Air Bags Over Coils

[Walking Eagle]

These are in the latest 4Wheel & Off-Road.

http://www.universalairsuspension.com/store/product_info.php?cPath=25&products_id=38

http://www.universalairsuspension.com/store/product_info.php?cPath=32&products_id=66

There was a thread earlier, someone askin about putting air bags over coils. It can be done with coil overs aparently. I don't know if at 0 psi they sit solid and only work off the coils, but it seems that way. Not nearly enough explaination.

 

[Taz]

I saw some like those on a TJ out at the Hammers a few weeks back. He was able to "dump" the air preasure on the front to keep it from unloading while climbing up the waterfalls. I don't know if it was the shocks, driving, or what but that jeep just wasn't as good as the toyotas!

 

[topend yobbo]

Lookk good but do they work ?

 

[SUMOTOY]

That's a lot of jake boys. It also is an application for a coil over shock. We with 80's don't have that, it might work on a gen 3 4runner. Also making a progressive rate spring requires 2 springs, the main and the helper. What's in the pictures is only a linear rate spring. I suspect someone will spend a LOT of money getting the rates close to where they need to be. Using only a linear rate coil over spring on any street driven machine really sucks, btdt.

What you want to look at is the airbag (from spring) conversion. This deletes the shock all together and substitutes air bags for springs. I suspect the setup for the Jeeps could be adapted easier than this coil over setup.

BTW, subaru had this exact setup starting in 1986, basically a bag over the upper spring perch.

Scott Justusson

 

[Walking Eagle]

That's a lot of jake boys. It also is an application for a coil over shock. We with 80's don't have that, it might work on a gen 3 4runner. Also making a progressive rate spring requires 2 springs, the main and the helper. What's in the pictures is only a linear rate spring. I suspect someone will spend a LOT of money getting the rates close to where they need to be. Using only a linear rate coil over spring on any street driven machine really sucks, btdt.

What you want to look at is the airbag (from spring) conversion. This deletes the shock all together and substitutes air bags for springs. I suspect the setup for the Jeeps could be adapted easier than this coil over setup.

BTW, subaru had this exact setup starting in 1986, basically a bag over the upper spring perch.

Scott Justusson

Going from coils to coil overs isn't that big a streatch. Oh, and most springs are not progressive springs. Oh, and an airbag does not delete the shock all together, it replaces the spring.

I don't think you really understand how this set-up works.

 

[SUMOTOY]

Going from coils to coil overs isn't that big a streatch. Oh, and most springs are not progressive springs. Oh, and an airbag does not delete the shock all together, it replaces the spring.

I don't think you really understand how this set-up works.

WE
I've done more coil over conversions in my shop than I care to count, I'm very familiar with them, how they work, fit and drive, street, track and off road.

This setup shown is a direct replacement for a coil over setup, as in a direct coil over shock replacement. Which means to make it fit an 80, you would need to do some massive fabrication, since a 'conversion' to a C/O setup requires it's placement at the 80 spring, not at the 80 shock. The two eyelets in the pic are indicators that this is for an existing C/O setup

Airbags definitely *can* replace shocks alltogether, some do, some don't. The ones that do, are able to have massive ride height changes with just air pressure. I saw a link to a jeep site with this setup, right on this very forum months ago.

Most coils ARE progressive springs in the auto/truck market. The reason is mostly for NVH, you put in linear rate springs, you have the disadvantage that it's a rough ride, from inch 0 of travel. This makes for a lot of road bucking (expansion joints esp) and very firm ride all the time, and damping changes tend to have little effect on that.

I use a lot of Ground Control coil overs in my shop. To make a progressive spring, you need the main spring and a helper spring. Both are linear rate springs, but both have different rates. The main spring is the longer of the 2 and then there is a intermediary spring perch, then a short (and lower rate) helper spring is above that, then the upper spring perch. This creates a progressive (technically dual rate) spring, and it takes a lot of tuning and swapping to get it right, btdt. And each application would be specific. The biggest issue with the 80 I see is the propensity to add a lot of aftermarket weight and equipment, which can really change the dictated spring rates.

An air bag insert can accomplish the same thing on a stock spring. Add in a couple spacers (or incorporate another airbag) , you can go from stock ride height up to the max travel of the shock.

This setup can be done, but not without issues, and it's already a whole bunch of money.

Scott Justusson

 

[Walking Eagle]

WE
This setup shown is a direct replacement for a coil over setup, as in a direct coil over shock replacement. Which means to make it fit an 80, you would need to do some massive fabrication, since a 'conversion' to a C/O setup requires it's placement at the 80 spring, not at the 80 shock. The two eyelets in the pic are indicators that this is for an existing C/O setup

Yes, I said it'd have to be coverted to C/O - that's not nearly as big a deal on an 80 as it would be on say a 60 or some other leaf spring rig.

Airbags definitely *can* replace shocks alltogether, some do, some don't. The ones that do, are able to have massive ride height changes with just air pressure. I saw a link to a jeep site with this setup, right on this very forum months ago.

Again - no, it can't. Exactly how do you propose that an airbag - which is just a different type of spring (like coils are different than leaves) - is going to control damping? Just like coils, or leaves, or coil overs, or struts, there still has to be some type of shock in the system.

This setup can be done, but not without issues, and it's already a whole bunch of money.

Scott Justusson

No one said it would be free. Someone in another thread was talking about putting airbags over coils, then completely deflating the air bags to ride on the coils - which won't work for a number of reasons that were discussed in that thread. This is another option to accomplish what that person was after. No need to trash the idea - or have you seen this in use on a 80 and seen it not work?

 

[SUMOTOY]

Yes, I said it'd have to be coverted to C/O - that's not nearly as big a deal on an 80 as it would be on say a 60 or some other leaf spring rig.

That's a lot of jake WE. It 'starts' at 2600. You need to do upper and lower perches, and possibly relocate the shocks (if not deleting them)

Again - no, it can't. Exactly how do you propose that an airbag - which is just a different type of spring (like coils are different than leaves) - is going to control damping? Just like coils, or leaves, or coil overs, or struts, there still has to be some type of shock in the system.

Look at the back of any tractor trailer, it is damped and sprung by airbags. I'll try to find the jeep/ford application. I actually watched one of the cable shows convert a ford truck to it, ony airbags, nothing else. Required a whole susp frame and a huge air tank as well.

No one said it would be free. Someone in another thread was talking about putting airbags over coils, then completely deflating the air bags to ride on the coils - which won't work for a number of reasons that were discussed in that thread. This is another option to accomplish what that person was after. No need to trash the idea - or have you seen this in use on a 80 and seen it not work?

This is the tech forum WE. The application has technical issues that I can put forth from my experience with 15 years of coil over setups. I propose that the application pictured won't work on an 80 without major fabrication, starting with a different application all together than the one pictured. Then, you'd have to figure out what your spring rates are going to be, which from my btdt, is a lot of engineering, then a lot of actual testing (standard linear spring rates are in 25inch/lb rate increments and 1in length increments). Then, add in a dual rate spring, you'd have more variables to consider. Free? I suspect by the time you are done, you could just buy another 80 that's already lifted.

Why not just leave the spring and add a shock that has a lift bag? I know from installing a few sets of springs, shocks and airbags, the only thing limiting the stock spring on the truck is the extended length of the shock. That's a farily easy solution comparatively speaking. You could approach it from a given applicaiton air bag over shock, or use the stock shock and add air bag lift above or below it.

WE, tossing out options is what a technical forum is all about. I see a lot of issues in variable raising a truck, from mounting to control. Given the suspension geometry changes during lift that's already on the forums and Slee's site (and at range rover), I'd also suspect the first thing would be to define the 'range' required of the setup to acceptable geometry/tire fitment vs control issues. Then go after which technology would accomplish that gaol the best. Without using any software or computer input, I suspect the range would be in the stock>2in lift range. If that's the case, the price shouldn't be anywhere close to 'starting at' 2600.

Figure the goals, then engineer the solutions. Part of that goal setting, is what's realistic in terms of target v goals and price. Over half my job in automotive tweeks, is putting that reality on paper. It's tough love, or just the rational side of great ideas. Better to get it done based on that, then finish it and find out the engineering solution worked, just didn't address the goal. I'd rather upset em a bit at the beginning, btdt2.


Scott Justusson

 

[Walking Eagle]

Look at the back of any tractor trailer, it is damped and sprung by airbags. I'll try to find the jeep/ford application. I actually watched one of the cable shows convert a ford truck to it, ony airbags, nothing else. Required a whole susp frame and a huge air tank as well.
Scott Justusson

Probably was something like this that has the shock inside the airbag.



That's what you normally see for vehicles that had struts to begin with. More common is this.

 

[Taz]

shocks

all the air sprung semis I've seen have shocks as well.

 

[SUMOTOY]

Probably was something like this that has the shock inside the airbag.

That's what you normally see for vehicles that had struts to begin with. More common is this.

No, this one used the bag as the the coil and the damper both. The advantage being that it had some massive travel capabillity. The reason for the shock relocation in the kits you mention is that you need to change the suspension geometry and mounting points so that large changes in height don't contribute to large changes is caster, cambar and toe. Hardly an easy project in the 80. Even with a 4in lift, caster on an 80 is compromised enough to affect driveability.

I'll try to get a search in on the airbag systems I speak of sometime today.

SJ

 

[clownmidget]

Noobs

This is pretty reminiscent of this 2003 thread. A. Podvin had an 80-series on airbags that eventually went on eBay IIRC. P. Straub also has them on Tippy w/ no shocks - but that's not really streetable :hillbilly

 

[Walking Eagle]

Noobs
P. Straub also has them on Tippy w/ no shocks - but that's not really streetable :hillbilly

People run coil spring and leaf springs without shocks too - not real streetable like you say.

There have been several threads on Mud too about air bags - the air bag with coil overs is new - at least as far as I know

This is one of my favorites

http://www.overthehill4x4.com/Airbag.html

 

[Walking Eagle]

That's a lot of jake WE. It 'starts' at 2600. You need to do upper and lower perches, and possibly relocate the shocks (if not deleting them)


Scott Justusson

Why on earth would you relocate the shocks if you're going to a coil over system? The shock is in the coil over.

 

[LT]

People run coil spring and leaf springs without shocks too - not real streetable like you say.

There have been several threads on Mud too about air bags - the air bag with coil overs is new - at least as far as I know

This is one of my favorites

http://www.overthehill4x4.com/Airbag.html

W and Desmond in our club Cascade Cruisers run air bags and both love 'em. They are able to do some stuff that no one else can simply because they can control the lean of their vehicle. Since W is still carbed and he wants to climb a vertical wall he will air down the front completely and air up the rear all the way and go at it.

The one downside is that you are always screwing around with the bags to get the right height. W likes to mess around with his bags alot while Desmond just leaves them generally in one spot.

 

[SUMOTOY]

Why on earth would you relocate the shocks if you're going to a coil over system? The shock is in the coil over.

My question would be the reverse, why use an expensive coil over system, when all you need is airbags to replace the spring? 90+% of the time, coil overs replace either coil overs, or leaf springs. But, to answer your question directly WE, the reason (on the 80 anyhow) for shock relocation using an airbag setup, the airbag to shock clearance/interference would be really tight on the front.

You can go airbag and leave the shock (albeit relocated in the front) if you want, it's more common, and cheaper. Again, I'd ask what's the target. As you can see from the above, if it's *only* ground clearance and articulation, delete the shock. I can't comment on streetable or not, haven't driven one without the shock. I do know they exist, and are offered commercially. With some of the newer bag technology and reduced cost, I suspect we'll see more airbag stuff from the factory marques.

After raising my 4runner 2inches, I set my goal to achieve some ride height adjustability with the 80, but was concerned about the top heavy nature of doing so (and yes, fitting it into my garage at home). So *my* design was simple and cheap. Use the spec application airbag for the rear from Air Lift, and modify the front upper spring perch to take a spec application from Air Lift. *IF* I wanted to go higher, I would contact a shock manufacturer to find a longer extended dimension shock for the 80, and possibly spec a longer airbag for the front and/or rear. There is a lot of travel on that stock spring.

I can't post up a before and after measures of hub to wheel lip, but can certainly compare 'after' data, since all the rest of my truck is factory stock (wheels, tire size, springs, shocks)

My total investment into 'lift' = under 200USD. Stock springs, stock shocks. From this experience and btdt on the 80, it certainly seems to me that 'lifting' an 80 can be accomplished with airbag inserts and possibly a different shock for a fraction of the cost of a coil over conversion.

YMMV?

Scott Justusson
94 FZJ80 SC + Airbag insert 'lift'

 

[SUMOTOY]

W and Desmond in our club Cascade Cruisers run air bags and both love 'em. They are able to do some stuff that no one else can simply because they can control the lean of their vehicle. Since W is still carbed and he wants to climb a vertical wall he will air down the front completely and air up the rear all the way and go at it.

The one downside is that you are always screwing around with the bags to get the right height. W likes to mess around with his bags alot while Desmond just leaves them generally in one spot.

Enter electronics. Air Lift and others sell an incab electronic airbag controller, that has min, standard, and lifted height settings, 2 of the airlift ones could control 4 airbag setups. It automatically sets the bags to those settings, or you can override them with the +/- touchpad. I plan on installing one of these units on my insert setup this summer.

I also found in my experience with 'adjustable' coil overs, few do. Once a setting is found and tuned as 'optimal', few tinker with it. I could see more with offroading, but I suspect a standard and lifted mode is probably more than adequate for most.

SJ

 

[e9999]

it seems that the very nature of an airbag precludes it from working as a shock absorber, i.e. a dampening device. What would be causing significant energy absorption and dynamic delay in an airbag assuming that they are not playing with air going in and out through minuscule orifices etc?

 

[Walking Eagle]

My question would be the reverse, why use an expensive coil over system, when all you need is airbags to replace the spring? 90+% of the time, coil overs replace either coil overs, or leaf springs. But, to answer your question directly WE, the reason (on the 80 anyhow) for shock relocation using an airbag setup, the airbag to shock clearance/interference would be really tight on the front.

Your other post said that with a coil over conversion you would need to relocate the shock. There is no need. Once you've mounted the coil over, you've also mounted the shock. Now you're changing to talking about airbags which is different than coil overs or coil overs with bags.

You can go airbag and leave the shock (albeit relocated in the front) if you want, it's more common, and cheaper. Again, I'd ask what's the target. As you can see from the above, if it's *only* ground clearance and articulation, delete the shock. I can't comment on streetable or not, haven't driven one without the shock. I do know they exist, and are offered commercially. With some of the newer bag technology and reduced cost, I suspect we'll see more airbag stuff from the factory marques.

Without shocks it'll bounce down the road unrestrained, if it's got bags, coils or leaves.

Please prove that there are airbags that work as shocks. Not air bags that do not have the shocks integrated and run seperate shocks, but air bags that provide the damping characteristics of a shock on their own. You've said they exist - show us.

After raising my 4runner 2inches, I set my goal to achieve some ride height adjustability with the 80, but was concerned about the top heavy nature of doing so (and yes, fitting it into my garage at home). So *my* design was simple and cheap. Use the spec application airbag for the rear from Air Lift, and modify the front upper spring perch to take a spec application from Air Lift. *IF* I wanted to go higher, I would contact a shock manufacturer to find a longer extended dimension shock for the 80, and possibly spec a longer airbag for the front and/or rear. There is a lot of travel on that stock spring.

I can't post up a before and after measures of hub to wheel lip, but can certainly compare 'after' data, since all the rest of my truck is factory stock (wheels, tire size, springs, shocks)

My total investment into 'lift' = under 200USD. Stock springs, stock shocks. From this experience and btdt on the 80, it certainly seems to me that 'lifting' an 80 can be accomplished with airbag inserts and possibly a different shock for a fraction of the cost of a coil over conversion.

YMMV?

Scott Justusson
94 FZJ80 SC + Airbag insert 'lift'

This is not doing at all what was discussed at the beginning of this thread

https://forum.ih8mud.com/showthread.php?t=76299

Sure - you can put airlift coil inserts in and raise the effective spring rate, which will give you a little more lift. It'll also ride stiffer. Cheap. Sure. So are coil spacers. The ultimate solution for everyone? Hell no. Is this probably the closest to what some want - Ride like you're on normal springs 90% of the time, and have adjustability for the 10% - probably the closest I've seen. Since they advertise running at 0psi, it seems like it might be exactly that. The caviot is does the bag allow something to bottom out and run only on the spring. No one has answered that question yet.

 

[LT]

it seems that the very nature of an airbag precludes it from working as a shock absorber, i.e. a dampening device. What would be causing significant energy absorption and dynamic delay in an airbag assuming that they are not playing with air going in and out through minuscule orifices etc?

Uh... you run shocks with air bags.