Budget shock adjuster?

RustyC · Jan 29, 2017

I've been reading on Fox's new DSC adjusters. (http://accutuneoffroad.com/articles/how-fox-dsc-dual-speed-compression-adjusters-work/)
Great article from Accutune.

I am wondering exactly what happens inside the reservoir as oil pressure rises in the shock during compression. My understanding is that if the reservoir has 200 psi of nitrogen in it when the oil pressure reaches 200 psi the floating piston in the reservoir will begin to move compressing the nitrogen even more.
The DSC adjuster allows oil flow to be restricted to the reservoir. Being externally adjustable is HUGE for me as my tuning session are also my riding weekends. An external adjuster would allow me to make real time changes over a weekend without removing the shocks. Then back at home I can make valving adjustments to closer to the end goal.

Here is my biggest struggle. I have 2 rigs and own 8 coilovers. I can't justify adding the DSC adjusters to my shocks since they are FOX 2.0" and a 2.5" shocks are what I really desire.
I work with hydraulics on a weekly basis and did a little brainstorming and came up this the following.
(http://www.surpluscenter.com/Hydraulics/Hydraulic-Valves/Flow-Control-Valves/3-8-NPT-8-GPM-PRINCE-WFC-600-IN-LINE-FLOW-CONTROL-9-7960-6.axd)

I'm considering adding these to my buggy at the current reservoir. My thinking is it would give me adjustable from 0-100% flow to my reservoirs. Same basic principle of the Fox DSC adjuster for low speed adjustment but would not have the adjustable high speed relief of the shims. I would have to remove the shocks and adjust shims to tune that. There would be unrestricted flow on the rebound stroke allowing the floating piston in the reservoir to return.

There are several smart guys on this site and I would like to hear some opinion about this. :stir:

Forbanger · Jan 29, 2017

I have heard that these are only for fine tuning and make very lil noticeable difference. No real world experience.

BUG-E J · Jan 29, 2017

I have some coming in the next month or so. They are gonna be tuned with the knob "dead center" so I can fine tune it. I do more riding than racing so I run into the problem of my shocks are too soft to race and too stiff to leaf look. This is supposed to be my cure. After I get them I will let you know :dunno:

gottagofast · Jan 29, 2017

Afaik if it has 200 psi of nitrogen then it already has 200 psi oil pressure???

RustyC · Jan 29, 2017

gottagofast said:
Afaik if it has 200 psi of nitrogen then it already has 200 psi oil pressure???

Depends on if the floating piston in the reservoir is bottomed out prior to charging with nitrogen. I would think, but valid point.

gottagofast · Jan 29, 2017

Not certain but I think the only purpose of the floating piston is to keep the nitrogen from mixing with the oil.
Keeps it from foaming.

mac5005 · Jan 29, 2017

That's a very interesting thought.

The fox dsc is for dual speed adjustments, one for low speed events and one for high speed.

The trouble I see with flow control on just the resi hose,

If you get enough flow restriction to feel a difference at low speed, then that will be way too much restriction for high speed, possibly causing shock to hydro lock, or feel like it's bottoming, as the pressure in the shock would spike:

This would be identical to what happens in an air shock as it approaches full bump.

Not saying it won't work, just kicking the idea around.

The floating piston just separates the oil and n2 in the resi.

It also applies pressure to the oil to keep it from foaming.

The other thing is the ifp has to move to allow for the volume of oil in the resi to raise as the shock shaft takes up more volume in the shock itself during bump.

I'm not saying it won't work lol.

But if you get it on, and start tuning it, and hit a big bump and it feel super stiff all of a sudden, you know why.

My concerns with the flow control valve are based on the same principles as to how the Bleeds work in the piston.

Low speed, the oil can pass straight thru the bleeds. As soon as shaft speed increases, the oil stops going thru the bleeds, and forces the valve stack open.

With the flow control on the resi hose, there would be no "valve" to open as the piston speed increases.

I think it would work. Just don't know how well.

I say do it, and report back the effects.

mac5005 · Jan 29, 2017

Another thought,

If resi hose is too small, then that will "feel" like you can't get the compression light enough for high speed events.

It's will work fine at low speed and mid speed stuff, but for the high speed events, the valving will feel stiffer than it should.

This is all due to resi hose restriction.

TRD · Jan 29, 2017

Forbanger said:
I have heard that these are only for fine tuning and make very lil noticeable difference. No real world experience.

This is true if they are poorly designed. Not all compression adjusters are created equal and some brands are very bad. The Fox DSC Adjusters really do work! You'll probably use the low speed knob the most.

TRD · Jan 30, 2017

RustyC said:
I've been reading on Fox's new DSC adjusters. (http://accutuneoffroad.com/articles/how-fox-dsc-dual-speed-compression-adjusters-work/)
Great article from Accutune.

I am wondering exactly what happens inside the reservoir as oil pressure rises in the shock during compression. My understanding is that if the reservoir has 200 psi of nitrogen in it when the oil pressure reaches 200 psi the floating piston in the reservoir will begin to move compressing the nitrogen even more.
The DSC adjuster allows oil flow to be restricted to the reservoir. Being externally adjustable is HUGE for me as my tuning session are also my riding weekends. An external adjuster would allow me to make real time changes over a weekend without removing the shocks. Then back at home I can make valving adjustments to closer to the end goal.

Here is my biggest struggle. I have 2 rigs and own 8 coilovers. I can't justify adding the DSC adjusters to my shocks since they are FOX 2.0" and a 2.5" shocks are what I really desire.
I work with hydraulics on a weekly basis and did a little brainstorming and came up this the following.
(http://www.surpluscenter.com/Hydraulics/Hydraulic-Valves/Flow-Control-Valves/3-8-NPT-8-GPM-PRINCE-WFC-600-IN-LINE-FLOW-CONTROL-9-7960-6.axd)

I'm considering adding these to my buggy at the current reservoir. My thinking is it would give me adjustable from 0-100% flow to my reservoirs. Same basic principle of the Fox DSC adjuster for low speed adjustment but would not have the adjustable high speed relief of the shims. I would have to remove the shocks and adjust shims to tune that. There would be unrestricted flow on the rebound stroke allowing the floating piston in the reservoir to return.

There are several smart guys on this site and I would like to hear some opinion about this.

If you look at the DSC compression adjuster it has two flow paths. The free bleed for slow events and small bumps (g-outs, etc), and the deflective disks for high speed (hitting a rock). The flow controllers you posted are probably just a free bleed adjustment and won't flow enough oil on a big hit. Certainly worth a shot, but I wouldn't spend too much $$ up front.

RustyC · Feb 11, 2017

Well the shocks, adjusters and reservoirs are assembled and installed back onto the buggy. I performed my highly calibrated chassis roll test by hand, grabbing the a pillar and b pillar and shaking it side to side.
Fully open adjusters the body roll feels the same as without them installed. Full closed there is virtually no body roll and the shock feel very stiff. Seems to be a lot of room for adjustment between the two settings as well. So far so good. :dblthumb:

I won't get to test them further for a couple more weeks.

TRD · Feb 12, 2017

Very cool!! Looking forward to feedback.

RustyC · Mar 27, 2017

Finally was able to get the buggy out on the trails to see how things would work. I had reworked the rear shock mount and spring combonation to allow for 8" of uptravel on a 14 " shock with about 2.5" of spring preload 16"/14" spring lengths. I also lightened up the front spring combo as well. The 38" sx / H1 combo is heavy so I opened up the bleed holes in the rear and lightened the rebound stack to get them moving. Front rebound valving was lightened as well.
I spent 2 days on the trail and ran 15+ gallons of fuel through the engine to come up with this.
The rear felt very, very good compared to before. I did close off the oil flow using the adjuster by about 25% for about an hour. I could definitely feel a change in the stiffness of the rear on compression. I ended up opening the valves fully and was happy at that point. I plan to lighten the rear compression a little more and try again, hoping if I go too light I can dial things back in with the adjusters. I did jump the buggy a few times and I felt great without bottoming out hard. I actually notice my rear air bumps completely compressed and didn't rebound out (time for a rebuild).
The front feels not as good. Keep in mind I run the front tire over half full of water. Compression seems still and rebound too slow. Plans include revalving and more preload to get the axle to push back down.
I also noticed for the first time the front to hop a little at the exit of a turn with tiny ruts/whoops, chattered the front suspension a bit under heavy throttle. I think the water in the tires has a large effect on this.
I may reduce or remove the water in the front as well to get to where I want to be.

Overall the adjusters did work as planned, without negative4 effects on the rebound but I need to lightened things up to see how well they will work overall.

First time to ever jump anything too so this was cool for me.
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