What is your Fox 2.0 Valving on stock springs?

[mbh84]

I have searched and searched but most end up discussing Sulastic, aftermarket leafs, tire psi, etc. wanting to stick strictly to valving please.

I have an F-350 CCLB Dually(yes) air bags in the rear, stock springs and Fox 2.0 performance with reservoir on all corners. That I use to tow a 16k fifth wheel with. Valve code on the dust cap is T/90, which from what I’ve gathered is something like a (flutter compression)30/90(rebound). The issue I have is the truck will dip in slight hole and the compression is not fast enough on the coming out so it bounces out. Yes I’m aware “it’s a truck” but I believe I can make it better with a few changes. So I’m gonna re-valve, which any body that has tried will say it’s tough to get it right on the first try.

So of course call Fox and see what they say....... “the piston I have is a single bleed .070 and code was last updated in 2009. I should add .070 bleed to all pistons and change the compression side to #50 in the rear(to work in conjunction with the bags and change compression to #70 in the front......i could be wrong(hence why I’m here but)I would think increasing the stack thickness from the .008 to .012 would have the opposite effect of what I’m trying to achieve. Making compression stiffer. Hoping somebody has a similar setup(stock springs/aftermarket bags and 2in shocks) that wouldn’t mind taking a peak at their dust cap(where the shaft goes in and giving me some idea of what I should be going for.

Thanks




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[HeavyAssault]

I've been told more than once you want to allow compression and control the rebound. Make the spring work. I know it's all about personal preferences. Not to mention what PSI are your tires.

 

[mbh84]

I've been told more than once you want to allow compression and control the rebound. Make the spring work. I know it's all about personal preferences. Not to mention what PSI are your tires.

Thanks for the reply, I’ve tried dropping tire psi to 30, with the same results.


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[mbh84]

No one? Well I guess I’ll do some experimenting. I talked to Fox again today and there actually was a misunderstanding of what I was after. Said “Adding 2nd bleed port would allow a lot of low speed, we want to use compression to control it. So use a #50 stack(0.010) and keep the same flutter pivoting on a 0.008.” I have riden in the truck and know how it feels and what I believe it should feel like, can’t help but think increasing to a #50 stack would yield a similar performance to what I’ve got now...Being that it takes all of 15 mins to rebuild a shock I figured why not just toy around, see what I can come up with.

Got a few things to do tomorrow so want to leave this here in the hopes someone that knows will tell me “ hey you’re screwing up” or “yea looks legit”
Here’s what I’ve got so far.

Move my thinnest 1.42x.006 to front to allow more flex and flow
Move my 1.35x.008 to the second position for support
Leave the .8x.010 for pivot
Move my 1.6 to the 4th position to give the flow leverage in the high speed as well as support for the “front line” so to speak.


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[HeavyAssault]

For 15 mins of work even if it's not right sounds like an easy fix. Go at it Bro. You are blazing the trail.

 

[blackseven]

How did it work out? I have a similar issue with bouncing rear suspension on a CCLB Dually pulling a 15k 5th wheel Toyhauler and Rancho 9000's. Have been seriously considering moving to the Fox 2.0's.

 

[mbh84]

I changed the shims around to this configuration and drilled out the bleed hole in each piston(per Fox).....smoothed out a lil bit but I can’t stop there lol. still has a jitter in the rear end sometimes. seems to “float” better now the front wants to rock when turning slow up an incline. Not bad just more noticeable. Can’t seem to find anybody that’s happy with their setup and willing to get the valving numbers off their dust cap, so searching and searching some more. I did come across a dodge forum where Don Thuren from Thuren Fabrications set a dually up with 40/100 in the front and 20/120 in the rear but unsure of what dodge/spring rate/weight or how he stacked them. I wrote him on Facebook but he hasn’t responded.

In my mind I’m trying to imagine what that valving would feel like as I’m driving and it would make sense given the strength/stiffness of the springs to have really light compression(for give) and a heavy rebound(to resist the tires from slamming back down) as well as be different from front to back. So I may try it out, but since I’m new and not a lot of people are in the game of dually suspension or willing to give away their trade secrets gonna look into it some more before I just start throwing money at it.


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[mbh84]

How did it work out? I have a similar issue with bouncing rear suspension on a CCLB Dually pulling a 15k 5th wheel Toyhauler and Rancho 9000's. Have been seriously considering moving to the Fox 2.0's.

I’m sure if you were to get them from Carli, BDS(believe owned by Fox), even Thuren fabrication or anybody that does their own valving like a shop that has a way of weighing the front/rear the 2.0s can be valved to almost Cadillac status.

If I were looking to buy some more I’d call Carli or Thuren and see what they say your best options would be.


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[mbh84]

Ok after I’ve spent about a year trying to get my 13 f350 dually to ride better on 22” wheels and 34” tires I’m willing to put some of this out there on how to re-valve Fox 2.0 reservoir shocks and changing the bleed in the piston.
Plenty of videos on YouTube that explain the process better than I can. But it’s real easy to do. You can get your local 4x4 shop to refill the nitrogen if you don’t have the nitrogen bottle setup yourself.
I changed weight from a 7w to a 10w shock but not sure if it was needed.
Cheapest place I found to buy shims is Kar Tek a $1 a piece or stack for $6/5. For my .004 shims I bought .004 shim stock and turned them on a drill press(lil overkill but I got obsessed with it at one point)
If anybody wants to tackle it here’s what I did.

My pistons came with a single .70 bleed hole front/back. Front rode fine but it felt like it had too much body roll when hitting a bump/hole while turning into a driveway, so I went down a little. Filled it with JB weld(caped both ends well) and drilled another hole.

this pic of the shims isn’t what I ended up with but is a good way to keep up with changes as you go.

Diagram is....
Rebound
Piston
Compression

Front 27/98 give or take
—NUT
—-.8-.020
——.9-.015
———1.1-.015
————1.3-.010
—————1.4-.010
[a single 1/16 bleed]
[hole in the piston. ]
——————- 1.6-.006
—————1.4-.004
—- .8-.20
————1.3-.008
———-1.1-.008
——-.9-.008
—-.8-.020
——————-rate plate

Rear #20/97(?)
—NUT
——.8-.020
——-.9-.015
———1.1-.015
————1.3-.015
————-1.4-.015(x2)
[single 1/8 hole in the]
[piston for bleed ]
—————-1.6-.006
—————1.4-.004
—.8-.020
——1.1-.006
———-1.3-.006
——.9-.006
—.8-.020
—————rate plate


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[BIG JUICE]

Results are? I really think the 3"kings are coming soon on my truck. I like these 2.0 fox with Carli valving but I feel like it could be much better also. I haven't got to the point you have to bother with it. My 2.5" kings on my excursion had more plush ride with better control than I have now

But that was a leaf spring truck and I hate to try to compare the two

 

[mbh84]

It is a whole different ride. I highly suggest before you spend the cash on a new set give it a shot. The biggest difference comes from changing the bleed.
At first I was having it shake/jitter in the rear after the slightest imperfection in the road (such as a recessed sewer cap) so I closed off the bleed in the rear shocks, thinking is needed more resistance...bad idea rode worse. Come to find out the jitter was coming from a bad wear band. I noticed only because I had accidentally swapped it when I had them both opened and after putting them back together noticed it coming from the opposite side and that was the only thing different, from one side to the other.

If you have too much bleed or not enough compression dampening up front it will feel loose and hard to control. You can add more free bleed in the rear(which I recommend)to counter it, and it will actually put more control up front and/or go down a drill bit size or 2.

I just finished adding another 1/16 bleed hole in the rear because I felt my compression stack coming into play a little earlier than the front and would pitch the rear up coming out of slow dips and smooth bumps. Small test drive felt a lil plusher although it had some hard spikes on what seemed like a smooth road but I like to give it a few days to really get a feel of how it’s working. May open it up the rear bleed a little more.

I’m not sure if it makes a difference having 2 of the same size bleed holes vs having one larger than the other. My thinking(could be wrong here) is it’s like pipe you get more velocity from a 4” pipe compared to 2 2” pipes. Something to do with less drag from pipe surface. Being these shocks are velocity sensitive I figured I’d get the best flow from the larger hole. So in the rear right now I have a total bleed of .1719 going by the yellow chart above.


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[PDT1081]

I’m not sure if it makes a difference having 2 of the same size bleed holes vs having one larger than the other. My thinking(could be wrong here) is it’s like pipe you get more velocity from a 4” pipe compared to 2 2” pipes. Something to do with less drag from pipe surface. Being these shocks are velocity sensitive I figured I’d get the best flow from the larger hole. So in the rear right now I have a total bleed of .1719 going by the yellow chart above.


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Cross sectional area of a 4 inch pipe is 12.56 square inches. The 2 inch pipe is 3.14 inches. Need roughly 4, 2 inch pipes to equal a 4 inch pipe. The pipe surface area causes friction, and the 4, 2 inch pipes have more than the 1, 4 inch pipe. I'm fairly confident the friction in regards to the bleed holes can be disregarded.

 

[mbh84]

Cross sectional area of a 4 inch pipe is 12.56 square inches. The 2 inch pipe is 3.14 inches. Need roughly 4, 2 inch pipes to equal a 4 inch pipe. The pipe surface area causes friction, and the 4, 2 inch pipes have more than the 1, 4 inch pipe. I'm fairly confident the friction in regards to the bleed holes can be disregarded.

Thanks, you obviously know the subject well but just to dig a lil deeper you’re saying 2 would choke off quicker than a single that’s double the size?

Not so much concerned about the friction, instead I’m considering choking off as in you’re going 70 MPH and hit a 2” bump, the piston inside the shock will move 2” in a split second, I don’t have time to do the math but just say that it moves at 4” a second(smooth bump). Being that you mainly feel the the bumps that cause the shim stacks to flex, I prefer the fluid be able to pass through say a water hose(slow smooth) vs say 2 fuel lines(jet stream) to keep the shock fluid cool without any cavitation and shim stack still. Of course this analogy is subjective, just painting a picture.


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[PDT1081]

Thanks, you obviously know the subject well but just to dig a lil deeper you’re saying 2 would choke off quicker than a single that’s double the size?

When you're figuring your hole sizes for flow, you need to know the cross-sectional area (πr^2) to accurately add them together. An 1/8 inch hole plus a 1/16 inch hole doesn't equal one 3/16 inch hole.

Going back to your 4 inch pipe example: When you put 2, 2 inch pipes side by side you don't end up with a 4 inch by 4 inch hole. You end up with a hole that is 4 inches wide, and 2 inches tall (roughly).

Not so much concerned about the friction, instead I’m considering choking off as in you’re going 70 MPH and hit a 2” bump, the piston inside the shock will move 2” in a split second, I don’t have time to do the math but just say that it moves at 4” a second(smooth bump). Being that you mainly feel the the bumps that cause the shim stacks to flex, I prefer the fluid be able to pass through say a water hose(slow smooth) vs say 2 fuel lines(jet stream) to keep the shock fluid cool without any cavitation and shim stack still. Of course this analogy is subjective, just painting a picture.


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What you're getting at here is far above my education level to be able to explain, especially in writing. I understand exactly what you're saying. I just don't know how small the hole has to be before you need to worry about it.