Airshocks. Selection and tuning

[bdkw1]

Ok, I understand the method, but why is this the "right" way? You invented it? You read it somewhere?

OK, getting back to this. I wouldn't set-up a shock like that unless there were no other options and I had to run it that way temporarily till it could be changed to a better setup. That is the way I set up bumps though. For a shock, you would run the risk of going negative pressure on full droop due to it being to progressive. I would also never willingly setup a vehicle with 40% uptravel. I would also never willingly put emulsion shock on a vehicle. Adding more oil can cure problems up to a certain point where it starts to create some.

Oil volume tuning goes back to motorcycle forks. Before you could get different rate springs for the front of bikes you added more oil if you were a fat ass. This has just kind of carried over from that for Me.

As with all suspension tuning, it's a game of compromises.

 

[ArTi54N]

but it's usually still adjustable with a turn of the knob right?? or is that just with the expensive stuff??

 

[arse_sidewards]

I would also never willingly setup a vehicle with 40% uptravel

Why? 4 up 6 down would be perfectly normal and reasonable numbers for a heck of a lot of street and mild off road vehicles. 6" up and 9" down are numbers that wouldn't be out of place on a lot of buggies.

 

[Bebop]

OK, getting back to this. I wouldn't set-up a shock like that unless there were no other options and I had to run it that way temporarily till it could be changed to a better setup.

Provided that the vehicle owner wants/can change the setup...

That is the way I set up bumps though.

Interresting ! I've never touched them outside of changing pressure.

For a shock, you would run the risk of going negative pressure on full droop due to it being to progressive.

Negative pressure ? Even with your method, when filling shocks at full extension, you'd still end up with positive pressure, am I wrong ?

I would also never willingly setup a vehicle with 40% uptravel. I would also never willingly put emulsion shock on a vehicle. Adding more oil can cure problems up to a certain point where it starts to create some.

Some times you have to work with what you got.

Oil volume tuning goes back to motorcycle forks. Before you could get different rate springs for the front of bikes you added more oil if you were a fat ass. This has just kind of carried over from that for Me.

That mamkes 100% sense.

As with all suspension tuning, it's a game of compromises.

Absolutely.

 

[bdkw1]

Why? 4 up 6 down would be perfectly normal and reasonable numbers for a heck of a lot of street and mild off road vehicles. 6" up and 9" down are numbers that wouldn't be out of place on a lot of buggies.

6 up and 4 down sounds much better. Desert rigs are usually in the 60% uptravel range. This lets you get good spring rates without resorting to funny shit.

 

[bdkw1]

Negative pressure ? Even with your method, when filling shocks at full extension, you'd still end up with positive pressure, am I wrong ?

If your dealing with limited uptravel and trying to keep them from bottoming hard, the amount of oil you put in may make you have a vacuum when you fully extend the shock. Putting 50 PSI in at full droop would make your ride height to high so you set your pressure at ride height. This would be a really bad situation and your oil would break down quickly.

If you guys really wanted to go with the low uptravel route, you could use a shorter shock mounted as a slapper shock them have a long smooth body attached to the axle. This would net a good spring rate and not flop all over when it dropped out.

 

[Bebop]

6 up and 4 down sounds much better. Desert rigs are usually in the 60% uptravel range. This lets you get good spring rates without resorting to funny shit.

No offence, but I'm more worried about rockcrawlers than desert rigs.

If your dealing with limited uptravel and trying to keep them from bottoming hard, the amount of oil you put in may make you have a vacuum when you fully extend the shock. Putting 50 PSI in at full droop would make your ride height to high so you set your pressure at ride height. This would be a really bad situation and your oil would break down quickly.

That makes sense. But that's not the method you explained, that's why I was confused. I understand what you're saying and agree that vaccum would be terrible.

If you guys really wanted to go with the low uptravel route, you could use a shorter shock mounted as a slapper shock them have a long smooth body attached to the axle. This would net a good spring rate and not flop all over when it dropped out.

That looks like a desert solution not easy to implement to a rockcrawler.

 

[4R_on_the_Rocks]

If your dealing with limited uptravel and trying to keep them from bottoming hard, the amount of oil you put in may make you have a vacuum when you fully extend the shock. Putting 50 PSI in at full droop would make your ride height to high so you set your pressure at ride height. This would be a really bad situation and your oil would break down quickly.

If you guys really wanted to go with the low uptravel route, you could use a shorter shock mounted as a slapper shock them have a long smooth body attached to the axle. This would net a good spring rate and not flop all over when it dropped out.

Setting pressures at ride height goes against anything I’ve read, but this shouldn’t even be an argument if the shock manufacturers would provide basic manufacturer’s recommendations. This one thing ORI does well. I’m saying fox has a 5 page manual for all of their off-road shocks.

 

[Weasel]

It's actually the opposite of that which is why it sucks. Adding oil so that you only need double digit psi increases the spring rate curve to the moon. I guess if you're into pogo sticks it would be nice...lol

Well I had to go dig up my old sheets, couldn't even remember where I filed them. I retract what was said earlier. Your correct, I said it backwards.

Not exactly sure the line of thought I had but playing with 50psi and full of oil is far outside of what I had pictured in my mind.

 

[Weasel]

just for reference to maybe help avoid future basakwardness here a couple general rate charts. Using 500lbs unsprung per corner, 2.0" Walker 14" travel, ride height of 4" shaft showing.

50psi in the shocks at extension:

125psi at full extension:

200psi at full extension:

 

[AK_F250]

Like you would get anything else out of an emulsion shock with serious shaft displacement?

Airshocks as sold by shock company's are great for springs, shocks, not so much. If you think that they will do everything you need them to you are mistaken. They are plenty of ways to bandaid them but the basic design has many flaws. Unless you go resi out the bottom and start putting tubes on them you are going to have to live with the limitations.

I’ve got no dog in this fight and really dgaf about air shocks for anything I do , but I’m curious about how the bypass air shocks stack up. Ever messed with them?

 

[DesertCJ]

just for reference to maybe help avoid future basakwardness here a couple general rate charts. Using 500lbs unsprung per corner, 2.0" Walker 14" travel, ride height of 4" shaft showing.

50psi in the shocks at extension:


125psi at full extension:


200psi at full extension:

What am I looking at with the 50psi graph? Looks like it's showing the shock blow

 

[Weasel]

Pretty much, it doesn't work to make that ride height, with that weight and volume, it's past hydrolock.

 

[Bebop]

just for reference to maybe help avoid future basakwardness here a couple general rate charts. Using 500lbs unsprung per corner, 2.0" Walker 14" travel, ride height of 4" shaft showing.

50psi in the shocks at extension:


125psi at full extension:


200psi at full extension:

Weasel I'm glad you pulled the graphs. That makes way more sense to me and it matches what I was able to observe in real life.

 

[bdkw1]

I’ve got no dog in this fight and really dgaf about air shocks for anything I do , but I’m curious about how the bypass air shocks stack up. Ever messed with them?

Yes, they are what I have on My current build in progress. I have used them on other builds in the past and they work well. Downsides are lack of low speed damping. If you were running them by themselves, heavy poppet springs would help a little.

 

[bdkw1]

Pretty much, it doesn't work to make that ride height, with that weight and volume, it's past hydrolock.

Yes, with only 4" of shaft showing on a 14" shock you would be much better off with a C/O and using the secondary stops.

 

[Weasel]

Yes, with only 4" of shaft showing on a 14" shock you would be much better off with a C/O and using the secondary stops.

most crawlers run less, 2-3" showing.

 

[ParadisePWoffrd]

If your dealing with limited uptravel and trying to keep them from bottoming hard, the amount of oil you put in may make you have a vacuum when you fully extend the shock. Putting 50 PSI in at full droop would make your ride height to high so you set your pressure at ride height. This would be a really bad situation and your oil would break down quickly.

If you guys really wanted to go with the low uptravel route, you could use a shorter shock mounted as a slapper shock them have a long smooth body attached to the axle. This would net a good spring rate and not flop all over when it dropped out.

This is an interesting statement. I have thought about setting up a crawler with 6" air bumps, that were setup to hold the rig at ride height, and then using shocks, straps, and sway bars to control the suspension movement. It seems a little crazy, but should work in theory.

 

[Bebop]

This is an interesting statement. I have thought about setting up a crawler with 6" air bumps, that were setup to hold the rig at ride height, and then using shocks, straps, and sway bars to control the suspension movement. It seems a little crazy, but should work in theory.

What a miserable ride that would be.

 

[bdkw1]

What a miserable ride that would be.

Yes it would.

 

['84 Bronco II]

Bringing this back from the dead.

Does anyone make reservoir air shocks besides King? Theirs only appear to be available in 3 and 4 tube bypasses.

I see you can get single bypass (but still emulsion?) Radflos through Jesse Haines.

 

[bdkw1]

Bringing this back from the dead.

Does anyone make reservoir air shocks besides King? Theirs only appear to be available in 3 and 4 tube bypasses.

I see you can get single bypass (but still emulsion?) Radflos through Jesse Haines.

ADS will make whatever you want. Lead times are far better than Fox or King.

I had King make single tube resi airshocks, back then it a 6 week lead time. Now, it's more.

 

[bdkw1]

Won't speak for bdk1 but I would imagine that your spring rates end up to high which gives a non-complaint ride. Starting with a lower initial pressure moves the spring rate curve down as much as possible. But still tough when you setup everything with little up travel.

Circling back to this, your spring rate at ride hieght will be the same regardless of oil level. It takes X amount of force to hold the vehicle up at ride hieght. Preload or oil level dies not change this. It does change the rate above and below ride hieght. To have it effect your ride quality, you would need a pretty large jump in progressivness. Say like going from 300/300 on a coil over to a single 300 with a tender. With the double spring you have preload, with the single the tender keeps the spring from rattling on droop. Single springs have effectively negative preload. This is why I set up airshocks the way I do, aiming for less "preload" and more bump resistance.

 

[Dougal]

Do air struts run any sort of negative air-spring to taper them off to zero at the top?

 

[Crashhawk]

So, through all this, I've not seen any talk of oil weights.

What kind of info is out there?

 

[DesertCJ]

So, through all this, I've not seen any talk of oil weights.

What kind of info is out there?

I’ve seen someone use ATF. I started using ATF in my coil-overs because I always have it. Seems to work fine….

 

[arse_sidewards]

I’ve seen someone use ATF. I started using ATF in my coil-overs because I always have it. Seems to work fine….

I remember I read a few threads on Pirate back in the day where they figured out that there was some specific power steering fluid that was "perfect" or nearly perfect replacement for some high dollar brand name shock oil. ATF is pretty close. Wouldn't surprised me if it worked well enough.

 

[Dougal]

So, through all this, I've not seen any talk of oil weights.

What kind of info is out there?

That gets really interesting. For a start oil wt is an almost useless measurement. American and European oil companies seem to be using different scales.
Always go by centiStokes (cSt) intead. Water (at room temp) is 1 cSt. So 15 cSt oil is 15x thicker than water at the reference temp (usually 40°C/100°F).

Thinner oils naturally do better in both the hot and cold vs thicker oils. 15 cSt is the most common thin oil and often correlates to 2.5wt from European manufacturers and 5wt from American oil manufacturs.

ATF is 35cst. Matches some 7.5wt, some 8wt, some 10wt oils. wt scales are a mess.

 

[Crashhawk]

That gets really interesting. For a start oil wt is an almost useless measurement. American and European oil companies seem to be using different scales.
Always go by centiStokes (cSt) intead. Water (at room temp) is 1 cSt. So 15 cSt oil is 15x thicker than water at the reference temp (usually 40°C/100°F).

Thinner oils naturally do better in both the hot and cold vs thicker oils. 15 cSt is the most common thin oil and often correlates to 2.5wt from European manufacturers and 5wt from American oil manufacturs.

ATF is 35cst. Matches some 7.5wt, some 8wt, some 10wt oils. wt scales are a mess.

See this is beyond me. I'm looking for more of a "Hey here's my setup, here's what I run." type of thing.

 

[bdkw1]

Oils also get thinner at different rates. The less charge the more consistent the car will be. Thinner is better.

For most people, the best oil is one that is readily available to you. Always use the same oil.