Fox 2.0 air shock setup
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Fox 2.0 air shock setup
I'm trying to figure out the best way to setup this suspension. It's a classic old school vw/sandrail frame like a chenowith or something. No unusual weight added just the engine/trans, gas tank and frame (type 4 engine). So I'm guessing I have about 225 lbs of weight per rear tire . The IRS rear end is from a Porsche 928 with the aluminum trailing arms. It has torsion springs , adjustable dampening shocks (rancho 9000) and long travel fox 2.0 air shocks. My thought was to set the torsions as soft as possible (basically they are there as a limp home shock in case I blow an air shock) and let the air shocks do all the work. I haven't a clue what types of loads (in lbs.) that the suspension would see under use. Should I calculate my nitrogen charge based on standing corner weight or weight under load or just set the ride height and call it good? Still gotta figure out oil as well. Any help would be greatly appreciated. Thank you.
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Re: Fox 2.0 air shock setup
Question: (I'm not trying to go on a tirade over this) when you say "air shocks" there are at least two types of shock that use this handle.
There are the gas filled shocks which are good and then there are the shocks that you can air to to lift or support the springs (https://www.bing.com/search?q=air+shock ... b1a98cf6eb) which were designed to be more of an overload shocks (I was warned when I got my first pair to be very, very careful not good to use them for so many reasons) or could be considered similar to air bags. My blue buggy had them when I got it and being not familiar to anything VW at the time they were installed by the PO to get the body and the rear tires away from each other. I almost flipped it end for end coming down one dune. I still occasionally see them used.
Lee
There are the gas filled shocks which are good and then there are the shocks that you can air to to lift or support the springs (https://www.bing.com/search?q=air+shock ... b1a98cf6eb) which were designed to be more of an overload shocks (I was warned when I got my first pair to be very, very careful not good to use them for so many reasons) or could be considered similar to air bags. My blue buggy had them when I got it and being not familiar to anything VW at the time they were installed by the PO to get the body and the rear tires away from each other. I almost flipped it end for end coming down one dune. I still occasionally see them used.
Lee
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Re: Fox 2.0 air shock setup
The Fox 2.0 air shocks use nitrogen gas and have internal damping. They should be good.
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Re: Fox 2.0 air shock setup
It is the term "air" vs. "gas" that I was talking to. Gas shocks are one thing, those other shock that are really "air shocks" you have to be very careful with. On the old "Buggytalk" site there was a guy using the air shocks or air bags (... I forget which as it as it was back around 2005 give or take when it happened) in a rail who was hurt quite badly because of their failure. I think he may have had a passenger who was hurt also.
Lee
- chuckput
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Re: Fox 2.0 air shock setup
Lee, Fox actually markets them as "air" shocks even though they use nitrogen. Here is what they say in their marketing material:
The design of the off-road Factory Race Series air shock allows for infinite adjustability of the spring rate by varying the nitrogen charge pressure. FOX's first air shock was invented by Bob Fox back in 1974 and has been highly refined in the 30-plus years we’ve been producing them.
The off-road Factory Race Series air shock uses the identical race-proven performance damping technology as our other Factory Race Series off-road shocks, so servicing and valving adjustments are the same. Incredibly strong yet lightweight hollow shock shafts further reduce weight on these shocks that are ideal for competition rock crawlers.
Body Smooth bore and honed seamless steel
Body Plating Zinc plated and clear coated for a long lasting finish
Components Black anodized, CNC machined 6061-T6 billet aluminum
Valving Tunable, velocity sensitive deburred valve shims
Seals Redundant sealing pack system, main seal, wiper seal, scraper seal
Oil JM92 Advanced Suspension Fluid for improved performance at variable temperatures
Shafts Hard chromed 4130 steel
Bearing Spherical, PFTE-lined, heat-treated alloy steel
Options Custom compression and rebound valving available (Add -1 to end of part number)
Adjustments Nitrogen Pressure
Extended 31.330
Compressed 19.330
Travel 12.000
Top Mount Eyelet
Bottom Mount Eyelet
Reservoir Emulsion
Mounting
Valving 40/90
MSRP $249.95
The design of the off-road Factory Race Series air shock allows for infinite adjustability of the spring rate by varying the nitrogen charge pressure. FOX's first air shock was invented by Bob Fox back in 1974 and has been highly refined in the 30-plus years we’ve been producing them.
The off-road Factory Race Series air shock uses the identical race-proven performance damping technology as our other Factory Race Series off-road shocks, so servicing and valving adjustments are the same. Incredibly strong yet lightweight hollow shock shafts further reduce weight on these shocks that are ideal for competition rock crawlers.
Body Smooth bore and honed seamless steel
Body Plating Zinc plated and clear coated for a long lasting finish
Components Black anodized, CNC machined 6061-T6 billet aluminum
Valving Tunable, velocity sensitive deburred valve shims
Seals Redundant sealing pack system, main seal, wiper seal, scraper seal
Oil JM92 Advanced Suspension Fluid for improved performance at variable temperatures
Shafts Hard chromed 4130 steel
Bearing Spherical, PFTE-lined, heat-treated alloy steel
Options Custom compression and rebound valving available (Add -1 to end of part number)
Adjustments Nitrogen Pressure
Extended 31.330
Compressed 19.330
Travel 12.000
Top Mount Eyelet
Bottom Mount Eyelet
Reservoir Emulsion
Mounting
Valving 40/90
MSRP $249.95
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Re: Fox 2.0 air shock setup
Chuck, I am aware of their use of the term but it is still a misnomer:
"Misnomer
A misnomer is a name that is incorrectly applied. Misnomers often arise because something was named long before its correct nature was known, or because an earlier form of something has been replaced by something to which the name no longer applies. A misnomer may also be simply a word that someone uses incorrectly or misleadingly. The word "misnomer" does not mean "misunderstanding" or "popular misconception", and a number of misnomers remain in common usage — which is to say that a word being a misnomer does not necessarily make usage of the word incorrect."
When I got my first pair of the rear air shocks (aka overload shocks that are the equivalent of "coil over shocks" used to support the rear springs on a truck), the type I was talking about back in the late 60's or early '70s, I seem to remember that even then the term was being misused on the fairly new/or starting to be used gas shocks (ignorance of the difference mostly I think because "air" is a gas also) even then but there was some trying to be stop the miss-used term as there was some confusion. As gas filled shocks became more common and the other shocks were be less so, due mostly to the dangerous problems that can be had using them assuming you were aware of the two or three different problems that could be caused (one of the reasons I brought the subject up).
Anyway, my point has been made and sorry it was on your posting string .
Lee
(If you want me to continue on the problems with using the air equivalent of coil overs I will as they can be good or good and dangerous.)
"Misnomer
A misnomer is a name that is incorrectly applied. Misnomers often arise because something was named long before its correct nature was known, or because an earlier form of something has been replaced by something to which the name no longer applies. A misnomer may also be simply a word that someone uses incorrectly or misleadingly. The word "misnomer" does not mean "misunderstanding" or "popular misconception", and a number of misnomers remain in common usage — which is to say that a word being a misnomer does not necessarily make usage of the word incorrect."
When I got my first pair of the rear air shocks (aka overload shocks that are the equivalent of "coil over shocks" used to support the rear springs on a truck), the type I was talking about back in the late 60's or early '70s, I seem to remember that even then the term was being misused on the fairly new/or starting to be used gas shocks (ignorance of the difference mostly I think because "air" is a gas also) even then but there was some trying to be stop the miss-used term as there was some confusion. As gas filled shocks became more common and the other shocks were be less so, due mostly to the dangerous problems that can be had using them assuming you were aware of the two or three different problems that could be caused (one of the reasons I brought the subject up).
Anyway, my point has been made and sorry it was on your posting string .
Lee
(If you want me to continue on the problems with using the air equivalent of coil overs I will as they can be good or good and dangerous.)
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Re: Fox 2.0 air shock setup
Ol'fog you can say whatever you want whenever you want. Good having you around. And thank you to chuckput, really nice people here at STF.
- Tom in PA
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Re: Fox 2.0 air shock setup
The problem with the old "air shocks" was they were more of a spring and not much of a shock. That lead to excessive rebound issues. The fox air shocks contain adjustable valving. They also have their limitations since the spring rate changes with temperature changes and some folks have had issues keeping good pressure over time. You also can't really "soften" your current torsion bars, you can only reduce preload. The spring rate does not change. If you index them too far to reduce preload your air shocks will actually have to push them back down to the stops. It can be and has been done, just not ideal.
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Re: Fox 2.0 air shock setup
Tom, remember the pix of the blue buggy with the soft top on in another post you saw today: I was coming down off a dune with the air shocks pumped up (they came on the buggy when I bought it and, since it came from a VW guy I thought that was the way to go so I kept them) when I hit the whoops at the bottom of the hill the rear end got bouncing more and more to the point where I was on the front wheels only and all I could see out the windshield was... sand! I had grabbed the steering wheel hard and luckily I didn't go over (endowed) but came down on the rear wheels then stopped. the buggy did stay on the front wheels for what seemed a loooooong time and I was scared as at the time it only had a show bar style of hoop, not a cage like it has now. The buggy came home and I then learned how to reset the preload then converted to the real thing type of gas shocks/dampeners. I did have to mess with the settings several times until I figured out that some of the advice I had been given was not the best.Tom in PA wrote: ↑Sun Jul 26, 2020 8:27 am The problem with the old "air shocks" was they were more of a spring and not much of a shock. That lead to excessive rebound issues. The fox air shocks contain adjustable valving. They also have their limitations since the spring rate changes with temperature changes and some folks have had issues keeping good pressure over time. You also can't really "soften" your current torsion bars, you can only reduce preload. The spring rate does not change. If you index them too far to reduce preload your air shocks will actually have to push them back down to the stops. It can be and has been done, just not ideal.
I then had a real cage built for it by a guy in Oregon who also built buggies.
Lee
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Re: Fox 2.0 air shock setup
Turns out, all the tech info. and mathematics are completely unnecessary. I want the shocks to sag about 30% of the stroke and so for that specific ride height the shocks will require a very specific amount of pressure. It's just that simple. I just set the ride height and now I can further tune the ride characteristics by adjusting the oil level, oil weight and valving. I'll find out if this actually works out and update here at the end of sept. Thanks all.
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Re: Fox 2.0 air shock setup
That sounds correct. Set the ride height then let the shocks/dampeners control the body and suspension (plus the tires) bouncing around (think of a squirt gun .)fredc125 wrote: ↑Sun Aug 02, 2020 1:27 am Turns out, all the tech info. and mathematics are completely unnecessary. I want the shocks to sag about 30% of the stroke and so for that specific ride height the shocks will require a very specific amount of pressure. It's just that simple. I just set the ride height and now I can further tune the ride characteristics by adjusting the oil level, oil weight and valving. I'll find out if this actually works out and update here at the end of sept. Thanks all.
Lee
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Re: Fox 2.0 air shock setup
i have 14 inch fox 2.0 air shocks on my jeep, i messed with them for a while when i first installed them. there is a really good write up on pirate 4x4. https://www.pirate4x4.com/threads/fox-air-shox.2702713/ probably the best write up on the internet about the how they work, and what does what. adding more oil affects the overall usable spring more oil less airspace would be like having a short stiff spring. less oil gives more room for air so its not as a dramatic of a spring curve. but your are right once you get ride height set then its a matter of messing with valving, and oil level. i like them on my jeep. not sure how i would like them in my baja bug... good luck with your set up
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Re: Fox 2.0 air shock setup
Just got back from the dunes and have an update. Turns out, getting the ride height correct is easy however,(at least in my case) that particular amount of air pressure wasn't nearly enough to keep the shock from bottoming out. I have two fox 2.0 air shocks( and two rancho 9000's for damping) on the rear of my vw sandrail and even with the fox shocks maxed at 500 psi each it would still bottom out fairly easily. So now I've got no sag and I'm smacking the motor on the ground over and over. I would have to say this setup was rather disappointing. I was able to crank up the torsion springs a bit to cure the bottoming but at that point I'm relying on the torsions so heavily I could probably have removed the air shocks altogether and been fine. I'm sure that between the shocks and the torsions I could probably tune it to work pretty good but that will have to wait till next season.
- Skidmark
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Re: Fox 2.0 air shock setup
I have Fox 2.0 emulsion shocks on my baja - the max pressure from Fox for mine is 220 psi. Double check with Fox for your particular shock and stay within the recommended pressure range. 500 psi sounds waaaaaaay high to me.
"Your car sounds angry, and it wants to go fast all the time..."
(quote from my daughter, after driving my car)
It's not complicated, it's just expensive...
(quote from my daughter, after driving my car)
It's not complicated, it's just expensive...
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Re: Fox 2.0 air shock setup
Not something I can use in my buggies but I do look and listen (then forget... I guess).
I hope this helps some.
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