Rebuilding Fox 2.0 Shock

luthj

Engineer In Residence
Greetings,

Many van owners have discovered the improved ride offered by the Fox 2.0 series shocks over many OEM and aftermarket options. I had a hard time finding a good photo essay of a 2.0 rebuild, so here goes.

Recently one of my rears blew a seal. Its been seeping slightly for about 18 months. Its had about 80k miles of abuse over multiple continents, so it doesn't owe me anything! Now I have adjustable external reservoir units, so they are a bit pricey. I decided to do a rebuild myself, and many of the steps will apply to emulsion and non-adjustable units.

The guide I am using is attached.

Here is the unit in-situ. Once the seal blew, it leaked until the IFP bottomed out, so about 200ml of shock oil.

IMG_20190420_104539448_HDR by J Luth, on Flickr

The first step is to thoroughly clean the exterior of the shock. Use a pick to remove crud from the reservoir end caps, and the groove around the bearing end cap ( black thing around the shaft).

IMG_20190423_131626312_HDR by J Luth, on Flickr


Here is the kit I am using. It was about 15$. There are a couple versions depending on the shock model.
IMG_20190423_131632327_HDR by J Luth, on Flickr


Next we release the gas charge. This screw has a small hole down the middle. Loosen it about 1 turn, then use an inflation needle to release the gas. I found this a bit tricky, so I gradually loosened it until it started leaking, then used the needle to get the last bit. Don't remove it completely, otherwise the screw and valve will rocket across the room (and get lost!)

IMG_20190423_132622105_HDR by J Luth, on Flickr


Next separate the cap/wiper seal from the body. There is a special tool for this, but some rubber pliers and a mallet (rubber vise jaws etc) works. My shocks are already banged up, so I just used a screwdriver with gently tapping.

IMG_20190423_133123806_HDR by J Luth, on Flickr

There will be some crud under it. Clean as best you can.

IMG_20190423_133149715_HDR by J Luth, on Flickr

To remove the bearing/seal carrier, you need to press it inwards about 1/4". If you have pressure in the shock it may rebound. I used a rubber mallet and a wooden down to free it up. Once pressed down you can see the snap ring. Pry it out with a pick, don't scratch the sealing surface farther down!

IMG_20190423_133152569 by J Luth, on Flickr

IMG_20190423_133218300 by J Luth, on Flickr

IMG_20190423_133834597_HDR by J Luth, on Flickr

With the snap ring removed, and any debris cleaned out, pull the bearing/shaft from the body. Spray some lube into the bore to make the O-ring slide over the groove easier. Put the shock in a vise (or between your legs) and pull/yank while rocking back/forth a bit. Avoid hitting the shaft with anything, you may damage the bearing. There will be a lot of oil, so be prepared for it to gush out when it finally comes free.
 

Attachments

  • FOX-Rebuild-Instructions-2.0-Performance-Series-Remote-Reservoir.pdf
    141.8 KB · Views: 216

luthj

Engineer In Residence
On the shaft is the valve stack, bearing/seal carrier, and bearing cap/wiper seal. The brown ring is the wear band which seals the valve casting to the bore. It goes around the valve casting ring (between the shims). There is a small O-ring beneath it.

IMG_20190423_134745002_HDR by J Luth, on Flickr

IMG_20190423_134748252_HDR by J Luth, on Flickr

IMG_20190423_134849975 by J Luth, on Flickr

Now to remove the reservoir caps. Start with the fill port end. Both remove the same manner as the bearing carrier. Again, clear the gunk from the ring grooves as you go. Use lube for removal.

IMG_20190423_135151788 by J Luth, on Flickr

IMG_20190423_135542618 by J Luth, on Flickr

Tap out the internal floating piston (IFP). Make a note of its position.
IMG_20190423_135639244 by J Luth, on Flickr

IMG_20190423_135716971 by J Luth, on Flickr
 

luthj

Engineer In Residence
As you go along, check for damage, cracks, etc.

Now on to the shaft seals. To get to them, the valve stack must be removed. I held the eyelet with some pliers, and hit the nut with an electric impact. Make notes on the assembly order!!! There are many thin shims that must be put back in the same order. The valve casting with the ports and wear band has a specific direction as well. On the bottom side, my largest shim had holes, and was not symmetric circularly. It has a single tab which must be aligned with the valve casting. Thankfully there was obvious witness marks to show where it needed to go. However I needed to scribe the casting to find the alignment when assembled.

IMG_20190423_135853707 by J Luth, on Flickr

Here is the bearing carrier and primary shaft seal. Note the rubber bumper, and the orange coating. Do not scratch the orange coating!!! Farther back you can see two seals. The first is an O-ring, and second a wiper seal. Use a pick and remove both carefully. There are two wiper seals in the kit, one goes in the black cap, the other in the carrier.

IMG_20190423_140538165 by J Luth, on Flickr

IMG_20190423_141257094 by J Luth, on Flickr

Take a moment to inspect the shaft. Make sure its straight and not pitted. I found the likely source of my seal failure (all other shocks are fine). A deep chip in the hard coating. It had an obvious catch with a fingernail. I carefully smoothed it with some 300 grit, and polished with 1000 grit. It should last a few years until I can replace the shaft.

IMG_20190423_141716109 by J Luth, on Flickr

There are O-rings all over the shock, so remove and replace as you come across them. Just match to the kit.

This is where I leave off for the time being. I have some oil on order. You don't need the fox brand oil. Any 5WT motorcycle fork oil will work. 5WT hydraulic oil may work as well (ISO 22?). But it can be hard to find.
 

b dkw1

Observer

luthj

Engineer In Residence
Yeah, I did a poor man's viscosity test with a orifice and stopwatch. The replacement oil is within 15% of the removed oil. I will be doing the other rear at some point, so it will get the same oil. Where do you source a compatible schrader unit?
 
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luthj

Engineer In Residence


Yeah, thats the conclusion I came too. I did see a site selling custom units for fox shocks. 5 different thread types, including 5/16 straight o-ring. they were 30$ each or so. Not worth it, I have a tap and drill, so its 3$ for a 1/8mpt schrader.

Edit, I see this one, and it should fit I think? Its a nice unit.

https://www.kartek.com/parts/fox-sh...-newer-fox-shocks-that-use-516-32-o-ring.html
 
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luthj

Engineer In Residence
I got my oil in the other day. I poked a small hole in the bottom of a plastic cup, and timed 250ml draining. They were within 15% of each other (new vs old), good enough for me.

First up I used some epoxy to patch the pit on the shaft. Polished it down with 1000 grit.

IMG_20190425_202407445 by J Luth, on Flickr


I set the IFP in the reservoir. The cupped side goes towards the hose end. Start with the IFP all the way towards the fill end. Lube the IFP with oil or a light grease.

IMG_20190425_202417346 by J Luth, on Flickr

Fill it almost to the top with oil, then insert the reservoir cap. Obviously the shock body needs held upright. With the hose side up on the reservoir, press the IFP in until it bottoms. This forces the fluid into the shock body, and purges any air in the line/cap.

IMG_20190425_203143304 by J Luth, on Flickr


Now top the shock body off with oil, stop about 2" from the top.

IMG_20190425_203451078 by J Luth, on Flickr

Insert the valve stack into the body. I don't show the wear band here, but it wraps around the groove and O-ring.

IMG_20190425_203530126 by J Luth, on Flickr

Slowly work the shaft up and down a few inches. Do not pull the shaft into the air. You want to purge any air trapped in the valve stack. If you push down hard enough, the IFP can move outwards in the reservoir. Push it back into place. Basically you want it bottomed out.

IMG_20190425_204102134 by J Luth, on Flickr


Top the shock oil to about 1/4" from the top. You will need to make sure the shock is fully vertical. Then insert the bearing into the body. Air will bleed out of the spiral groove until the O-ring seals the body. Continue to push the bearing down until you can install the clip. This will move the IFP about 1-1.5" from the hose end. This is normal.

IMG_20190425_204132200 by J Luth, on Flickr

Put the bearing cap on. Tap it with a soft mallet until it snaps in and seats flush all the way around. Install the reservoir fill cap.

IMG_20190425_204652678 by J Luth, on Flickr

Work the shaft through its full range to make sure everything is kosher. If you pull the shaft out quickly, the hose reservoir cap may move inwards a bit. It will reseat when the nitrogen is added.

At this point you are ready to pressurize. Use a small needle, or replace with a schrader unit. The thread is 5/16, and it needs an o-ring to seal.

IMG_20190425_205020141 by J Luth, on Flickr
 

luthj

Engineer In Residence
Attached is the fox 2.0 valving table. You can purchase valve shim kits, and adjust the valves damping as desired. I have also attached the valve table and rebuilt instructions for 2.5 and 3.0 shocks. The 2.5 rebuild process is basically the same, except they use a screw-on bearing cap, and the bearing is retained with a snap ring instead of circlip.
 

Attachments

  • fox-20-rebound-and-compression-shock-valving-shim-chart.pdf
    1.3 MB · Views: 148
  • Fox 2.5 rebuild instructions and valving.pdf
    2.3 MB · Views: 120
  • fox-25-rebound-and-compression-shock-valving-shim-chart.pdf
    1.3 MB · Views: 87

Ruby_Red

New member
Great information. Thanks!
i have Fox 2.0 Performance Series shocks on my 6” lifted Jeep JK. Mine do not have the remote reservoir, though. The shocks are still good, but maybe too good for my use. Unfortunately, we spend 90% of the time on streets and highways. I am wanting to reduce the amount of force required for the shocks to work, to make the ride ’softer’ on roads.
Would most of your information still be the same with my shocks?
Can I remove some of the springs washers to make the ride softer?
Still learning about these shocks. There is no place externally to add nitrogen, so what gives the shock pressure?
I have not seen one of these taken apart, so I am just not sure what I will find.
Any info on this would be greatly appreciated.
 

b dkw1

Observer
Great information. Thanks!
i have Fox 2.0 Performance Series shocks on my 6” lifted Jeep JK. Mine do not have the remote reservoir, though. The shocks are still good, but maybe too good for my use. Unfortunately, we spend 90% of the time on streets and highways. I am wanting to reduce the amount of force required for the shocks to work, to make the ride ’softer’ on roads.
Would most of your information still be the same with my shocks?
Can I remove some of the springs washers to make the ride softer?
Still learning about these shocks. There is no place externally to add nitrogen, so what gives the shock pressure?
I have not seen one of these taken apart, so I am just not sure what I will find.
Any info on this would be greatly appreciated.

What you need is to open up a bleed hole. This will stop the small stuff from transferring to the chassis and still have valving for the big hits.

Also, these shocks are not to much for what you are doing. They have a lot of adjustment which cheaper units do not.
 

Pentacleus

New member
Hi Luthj - You did a fantastic job with the right-up and photos. Thanks much. I am curious what oil you used, how much fluid did it take per shock (OR for all 4 shocks), and if you are happy with the oil you chose. Thank you much! - Josh
 

Brianj5600

Member
Wow, the depth of knowledge on this site vast. I have been tinkering on some Fox 2.0 remote reservoirs for the rear of my Jeep. I bought them from a place that does custom valving and they missed terribly. The pistons were drilled 2 bleeds with a #59 bit and that seems too much. It seems to oscillate on some stretches of road. Does that sound like a too much? Can I fill the bleeds and redrill smaller?
 

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