Fox Shox 101

[Punchdrunk Monkey]

I bought a pair of used Fox 2.0x10" shocks for the front of my car. The valving on Fox shocks is usually etched in the bottom cap of the shock (under the snubber). My shocks did not have the vavling noted. So before I put my front end together I wanted to know the vavling so I can make adjustments as required. I figured this would be a good time to take a few pictures and show those of you who have never seen the inside of a shock.

DISCLAIMER- I am by no means a shock expert. I know just enough to get my shocks apart and back together (hopefully without extra parts).

First release the nitrogen from the shock. Then place the shock in a vise upside down.


Loosen set screw on bottom cap. Unscrew cap. Rescrew on cap a few threads. Ever-so-lovingly, tap on cap with mallet. This will free up the piston in the shock. Now unthread the cap and slide up the shaft. Push down on the piston and you'll see a clip. Remove clip. Now slowly remove the shaft/piston from the shock body. Let the oil drain back into body.



Now you can see the shock piston and valve shims. There is also a teflon ring around the piston.

Take the nut off the the end of the shaft and remove all shims. I lay them on a clean rag in the order they came off the shaft. Compression is on the bottom of the piston and rebound is on top. I meassured each shim, both thickness and diameter, and noted them. Then refer to your handy Fox Shox cheat sheet (available on thier website) for valving. Ends up I have 50/50.





Now repeat the process in reverse and reassemble your shock. And don't spill the oil.
So now once I have the car running I can make adjustments as necessary based off of this info.

[rickosuave1987]

Thanks for the write up PDM...

Are you planning on changing your valving now? Or waiting to see how it rides?

My front shocks (which are identical to yours) work pretty well with 50/50 valving...

[david58]

This needs to be added to the stickie on shocks.
http://www.shoptalkforums.com/viewtopic.php?t=117191

[CopperBaja]

Thanks for the info! Hopefully I'll get a killer deal like you did and be able to put this thread to good use!

[rickosuave1987]

This needs to be added to the stickie on shocks.
http://www.shoptalkforums.com/viewtopic.php?t=117191

Done

[david58]

This needs to be added to the stickie on shocks.
http://www.shoptalkforums.com/viewtopic.php?t=117191

Done

I owe ya a cookie.

[Punchdrunk Monkey]

If I knew it was going to be a sticky, I would of used spell check.

[ntsqd]

Since this became a sticky it may be an appropriate place to mention a couple things?

Rather than grabbing the mount bearing in a vice what I was taught to do is to drill a shock body sized hole in a 2x4 or 2x6 at one end, and then cut a slot from the end into the hole. Clamp that in the vice, and then clamp the shock body in the hole with a C-Clamp.

Recently Redline Synthetic Lubricants has introduced shock fluids. This might make getting replacement shock fluid easier for those not in the So. CA area where there are shops that work on these things and carry the various parts. Summit caries Redline Product, though they probably do not have the damper fluids on the shelf. Look up the p/n on the Redline site and enter it into the Summit site to get price & delivery.
From what I've been able to piece together, most of the damper mfg's (King, Fox, Bils, etc.) use a 5 wt. fluid.
I have also used dirt bike shock (not Fork) fluid with good, though so far short term, results. Fork fluid isn't designed for as high of an operating temperature.

When you do the re-assembly you want to be certain that you have worked out all of the air bubbles from the fluid. Insert the piston into the shock body very slowly and with working it, slowly, in and out to work the air bubbles out from under the piston.
To get the last air bubble out of the shock, the one that will sit between the top of the fluid and the underside of the rod guide/seal, I have had to slightly over-fill the shock body (or bump the reservoir dividing piston to raise the fluid level in the body) and let the excess flow out and drip down into the pile of rags strategically placed on the floor. Most of the rod guide/seals have a groove or some other feature on the side to bleed this last little bit of air out. Ideally you were pushing a solid stream of fluid out just before the sealing o-ring contacted the shock body.
If there is a better way to do this I'd sure like to hear about it.

[Motochris]

One more thing....if you have a shock with a reservoir, be SURE to doublecheck the floating piston depth. If you don't, in most cases..when you put the shock back together, the piston will be moved slightly (or alot depending upon how ham-fisted you are) towards the air end of the reservoir. Do that enough times and the piston will smack the other end of the reservoir when in use and do all kinds of damage.

The correct way to check reservoir piston depth is to pull the schrader end cap off and measure the depth before reassembly. Each manufacturer has a spec for how deep it should be in there.
I cheat in the field and just pull the valve out of the schrader and I have a rod that goes thru it that's marked for the correct depth. If I hit the piston before it's to the right mark....I just keep pushing until it goes down to the depth needed.

Here's a pic of the end of a res. where the piston has gone too deep. See the "ballooning" affect and the tweeked end cap?

[vin]

so there is basically a floating divider between the oil and nitrogen? when you charge the shock with the nitrogen wont that push the divider all the way till it contacts the fluid?

[Punchdrunk Monkey]

My shock is an emulsion shock, the nitrogen and oil are mixed.

Motochris is refering to a remote reservoir shock.

[Motochris]

so there is basically a floating divider between the oil and nitrogen? when you charge the shock with the nitrogen wont that push the divider all the way till it contacts the fluid?

Yes, there's a piston that divides the air/oil to keep them from mixing. The piston is always in contact with the oil and moves with the oil level as the shaft goes in and out. If there was a pocket of air between it and the oil...pressurizing the reservoir still wouldn't push the piston into the oil, just compress the air on that pocket. There should be NO air in the oil on a reservoir shock. It degrades the performance.

[vin]

ok...i dont understand how you got the ballooning on that reservoir pic? i that from the floating piston? was there too much oil? is that why you check the floating piston depth, to make sure your oil level is correct?

[ntsqd]

ok...i dont understand how you got the ballooning on that reservoir pic? i that from the floating piston? was there too much oil? is that why you check the floating piston depth, to make sure your oil level is correct?

The floating piston moves because the as the shock compresses the shaft displaces it's volume of oil into the reservoir. If there is too much oil then the floating piston will hit the end of the reservoir when the shock approaches full compression. Liquids are essentially incompressible, increasing their pressure does not change their volume like doing so will with a gas.

If there is still some travel left in the shock when the floating piston can't move any further the pressure will go through the roof and balloon what ever is the weakest part or blow past the weakest seal.