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Discussion Starter · #1 · (Edited)
This is a shock tech thread to show the internals of a shock, how to change the valving and some general information. These are Fox DSC shocks here and I can go thru others as needed. I believe Fox is one of the best shocks on the market and its what I've had my hands on the most in the SxS world.
A little background to add a little credit to things. I own a off road shop in North Carolina. I specialize newer Jeeps, Ultra 4 cars, suspension tuning 95% on solid axle vehicles and a little SxS work for friends. I personally race my stock width Teryx in a local series out here called ECORS and I'm a podium finisher every race, what I do works. I have to work my shocks to keep up and beat XP's and Wildcat's. Ill be running Rally Raid all next year for a total of about 16 races. I'm not doing this for business sake, I have zero plans on being a vendor on here and getting in the SxS market. It just so happens that my experience with the bigger stuff trickles down in the SxS world a little. This is just to help.....hopefully


Here are a couple vehicles I do work on.
A customer of mine, 600hp Ultra 4 car



The JK I put on the cover of Crawl Magazine in November of 2010



The same JK we race ECORS in



The Teryx in the air

 

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Discussion Starter · #2 · (Edited)
These are tools you need to get the job done. Dial caliper, 90 degree pick, 3/32 allen wrench, large channel locks, 19mm wrench, nitrogen tank with regulator, and shims. Having some shock oil around is a good thing as well.



With the shock clamped in the vise and the nitrogen released loosen the 3/32 set screw but don't remove it, one full turn is fine. Then grab the big pliers and a rag (I have a spanner wrench for this but what to show it with common tools), with the rag and pliers on the knurled seal cap break it loose and spin it off by hand

 

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Discussion Starter · #3 · (Edited)
This is the bearing housing, it holds all the major seals and has a bronze bushing for the shaft that keeps it centered and true. If you have a leak its because the seals and o rings on this piece below are bad. The black seal cap that gets loosened with pliers is there just to keep stuff out, it doesn't keep anything in.



MAKE SURE THERE IS NO NITROGEN IN THE SHOCK. Push the bearing house down till the snap ring is visible, grab the pick and remove the snap ring.



With the snap ring out pull up on the shock shaft and remove the assembly, try to keep as much oil in the shock as you can.

 

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Discussion Starter · #4 · (Edited)
So whats happening is as the piston moves through the fluid its bending these shims up to allow fluid through the ports. Several things control the way the shock reacts but mostly the size and thickness of the shims do it.

Rebound side of the piston



Compression side of the piston



Grab the 19mm or 3/4 wrench and remove the nut.

 

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Discussion Starter · #5 · (Edited)
Compression side of the piston. Note the tiny hole in the top of the piston. That's a bleed hole which is uncommon in Fox's UTV shocks, Ill get into bleed later.



The top is the rebound stack and the bottom is the compression. This is a crazy amount of valving for normal use and will pretty much beat you to death. This was a military shock setup so it was build for that application.



Shock shaft is empty, the washer can be removed and wiped down

 

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Discussion Starter · #6 · (Edited)
On the right is the smallest shim on the rebound side, on the left is the washer for the nut. The shim measures .800 in diameter and the washer measures .825, I generally don't put that shim in, esp in Kings. I use the washer as the fulcrum.



This is our new valve stacks for the REAR SHOCKS. Since this piston has a bleed hole I'm adding a extra .010 shim in. If it didn't have a bleed hole I would not add the .010's in. This is a basic progressive shim stack. The compression is bumped up a small amount over stock and the rebound is right about where Fox puts them from the factory. Shims or valves come in several different thickness's, .006, .008, .010, .012, .015 and .020 are common and we use these different thickness to get our desired ride but you have to know what changes do what. We can do several things to change the way the shock reacts. If we lighten the bigger shims, what I call the ceiling shims, and make the smaller ones thicker we can make the stack much more progressive meaning we can have it soak up the chop a little better but be firm on big hits. Another way to do this is to work with the bleed holes. Bleed is generally considered slow speed compression tuning, it has a extremely progressive curve on a shock dyno and at a certain shaft speed bleed doesn't contribute to the dampening. Things that aren't enough force to open the valve stack kinda. With these shocks only having roughly 5.25" of travel its hard to tune for bleed cause the travel simply isn't there and bleed can still effect things like body roll in quick turns or jerks of the wheel. I'm sure it can be done to make a better ride but it would take a lot of trial and error and I don't have to time in SxS shocks to try it and know 100% what its going to do. Another valve stack is the flutter stack, this should only be would for compression, never rebound. This would be the same as building a very progressive stack but it would be much more exaggerated. To do that you would put a small .800 or .950 shim under the ceiling shim or first two ceiling shims and use the small shim as a fulcrum. As the ceiling shims deflect they would bend past the fulcrum contacting the remaining shims and stiffening up. Again this is another way to absorb chop while also absorbing big hits. The front of the Ultra 4 car above has a flutter stack in it and it works very well but they have their place and its only in single shock applications, you would never use it with a bypass. Chances are if you see a single shock sand car or baja car it probably has a flutter in it. A flutter stack in these shocks probably would be a good idea, if you had a long travel car with upright shocks with towers you would have a better chance of getting it dialed in properly. Digressive stacks are something that don't work too well in the go fast offroad world for compression, the shock curve would be flat, Im not going to spend much time explaining this but they would work well for rebound but not compresion. When i install a LSR +3 kit on my Teryx this winter I'm going to work with a digressive rebound stack and a fluttered compression stack, but it'll be a pain in the ass to dial in.



This is what our new rebound stack looks like assembled

 

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Discussion Starter · #7 · (Edited)
This is our new valve stack assembled on the compression side. Notice the changes of the shims it came with



I left a couple pictures out but you want to bump the res with nitrogen and bottom out the IFP to make sure all the air is out of the shock. Then install the shaft assembly back into the body. Bump the end of the shaft to shock the valves so you can bleed the air out of the system. This is critical, you must get all the air out of the system, since this shock has a bleed hole its a little easier. Push the bearing housing in to where the fluid just starts to come out before the o-ring on the bearing housing gets to the body of the shock. This is how we get the last little bit of air out. To raise the fluid level push the shock shaft in or add more oil. Be patient, I've done this a lot so I know at what point the fluid needs to be at in the body.



Install the snap ring and to seat the bearing housing fill the shock to 150psi, for a race shock we would run 200-250 on a top mounted res.

 

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Discussion Starter · #8 · (Edited)
Bring the seal cap down, snug it up with the pliers and tighten the 3/32 set screw.



There's about $2000 worth of shims and shock parts for Fox's, King's, SAW's, Profender's and Radflo's in my box. This can be a costly thing to do yourself and may be worth sending to someone to have them do it for you, there's a lot of awesome shock tuners out there.



Hopefully this helps some people and is something to reference in the future. I didn't cover everything, that would be darn near impossible and I can't share everything but things will apply differently to every application. Some things will work, some won't so don't get too caught up in what I put and think only one thing will work for you.
Alex
 

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shunky
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:icon_thumleft:WOW GREAT INFO! Those are some nice looking shocks btw...:rofl2:
 
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Thanks alot man now I want new shocks lol
 

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Cool write up.
 

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El Moderator
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"A" for the day...to me shock guys are like engine tuners, a lot of guys can do it, but not many do it well

transcribed by carrier pigeon for Tapatalk
 
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Discussion Starter · #14 · (Edited)
My stock travel shocks will be for sale this winter when I change suspensions

Picking the right springs for your shocks is just as important, it needs to be a working combination. I like to run a lighter spring with heavy valving but it is much less forgiving than a heavy spring with the lighter valving so your valving needs to be right.
People like Eibach and PAC have charts for the springs they sell that tell all the numbers needed to get the right spring setup. By talking the length of the spring at at full extension with no weight or preload on it (in this case probably 10) and measuring the amount it compresses you can tell how much weight is on each spring. Remember its not a 1:1 suspension so the number you are going to get will be high. Take the amount it compressed in inches and multiply it by the spring weight and that will give you the weight put on each shocks so you can get your springs dialed in. Easy back calculating which some spring charts in front of you and you can probably get the right springs on the first try. You want as keep it as light as possible without coil binding. With a longer shock I like to run a dual rated spring. That way you can run a lighter spring and moderate valving and then when the shock hits the dual rate stop it jumps the spring rate up, sometimes as much as 3x the combined rate for hard hits or jumps.
 

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shunky
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Reed I have the shocks that you revalved and setup for me back on the rex. This thing rides a100% better. Where I used to have to go 20mph thru rough trails I can now go around 50mph. Your setup made a huge difference and made these shocks work like a charm. I can't believe how well this rex absorbs the rugged terrain. Thank-you. you did an excellent job!
 
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Discussion Starter · #16 ·
I pulled my shocks apart today and this is what the external rebound adjustment looks like. Is a one way valve adjusted by a metering rod



Race piston with no bleed



My front setup



I went ahead and tore them down and started on a flutter stack for the compression side. In the parking lot they are definitely softer with the flutter but hopefully they firm up tremendously on the hard hits. Ill make some adjustments as it goes and report back. Once this gets nailed down it will be darn near impossible to beat ride and performance wise.

 

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Areed, I like your style. My family successfully raced limited class offroad cars in California and Nevada for years. Tuning suspension is key but, as you said, it must also be tuned to driving stye.
 

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Discussion Starter · #19 ·
I believe after many runs and revalves I have found the perfect valving for a Fox shock on a stock width Teryx. Minor changes and it would work on a +3 as well. If you're interested in knowing let me know!
Alex
 
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