Am 1 53 250 MX 2 1975 CZ 250 and 400 Falta Replica Models Only 1975 C7 1 20 1975 Husqvarna 1 78 CT Model with Laydown Ceuructry 1975 Maloo
9. chine in Texas has made copies of the bladder for the FOX Air Shox We used J R s long bladders for replacement when we rebuilt our 17 Air Shox Follow along as Jeff at FOX Racing Shox replaces the bladders It is possible to test the bladders once the shock has been disassembled Put a small amount of pressure in the bladder via the air valve on the shaft Immerse the shaft in water and look for any leaks A leak will appear as a steady stream of air bubbles from one specific spot in the shaft If no air bubbles are found then the bladder is okay Clamp the shaft tightly in a vise Be careful not to damage the shaft with the vise Jeff uses a pair of aluminum blocks to hold and protect the shaft see Figure 28 The shock has been completely rebuilt on the example used The shaft assembly does not need to be disassembled in order to replace the bladder ll The Aluminum blocks used to hold the shock shaft from turning has a 1 3 8 bore RUSSEL FIGURE 28 M REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 11 FIGURE 29 W FIGURE 30 FIGURE 31 Y FIGURE 31 REBUILDING FOX AIR SHOX Lift up on the eyelet to remove the eyelet and bladder as one assembly Remove the bladder from the eyelet by pulling the top lip off the bladder of the eyelet Figure 30 shows the replacement bladders vs the original bladders The old bladders have expanded from age and use The replacement bladders are the correct size I
10. ck can be used to get a better grip on the seal to help remove the seal without slipping and scratching the bearing housing If required the bearing housing can be lightly held in a vise or a helper can insert the second pick while you hold the bearing housing Remove the seal from the bearing housings Repeat for the oil seal see Figure 11 Carefully clean the bearing housing Use a cotton swab and contact cleaner to make sure all seal parts and residue are removed from the housing REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 6 FIGURE 14 FIGURE 15 FIGURE 16 FIGURE 17 REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 Correctly orient the oil seal with the wiper edge towards the screw end of the bearing housing Lightly secure the bearing housing in the vise and carefully insert the seal into the housing A small amount of grease can be used to help insert the seal into the housing Orient the wiper seal with the wiper edge away from the screw end of the bearing housing Insert the seal into the housing using the same technique as the oil seal Figure 17 shows the bearing housing with the new seals installed Lightly pack the seal and bearing lips with a good quality suspension grease This improves the seal life and greatly reduces the stiction SHOCK ASSEMBLY Place a small amount of grease on the top edge of the shaft Carefully slide the bearing housing onto the shaft Take care not to nick the
11. ge the jet hole size to obtain the required low speed damping TUNING THE SHOCK OIL QUANTITY The correct quantity of oil in the shock is important for optimal performance of the shock Too much oil will result in you not getting the full travel from the shock while too little oil will result in the shock bottoming out hard The best method to determine if the oil quantity is okay is to set the air pressure in the shocks to the recommended settings or settings that have worked fine in the past i e before replacing the bladders Move the bumper up the shock shaft Test the bike for several laps around the racetrack BUMPER NOT RETURNED TO THE BOTTOM OF THE SHOCK You are not getting the full travel of the shock Remove some oil and retest REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 15 BUMPER RETURNED BUT THE SHOCKS WERE BOTTOMING OUT HARD You are running out of damping fluid before you run out of shock travel Add some oil and retest The FOX Factory recommends removing 5cc of oil for every Y inch that you are short of travel You should also add oil in 5cc steps to cure the sever bottoming out problem There should never be a requirement to add a large amount of oil Greater than 20cc with shorter bladders ADDING SHOCK OIL Depressurize the low pressure chamber This is the air valve at the large finned end of the shock This can be done with the shocks on or off the bike Remove the air core from the air valve Fill up a s
12. ginal FOX manuals i JE TEE If you are not an expert class rider like the author it will help to use a video MUSEUM F camera to analyze the performance of the suspension There is a good section on how to do this and suspension tuning techniques in the latest version of Eric Gorr s book Motocross amp Off Road Performance Handbook The book is available from Eric s web site www eric gorr com The FOX Air Shox allows for changes in the high and low pressures values damping characteristics and oil quantity when tuning the shocks The single most important variable is the pressure settings TUNING THE AIR PRESSURES The FOX Factory advises starting out with the original recommended low and high pressure settings Then start to experiment from there getting the feel of how the bike changes as the air pressures are adjusted be 3 e TE Remember that in order to understand what a change in any shock setting is MUS CUM UUL it is important to only change one variable at a time By changing only one variable and documenting the result it is possible to collect enough data to determine the changes required for a new track or rider LOW PRESSURE GUIDELINES The low pressure setting controls the spring rate for the first 1 inches of shock travel Remember this amount of shock travel translates into more when the shock is mounted on the bike Change the low pressure 5 Psi at a time A pressure too low will result in a uneven ride o
13. ing setting is the number of turns out from the full in position TABLE 2 Air Pressure Damping Setting Psi Turns 30 41 2 55 4 1 4 60 4 65 3 3 4 70 3 1 2 75 3 1 4 80 3 5 2 4 4 95 2 1 2 105 2 1 4 115 2 125 1 4 4 140 11 2 IMPORTANT DATA STANDARD OIL REFILLS Shock Length Oil Quantity Inches cc 13 151 I3 172 158 14 1 4 168 14 34 177 15 1 8 182 15 172 209 15 34 192 16 206 16 1 4 192 16 7 213 li 213 17 172 213 DAMPING JET ORIFICE SIZE Shock Size Min Jet Dia Std Jet Dia Max Jet Dia 13 106 116 122 13 1 2 12 120 128 14 1 2 120 128 136 14 3 4 A28 136 144 15 1 8 132 14U 141 15 1 2 128 136 144 15 3 4 132 14U 141 16 136 147 157 16 1 4 132 14U 147 17 144 152 162 1 1 2 144 152 164 POP OFF SPRING NUMBERS x 13 v2 14 1 4 Ha 3 4 15 1 8 15 1 2 16 16 14 17 17 1 2 Soft 28 21 25 24 25 24 21 Firm 32 Tm 29 28 29 28 Y 24 Xflem 3 5 3 0 4 i5 z 3 3 0 2 6 2 6 REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 21
14. l comes from the lower air valve it means the bladder is leaking and needs to be replaced J R s Machine manufacturers a set of replacement bladders for the FOX Air Shox See Page 11 for instructions on replacing the high pressure bladder If no bladder is available for your specific size of FOX shock it is still possible to use the shocks Both shocks will have to be modified to run without the bladder installed See the page 13 No Bladder Available for more details If everything looks good at this stage then the shocks can be rebuilt If you want to do the rebuild yourself you will need to buy a seal rebuild kit some FOX Racing Shox 5W shock oil and have access to compressed Nitrogen If rebuilding the shocks is too big a job for yourself there are a number of people who have the knowledge and parts required to rebuild the shocks for you See page 18 Sources for Air Shox Parts and Service for details on parts or rebuild services The original FOX Air Shox manual recommends Belray LT100 shock oil Belray now recommends the 5W HVI Racing Suspension Fluid as the replacement for the original LT100 specification FOX Racing Shox now recommends their own special 5W shock oil for demanding race applications FOX Racing Shox sells the oil in various size containers specifically for people rebuilding or replacing the oil in the Air Shox REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 2 DISASSEMBLING THE SHOCK x Warning Never attem
15. mall eyedropper or medicine dispenser with the amount of oil to be added Add the oil to the shock by squirting it through the vale opening Re install the valve core and set the low pressure setting to the previous value unt x A UE It is always a good idea to test that the air valve after changing the pressure MIPS ELT F to make sure the valve is sealed This can be done by putting a small amount of saliva on the air valve and checking to see no bubbles are formed REMOVING SHOCK OIL Remove the shocks from the bike Depressurize the low pressure chamber This is the air valve at the large finned end of the shock Hold the shock upside down and push in the air valve to drain some of the shock oil Drain the oil into a small graduated cylinder or suitable measuring device Be careful to make sure that all the oil goes into the measuring device Reinstall the shocks on the bike and set the low pressure setting to the previous value ACCURATELY SETTING THE SHOCK AIR PRESSURE All your tuning of the shock air pressures can be difficult if you can t measure and adjust the air pressures accurately A normal air pressure gauge will not do the job At a minimum you need a t handle type schrader valve connector or zero loss air valve connector The connection to the air valve should not allow any air pressure release when you are trying to measure or adjust the pressure If you are using air in you shocks we recommend the FOX Racing Shox air pum
16. nstall the new bladder by fitting the open end up over the lip on the eyelet Place one SMALL drop of Red Loctite on the eyelet No more or No less Carefully slide the bladder into the shaft Tighten the eyelet to the shaft Finish rebuilding the shock by adding the shock oil and installing the shaft assembly into the body Refer to the page 10 in this guide for specific instructions MOTOXMUSEUM 2001 12 NO BLADDER AVAILABLE HERE IS WHAT YOU DO ene ene FIGURE 32 The Air Shox can be rebuilt and used even if the bladder is damaged and no replacement is available The result is a single spring rate shock compared to the Air Shox s original dual spring rate design The following is the recommended modifications when no replacement bladder is available Remove the bladder following the shock disassembly steps and bladder replacement instructions detailed earlier in this article Carefully cut the top off the bladder as shown in Figure 32 This removes the main part of the bladder but leaves the portion required to seal the lower eyelet to the shaft Reassemble the shock following the same instructions for replacing the bladder You will have to determine the bladder s displacement volume before you cut it This can be measured by putting some water into a graduated measuring device Record the volume of water in the device Then inserting the bladder open end up until it fills up Record the volume of water in the device
17. original Air Shox Gas Shock and Twin Clickers designed for Motocross applications Jeff and his crew are dirt bike enthusiasts and really give the extra effort to help any customer with current or out of production product A rebuild kit costs 28 00 FOX Racing Shox can rebuild a set of Air Shox parts and labor for 95 00 Twin Clickers can be rebuilt for 99 00 all prices in US FOX Racing Shox also sell it s own special shock oil for Air Shox Contact Service at FOX Racing Shox 130 Hanger Way Watsonville CA 95076 1 800 FOX SHOX J R S MACHINE JR Ott at J R s Machine Shop in Texas has almost 25 years of experience with the Air Shox JR has built the tooling required to build the high pressure bladders for all sizes of the Air Shox JR also sells seal kits and eyelet bushings for the Air Shoxs JR is a long time Vintage MX racer and a wonderful resource for anyone working on FOX Air Shoxs or Vintage MX bikes JR sells bladder kits for 42 00 seal kits for 35 00 shock eyelet bushings for 60 00 and a complete shock rebuild Parts and Labor for 150 00 all prices in USS Contact JR at J R s Machine Shop 838 North Dick Price Rd Kennedale Texas 76060 Tel 817 572 1025 e Fax 817 478 4307 WWW ELSINORE AU COM AUSTRALIA Geoff Bull sell rebuild kits and bladders Geoff s kit includes a newer design Moly impregnated seal and a super shaft bumper Geoff s kit also includes a set of reproduction second generation shock dec
18. p The small volume of the pump makes it easy to make small adjustments in the pressure The pump has a built in pressure gauge from 0 300 Psi a bleed valve and a zero loss schrader valve connection and it is very affordable Contact your local dealer or check www foxracingshox com See figure 33 If you are using Nitrogen you can try to locate one of the original FOX pressure gauges They were available in a hose style or handle style The hose style had a low pressure 0 60Psi Model for forks and a high pressure 0 200Psi model for the Air Shox REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 16 FIGURE 33 However the best choice and easily available today is Motion Pro s Nitrogen shock gauge and filler The gauge filler set is easy to use available from your local dealer and works well with gas shocks new and old Contact your local dealer or check out Motion Pro at www motionpro com FIGURE 32 oe TE If you notice when you come back to check the shock pressure it is always Lik lower than you set it remember that a specific volume of the air in the shock goes into the hose and pressure valve every time you measure the pressure Therefore it is always important to have documentation of what the air pressure was set to you can not come back and accurately measure it again MUSE REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 17 SOURCES FOR AIR SHOX PARTS AND SERVICE FOX RACING SHOX FOX Racing Shox still services the
19. pt disassembly with the shock pressurized FIGURE 3 F Mount the shock upside down in a vise using the top eyelet Use a set of jaw covers to protect the soft aluminum of the shock from being damaged by the vise Using a 2 inch wrench or a very hi quality adjustable wrench loosen the bearing housing from the upper shock body See Figure 3 re 7 It is possible for the eyelet to start to unthread from the shock body before the MUSEUM bearing housing starts to loosen If this happens tighten the eyelet and then carefully apply heat to the shock body around the bearing section This will help expand the shock body and loosen the threads on the bearing housing Remove the shaft assembly Clean out the inside of the shock body Pay careful attention that no small seal particles or other matter remain in the shock body Leave the shock body in a position to drain any fluids left inside Cover the opening in the shock body and place it aside for the assembly phase Te Remember that cleanliness is next to Godliness when working on any precision MLISELIM components such as the FOX Air Shox PISTON DISASSEMBLY Figure 4 shows the shaft assembly after removal from the body Carefully remove the piston ring from the piston Be very careful with the piston ring as there are no replacements available Remove the nut holding the piston assembly to the shaft Use care in holding the shaft still while removing the nut Any damage to the surface
20. seals when installing the bearing housing Install the top out bumper Install the new o ring on the bearing housing FIGURE 19 Install the top out plate and smaller shim washer on to the piston end of the shaft FIGURE 20 FIGURE 21 Install the large shim washer REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 8 Install the piston Note the FIGURE 22 correct orientation of the piston FIGURE 23 Install the check ball spring and washer FIGURE 24 Install the nut Carefully hold the washer in place to prevent the wrench from catching and distorting the washer while tightening the nut FIGURE 25 Install the piston ring FIGURE 26 Figure 26 shows the complete rebuild shaft assembly REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 FIGURE 27 Fill the shock body with the correct amount of shock oil Josef used the FOX Racing Shox s own special shock oil See page 21 Important Data for a table showing the amount of oil required for the various shock lengths Carefully insert the shaft assembly into the body Thread the bearing housing into the shock body by hand Tighten the bearing housing to the shock body using a 2 inch wrench or a hi quality adjustable wrench PRESSURIZING THE SHOCKS m MOSELA AGE The FOX Air Shox can be filled with air or Nitrogen While Nitrogen requires a special pressurized cylinder and regulator it does offer several advantages over air Nitrogen is an iner
21. sting the amount of oil in the shock TUNING THE SHOCK DAMPING The Air Shox damping is controlled by an opening in a jet and a pop off valve The jet is responsible for slow speed damping and the pop off valve is used for high speed damping Originally you could change the size of the hole in the jet and the strength of the pop off spring to modify the damping Today the pop off springs are no longer available Therefore only the low speed dampins characteristic can be changed To modify the low speed damping you will need to drill out the original jet or purchase a new jet from an automotive store The jet used is a standard Holly carburetor main jet It is recommended that you do not modify the original jet but purchase a new jet to modify See page 21 Important Data for a table showing the original jet hole size and the minimum and maximum recommended holes sizes na X EE Although the pop off springs are no longer available the same pop off spring VUSEUM UUL rate was not used on every size of shock Therefore it may be possible to use a set of pop off springs from a different size shock as the source for a different pop off spring See page 21 Important Data for a table showing the relative strength of the various springs used As well the table shows the recommended softer and harder spring numbers for each size of shock You may also want to try a different viscosity of shock oil to adjust the high speed damping and then chan
22. t gas and does not contain contaminants that will cause the shock oil to oxidize or cause the break down of the shocks rubber components This will result in a consistent shock performance and longer shock life Nitrogen also changes density less than air when it is heated up This results in less spring rate increase over the course of a long race If the expense of Nitrogen is outside your budget FOX Racing Shox makes a super air pump designed for their current bicycle air shox The pump includes a zero loss air valve connection built in air gauge up to 300 psi and a bleeder valve to adjust the pressure Definitely the tool to use if you go with air in your shocks See page 16 for more information Fully extend the shocks Orient the shocks the same way they will be installed on the bike large end of the shock at the top Set the high pressure first This is the lower air valve Then set the low pressure It is easier to over pressurize the shocks slightly and then adjust them to the required setting See page 19 Recommended FOX Air Shox Settings for the recommended pressure settings REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 10 REPLACING THE HIGH PRESSURE BLADDER meem UUE Replacing the high pressure bladder is not part of the standard shock maintenance or rebuild The bladder only needs to be replaced if it leaks oil when the bladder is depressurized FOX Racing Shox no longer makes bladders for the Air Shox However J R s Ma
23. the shock Check the shock parts for any physical damage While scrapes on the main body dont look nice they will not impair the shocks operation Inspect the eyelets and lower shaft for physical damage Figure 2 shows an example of shaft damage The shaft is pitted and rough While the shock can still be used the seals will wear out quickly Improperly installed shocks were prone to shaft damage from the drive chain If the shock eyelets main body or shaft have major physical damage stop here Replacement parts are not available for these components The only value the shocks have is as parts REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 1 FIGURE 2 san LE san LE te WO It is possible to fix some types of shaft damage Pro Action will grind the existing shaft to remove any pitting The shaft is then chromed plated to the original dimensions and finish As for the other parts it may be possible to have a local machine shop build you a new part but it will not be cheap After physically inspecting the external parts of the shocks its time to check if the high pressure bladder is okay Holding the shock with the large finned end up carefully depress the upper air valve to release the low pressure air It is normal if the air comes out oily or if oil spurts out the valve The upper low pressure chamber is an air oil emulsion Still holding the shock up right depress the lower air valve to release the high pressure chamber If oi
24. ver a rough section of the track normally ridden with the gas full on What s happening is the bike is squatting too much under acceleration and not enough travel is left to absorb the remaining bumps e A pressure too high will result in a ride that is overly stiff This can usually be felt over small bumps and in parts of the racetrack where the bike is not being accelerated HIGH PRESSURE GUIDELINES The high pressure setting only effects performance on sections of the race track where the shock is using most of the travel to absorb bumps This includes fast bumpy sections and landings off jumps Change the high pressure in steps of 10 Psi e A pressure too low will result in hard landings off jumps as the shock is bottoming out This can be verified by moving the bumper REBUILDING FOX AIR SHOX MOTOXMUSEUM 2001 14 up the shaft riding through the section and verify the shock is traveling the full stroke and bottoming out e A pressure too high will result in a rough ride and a shock that is possibly not delivering the full travel available Ensure that you are using all the shock travel by moving the bumper up the shaft Ride the track and verify the bumper is pushed back to the bottom of the shock un JE Le 100 It is also possible to adjust the spring characteristics of the shock by varying MUSEUM LU UL the amount of oil in the shock If the shock performance is optimal except for a couple of specific sections consider adju
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