Air Bags Over Coils

[LT]

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

Yeah, W and James of Over The Hill were talking about it for a customers rig. They are doing a FJ45 project on a FJ55 frame. It is set up with air bags but the customer doesn't want it to be noisey so hand tweaking it out of the question. I think for off road application I would rather have individual control of the air bags. If it was dual purpose rig I would go with electronics, just isn't worth the time sitting on the road always screwing around with how much air in the bags to get it to drive right.

 

[SUMOTOY]

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.

I reiterate the question: What is the target. It would seem to me that we are speaking to raising and lowering ride height. Why raise and lower ride height? I'm not sure I understand the caviot WE, what are you trying to achieve there? Articulation? An airbag or insert can deform. Want more articulation, run a narrower diameter airbag insert (I asked this tech question of the folks at Air Lift). Let's not forget that given the target, there won't be an 'ultimate' solution WE. The problem I see with the coil overs above is you are exactly *not* running on normal springs 90% of the time. A normal spring for an 80 is progressive, front and rear. The 'best" you can get from the above setup is a dual rate spring, the given in the above pictured setup is a linear rate spring. Run on the street with a linear rate spring, "normal" is the last description you will use to describe the ride, btdt. Run a dual rate progressive? Fine, add another 400+ worth of hardware to the price right off the bat.

There can't be an ultimate solution, because you set the suspension geometry for a given height, you have a narrow range of adjustment before caster interferes with driveability, and you have shocks that have a narrow range of optimal valving function. And, we know from just looking around, that a dedicated purpose vehicle will always outperform a dual purpose. So, 'ultimate' will have all sorts of compromises. 'Starting at 2600' for these compromises sounds intimidating. Why I asked the target and goals. For that kind of money vs *performance gains* (still not defined: Let's assume it to be additional offroad performance with lift), you'd be better off with a proven solution of buying a set of lockers, and another set of wheels with dedicated off road tires.


For example
Factory Lockers = 1300
airbag inserts = 200 (+/-2in)
stock wheels and tires = 0 (baseline)
34in offroad wheels on stock rims = 1000 (+1.5in)
====================================
Total to go up 3.5in = 2500

If the goal is to 'occasionally' go up 3.5inches and have more offroad capabillity, the locker boys can do it for 1200.

The coil over option certainly is *an* option WE. Without clearly defining the goals regarding 'lift', I'd be hesitant to consider it a viable one. The price alone (without anybody actually absorbing the cost of testing it = more dollars) puts a lot of other proven performance options up for discussion.

Also happy to admit that my design isn't for everyone. My goal was adjustability (0- 2in) with additional capacity. Easily met with minor modifications to the front spring perch, and a bit of tech research. Did it, and it's done, and it meets and exceeds my expectations (albiet rather low I'll admit). I suspect a coil over conversion could also meet that objective too. The question is, will it exceed the goals or performance of airbag inserts? I have my doubts based on my coil over experience, but I'd be happy to be proven wrong with the comparo option already on my truck. Glad I snagged the cheap option first....



SJ

 

[Walking Eagle]

I reiterate the question: What is the target. It would seem to me that we are speaking to raising and lowering ride height. Why raise and lower ride height? I'm not sure I understand the caviot WE, what are you trying to achieve there? Articulation? An airbag or insert can deform. Want more articulation, run a narrower diameter airbag insert (I asked this tech question of the folks at Air Lift). Let's not forget that given the target, there won't be an 'ultimate' solution WE.

Ask the person on the other thread their target. My target would be to have the ability to raise the suspension only for off road and not suffer the drawbacks on road. The ability to max out extension on the front to not hit the bumper when trying a tall step. Level out off-cambers, ect. All the same advantages of running a pure airbag set-up. Your airbag inserts don't count as a real airbag set-up - sorry.

The problem I see with the coil overs above is you are exactly *not* running on normal springs 90% of the time. A normal spring for an 80 is progressive, front and rear. The 'best" you can get from the above setup is a dual rate spring, the given in the above pictured setup is a linear rate spring. Run on the street with a linear rate spring, "normal" is the last description you will use to describe the ride, btdt. Run a dual rate progressive? Fine, add another 400+ worth of hardware to the price right off the bat. .

From the OME web site

"Diversity

Constant and variable rate coils are available to suit a wide variety of applications – even those you thought were impossible."

Here's the sway away kit for tacoma's - non-progressive spring

http://www.performanceproducts4truc...577&name=Sway-A-Way+Race+Runner+Coilover+Kits

more single rate

http://www.performanceproducts4truc...rmance+Products+Front+Coil-Over+Leveling+Kits

even more single rate torsion bars and coils

http://www.downeyoff-road.com/SuspensionComponents/index.htm

And since you can put any type of spring in a coil over you like, you certainly could put a progressive spring in there.

There can't be an ultimate solution, because you set the suspension geometry for a given height, you have a narrow range of adjustment before caster interferes with driveability, and you have shocks that have a narrow range of optimal valving function.

Sure there can be an ultimate solution. Who cares about the caster change with air bags over coils? First off if it was such a big deal a switch to 3 or 4 link would fix it. But, since we're talking about only using the bags for temporary clearance, forced articulation and camber adjustements off road at <10 and probably <5 mph, the change in caster will probably never be noticed. That's much more of an issue at hwy speeds. I certainly wouldn't suggest setting the caster at the aired down height, and then airing them up all the way to run on the street.

And, we know from just looking around, that a dedicated purpose vehicle will always outperform a dual purpose.

Duh.

So, 'ultimate' will have all sorts of compromises. 'Starting at 2600' for these compromises sounds intimidating. Why I asked the target and goals. For that kind of money vs *performance gains* (still not defined: Let's assume it to be additional offroad performance with lift), you'd be better off with a proven solution of buying a set of lockers, and another set of wheels with dedicated off road tires.


For example
Factory Lockers = 1300
airbag inserts = 200 (+/-2in)
stock wheels and tires = 0 (baseline)
34in offroad wheels on stock rims = 1000 (+1.5in)
====================================
Total to go up 3.5in = 2500

If the goal is to 'occasionally' go up 3.5inches and have more offroad capabillity, the locker boys can do it for 1200.

Already have lockers. Already have a second set of rims for off-road tires. A more traditional set-up doesn't get you the advantage offered by bags, or bags over springs. Actually, I already have a set of J's sitting in the garage I got so cheap as to prevent looking at any bag option in the near future, as coil replacements or in combo with coil overs.

The coil over option certainly is *an* option WE. Without clearly defining the goals regarding 'lift', I'd be hesitant to consider it a viable one. The price alone (without anybody actually absorbing the cost of testing it = more dollars) puts a lot of other proven performance options up for discussion.

There aren't any proven performance options that give this adjustability. The biggest advantage - if the bags truly can run at 0psi and bottom out, is you can run a fairly stiff spring to give good road maners. Then as you start to fill the bag, it raises the truck, and it also gives a soft spring rate up to the point that it's supper firm. That's really the ideal (or ultimate) for a dual purpose rig. To be able to ride low and firm on the road, and high and soft off road. That's the biggest draw back to airbags replacing the coils - the higher you go for clearance, the stiffer the suspension is, and the less compliant it is. Your inserts have the same exact drawback.

I suspect a coil over conversion could also meet that objective too. The question is, will it exceed the goals or performance of airbag inserts? I have my doubts based on my coil over experience, but I'd be happy to be proven wrong with the comparo option already on my truck.

I have no doubt that it would exceed the performance of airbag inserts both on and off-road. But greater performance generally costs more. Like the old addage from Mad Max "Speed is a matter of money, how fast do you want to go."

BTW - you still haven't shown the airbags that provide damping like a shock, but do not incorporate a shock.

 

[SUMOTOY]

Ask the person on the other thread their target. My target would be to have the ability to raise the suspension only for off road and not suffer the drawbacks on road. The ability to max out extension on the front to not hit the bumper when trying a tall step. Level out off-cambers, ect. All the same advantages of running a pure airbag set-up. Your airbag inserts don't count as a real airbag set-up - sorry.

I believe if you look below, that's not true, but hey I'm willing to be the cheap *ss motorsport poser.

From the OME web site

"Diversity

Constant and variable rate coils are available to suit a wide variety of applications – even those you thought were impossible."

Here's the sway away kit for tacoma's - non-progressive spring

more single rate

even more single rate torsion bars and coils

And since you can put any type of spring in a coil over you like, you certainly could put a progressive spring in there.

Not a true statement. You can't put any type of spring in a coil over you like (and all the examples above are linear rates btw). Remember, coil overs use flat tops and bottom going to a non oriented flat spring perch. Stock coils on the 80 use an oriented spring perch. You can 'build' a dual rate spring with the eibach setup. Progressive springs are special order, and very limited in rate, btdt. Without a commitment to the 80 chassis, you really are limited to an off the shelf coil over setup, or one from a different application alltogether. Then there are some issues with length vs bind, collapse and max compression. In a offroad situation, I'd be after progressive springs, becuase it gives you the most articulation. IF that's in the target.

Sure there can be an ultimate solution. Who cares about the caster change with air bags over coils? First off if it was such a big deal a switch to 3 or 4 link would fix it. But, since we're talking about only using the bags for temporary clearance, forced articulation and camber adjustements off road at <10 and probably <5 mph, the change in caster will probably never be noticed.

Toe might be noticed, camber vs traction might be noticed. Again, I believe you are limited in the 'ultimate' if you design this system in detail. I suspect, when all the money is spent on this system, the compromises vs performance (or bang for buck) won't be considered ultimate. Again, happy to have someone prove otherwise.

Already have lockers. Already have a second set of rims for off-road tires. A more traditional set-up doesn't get you the advantage offered by bags, or bags over springs. Actually, I already have a set of J's sitting in the garage I got so cheap as to prevent looking at any bag option in the near future, as coil replacements or in combo with coil overs.

If we are looking at addressing 10% of the driving, make a dual purpose that requires very little effort to gain a lot of tractive performance. A bit of air, and a larger diameter tire, can gain you a lot of lift with minimal effort. For an additional 3k+, you could go with the air coil overs. I'd sure look at the Land Rover sites to find it's compromises. I'd sure want to get some testing done on defining the ultimate vs articulation (like the issues, constraints and proposed testing found here: http://www.yellowdefender.com/twist_off_1999/rules/ )

There aren't any proven performance options that give this adjustability. The biggest advantage - if the bags truly can run at 0psi and bottom out, is you can run a fairly stiff spring to give good road maners. Then as you start to fill the bag, it raises the truck, and it also gives a soft spring rate up to the point that it's supper firm. That's really the ideal (or ultimate) for a dual purpose rig. To be able to ride low and firm on the road, and high and soft off road. That's the biggest draw back to airbags replacing the coils - the higher you go for clearance, the stiffer the suspension is, and the less compliant it is. Your inserts have the same exact drawback.

I believe on a dual purpose rig, you will have offsetting compromises. Specifically, an airbag with a progressive spring vs coil overs with a linear or dual rate spring. I also believe if you think about it a second, lift by air is lift by air. Both systems allow drop of one axle to the extended length of the shock. Both systems under "lift" condition will restrict the compressed length of apposing axle. So, you can only make the statement above if you use a linear or dual rate spring that's softer than a stock progressive spring. At which point you are back to comparing a linear to a progressive spring with air bag.

WE, if you look at most c/o setups, the extended length of the shock is based on mostly universal applications. Which means, to get the adjustable ride height, you usually end up with a longer shock extended length than the unloaded spring. Which means you normall tether a coil over with cable to make the unloaded height = unloaded spring length. This is required so that the spring doesn't leave the perch and get jammed when it goes back to the compressed length. I've used these tethers on jumping prorally cars. Another extended dimension advantage to the stock progressive spring.

I have no doubt that it would exceed the performance of airbag inserts both on and off-road. But greater performance generally costs more. Like the old addage from Mad Max "Speed is a matter of money, how fast do you want to go."

I'm glad you are convinced WE. I'm not convinced of it at all, but I also question "greater" performance with a minimal increase in ground clearance, all other tractive factors maximized. I suspect that more than 'just' offroad tires could offset that difference, like get 'rock' 'mudders' 'snow' 'sand' tire and wheel packages. Assuming the target is maximizing offroad traction.

BTW - you still haven't shown the airbags that provide damping like a shock, but do not incorporate a shock.

I'll suffice it to say it's been done. Is it the 'ultimate'? On road I doubt it, but I'd sure think one could easily reach below the truck and hit the swaybar disconnects AND the shock disconnects with a non coil over airbag system. Dual purpose, and much greater performance than any coil over air system, no 4 link mods necessary. Cheaper too. What's the target?

The system I have is far from the ultimate, but I explored *all* options before settling on it. Short of building a single purpose machine, it appears to me to have the best bang for buck value given my targets of some ride height adjustabilty and extra capacity. I hope anyone considering the coil over airbag option gets some massive well defined performance gains, cuz they spent all the money to get there.

SJ

 

[Walking Eagle]

IToe might be noticed, camber vs traction might be noticed.

That's an interesting theory - the toe on a solid axle truck is going to be changed by the suspension moving up and down. Not exactly sure how you're going to get the tie rod to get longer and shorter - but that's certainly a theory.

I also believe if you think about it a second, lift by air is lift by air. Both systems allow drop of one axle to the extended length of the shock. Both systems under "lift" condition will restrict the compressed length of apposing axle. So, you can only make the statement above if you use a linear or dual rate spring that's softer than a stock progressive spring. At which point you are back to comparing a linear to a progressive spring with air bag.

You're missing the point completely - the idea is to be able to run without any air in the bags - you can't do that with your air-lifts, and you can't do it with straight bags.

I'm glad you are convinced WE. I'm not convinced of it at all, but I also question "greater" performance with a minimal increase in ground clearance, all other tractive factors maximized. I suspect that more than 'just' offroad tires could offset that difference, like get 'rock' 'mudders' 'snow' 'sand' tire and wheel packages. Assuming the target is maximizing offroad traction.

Ok, you're not convinced, but you also state that toe is effected by lift and going to effect traction, so I'm not surprised. Were did you get this minimal increase in ground clearance idea? In what book is 5+" a minimal increase? You're insert lift is probably minimal, this is not. Try reading about it a little before commenting. Who's talking about tractive factors? We're talking about gaining clearance from using a system like this, and gaining forced articulation, and the ability to level on off camber hills ect. Assuming the target is maximizing offroad traction - once you're hung up on your bumpers, or your frame, you pretty much don't have any traction, just tires spinning in the air.

BTW - you still haven't shown the airbags that provide damping like a shock, but do not incorporate a shock.

I'll suffice it to say it's been done.

sorry, that does not suffice. You've claimed it two or three times, and everyone else who's posted says it's not right. You claim to know it - prove it - or retract it.

Is it the 'ultimate'? On road I doubt it, but I'd sure think one could easily reach below the truck and hit the swaybar disconnects AND the shock disconnects with a non coil over airbag system. Dual purpose, and much greater performance than any coil over air system, no 4 link mods necessary. Cheaper too. What's the target?

Uhm... no 4 link necessary with coil overs either - I only mentioned it as an option to maintain more constant caster with extreme travel - same tech. that's been done on 80's here on Mud for coil springs.

Why do you keep asking what's the target? I told you what it was. You don't seem to get it. So I'm going back to my origonal post.

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

http://www.universalairsuspension.co...products_id=38

http://www.universalairsuspension.co...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."

Or to paraphrase - "Hey ya'all, saw these in a mag, thought someone other than sumotoy might be interested"

 

[firetruck41]

I keep getting this message:

This message is hidden because SUMOTOY is on your ignore list.

 

[SUMOTOY]

That's an interesting theory - the toe on a solid axle truck is going to be changed by the suspension moving up and down. Not exactly sure how you're going to get the tie rod to get longer and shorter - but that's certainly a theory.

Got that one, WE. Not thinking in the solid axle sense. My bad, you still enjoy the same bumpsteer problems with a lot of uncorrected lift however.

You're missing the point completely - the idea is to be able to run without any air in the bags - you can't do that with your air-lifts, and you can't do it with straight bags.

I miss the target, not the point. You run a linear rate spring vs a progressive rate spring. Assign a rate to the stock progressives on the truck, then pick a spring rate for the linear spring. The issue is tradeoff's and compromises vs articulation and testing vs goals and targets.

Ok, you're not convinced, but you also state that toe is effected by lift and going to effect traction, so I'm not surprised. Were did you get this minimal increase in ground clearance idea? In what book is 5+" a minimal increase? You're insert lift is probably minimal, this is not. Try reading about it a little before commenting. Who's talking about tractive factors? We're talking about gaining clearance from using a system like this, and gaining forced articulation, and the ability to level on off camber hills ect. Assuming the target is maximizing offroad traction - once you're hung up on your bumpers, or your frame, you pretty much don't have any traction, just tires spinning in the air.

A true statement about hang up, ck out the defender site, my question would be at what height would those 'benefits' be offset by the cg of the truck. To go with 6in of 'adjustable' lift, you need to address all the Ackermann Effect issues that come into play: sway bar drop (or disconnect), rear brake bias rod, driveshaft articulation limitations, panhard rod issues (as you lift, rod gets shorter, the axle goes sideways), rear pinion angle changes from rear upper control arms. These are why I don't buy into the advertisement of "6inches of lift" when applied specifically to the 80. I suspect in reality on an 80 it's less than 3inches, cuz at 4inches of 80 lift specifically, Slee wants to sell you a bunch of hardware addressing the above.

sorry, that does not suffice. You've claimed it two or three times, and everyone else who's posted says it's not right. You claim to know it - prove it - or retract it.

WE, you can run airbags with the shocks or without them offroad, just like the swaybars. Disconnecting them gives maximum articulation. A known compromise to disconnecting them is streetability. Target includes quick disconnects for the swaybars, drop blocks for the swaybars, or no swaybars at all?

Uhm... no 4 link necessary with coil overs either - I only mentioned it as an option to maintain more constant caster with extreme travel - same tech. that's been done on 80's here on Mud for coil springs.

Affects on road drivability. Part of the target?

Why do you keep asking what's the target? I told you what it was. You don't seem to get it. So I'm going back to my origonal post.

I ask because one needs to keep in mind that on an 80, adjustabilty will have it's limitations given your undefined target. Maybe Christo can address the specific issue Slee runs into when raising trucks. For starters go here: http://www.sleeoffroad.com/technical/tz_35.htm From the product website, even with 4in of lift I see all Ackermann Effect issues mentioned above. So on top of that 2600, you have a lot of limiting issues, from driveline hardware articulation to braking, to linear spring rates. The airbag c/o's are neat products in general, quite daunting when applied to an 80. So much so, I would suspect the first one going this route will exceed the value of a second truck already dedicated lifted. Possible? Anything's possible like you said.

Or to paraphrase - "Hey ya'all, saw these in a mag, thought someone other than sumotoy might be interested"

hehe. Good chatter without the beers to add arm waving and pen on napkins at the bar WE, but technical issues really prevent this from being a reality for now. I would love to see someone do it, to find the actual limitations and test vs chatting it up. I look at mags all the time for new products in my shop. Putting it up for discussion if it appears viable. Someone other than me OR you would have to commit in a big way to go from interest to implementation.

Put the mag down and leave it in the john WE, time for another beer (Ok I'll buy the first one for stubbing my toe on toe comment). Steering wheel turned massively to the left, I remain...

Slightly uplifted.



SJ

 

[Walking Eagle]

I keep getting this message:

This message is hidden because SUMOTOY is on your ignore list.

I think I need to do that....

 

[Walking Eagle]

Sumotoy -

First you said:

"Airbags definitely *can* replace shocks alltogether, some do, some don't."

Followed by:

"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."

and:

"No, this one used the bag as the the coil and the damper both. The advantage being that it had some massive travel capabillity."

And finally:

"I'll suffice it to say it's been done. "

Once you fess up that you're wrong on that too, then I'll explain the errors in the logic you have below.

:
A true statement about hang up, ck out the defender site, my question would be at what height would those 'benefits' be offset by the cg of the truck. To go with 6in of 'adjustable' lift, you need to address all the Ackermann Effect issues that come into play: sway bar drop (or disconnect), rear brake bias rod, driveshaft articulation limitations, panhard rod issues (as you lift, rod gets shorter, the axle goes sideways), rear pinion angle changes from rear upper control arms. These are why I don't buy into the advertisement of "6inches of lift" when applied specifically to the 80. I suspect in reality on an 80 it's less than 3inches, cuz at 4inches of 80 lift specifically, Slee wants to sell you a bunch of hardware addressing the above.

 

[SUMOTOY]

Sumotoy -

First you said:

"Airbags definitely *can* replace shocks alltogether, some do, some don't."

Followed by:

"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."

and:

"No, this one used the bag as the the coil and the damper both. The advantage being that it had some massive travel capabillity."

And finally:

"I'll suffice it to say it's been done. "

Once you fess up that you're wrong on that too, then I'll explain the errors in the logic you have below.

The reason I wanted to leave it at a "I'll suffice it to say it's been done" is that this is the 80 tech forum. WE, to go further down that path, we have to look at the roots of 'adjustable' suspensions for the last 30 years, the lowrider boys. And let us not forget that they have adapted to the new airbag technology. I enjoy going to the LR parades here in Chicago, cuz they have the largest turnouts in the country. I've also enjoyed seeing some of the best applications of lift and drop, from all out chrome to cheap *ss motorsport solutions. Very few use the shocks to acheive maximum articulation with airbags. Daily street drivers too. Find the shock here:

http://lowridermagazine.com/tech/0603_lrm_air_bag_suspension/index2.html

Can it be done? For years before we started chatting up adjustable suspensions on this list. Are there going to be drawbacks and compromises? Sure, but we're going to have just as many of them trying to raise a truck 6inches from it's stock height, regardless of method. Low rider in reverse. Who says 80 owners can't do things a bit backwards?

Grab a beer, fire away at my logic and Christo's tech writeup - they appear to be very similar - his is based on experience, mine is based on working thru the concept with a beer, pen and napkin.

I believe anyone thinking they can drive their 'bag coil over' 80 to the offroad park, raise it 6inches, and believe it's going to solve more problems than it creates, ought to be joining me for beers and laughs at the lowrider parades.

No bud either, gots to grab the unpasturized Modelo.
SJ

 

[Walking Eagle]

Find the shock here:

http://lowridermagazine.com/tech/0603_lrm_air_bag_suspension/index2.html

]

No damping there by that bag. That is nothing more than a spring.

[Grab a beer, fire away at my logic and Christo's tech writeup - they appear to be very similar - his is based on experience, mine is based on working thru the concept with a beer, pen and napkin.

Doesn't apply directly. The suspension will bottom out at some point, and top out at some point. Christo's tech writeup is all about making it drive safe and right on the street after changing the ride height. If the suspesion goes from 0 (full bottomed out), to say 12" (full droop), and the ride height is set at 4, that's where the caster and such needs to be set properly. If the suspension cycles down to 12, weither it is just by "natural forces" (like the other tire being up on a rock), or due to forcing the articulation with an airbag, weither it be an airbag on a coil over or just bags, the effect is the same on all the other parts of the system. IT REALLY IS THAT SIMPLE! If I want to drive all day at 4, then go off-roading at 4, and when I reach a paticularly tall step, and jack the front end up to 10 - it's not going to really have any negative effects. At .5 mph climbing a ledge, the caster being off and having little or no return to center is not going to amount to squat.

The bennifit - you get to run around all week back and forth to work without the higher CG. You get to do 95% of your off-roading with a lower CG. The only time you have the negative of a higher CG, is when you really need it. And you can force more articulation out of the system than with just normal coils.

 

[firetruck41]

Find the shock here:

http://lowridermagazine.com/tech/060...on/index2.html

Using a piece of a shock to make an air spring does not make the air bag a dampening device . Judging by this and other threads, he will never admit he is wrong or mistaken, just distracts with other BS, hoping you won't notice his mistakes. Hopefully he won't continue this habit of spreading erroneous information and failing to correct it, even when pointed out to him.

 

[SUMOTOY]

No damping there by that bag. That is nothing more than a spring.

There is damping in the bag, there is damping in any bag. The real question is whether it can handle the frequency rate of a shock. It can't as efficiently as a shock, but it certainly can be driven without a shock. Thousands of folks do it every day. My point. The technology is moving towards shockless bags, internal valving, wall thckness and external port size makes that possible.

Doesn't apply directly. The suspension will bottom out at some point, and top out at some point. Christo's tech writeup is all about making it drive safe and right on the street after changing the ride height. If the suspesion goes from 0 (full bottomed out), to say 12" (full droop), and the ride height is set at 4, that's where the caster and such needs to be set properly. If the suspension cycles down to 12, weither it is just by "natural forces" (like the other tire being up on a rock), or due to forcing the articulation with an airbag, weither it be an airbag on a coil over or just bags, the effect is the same on all the other parts of the system. IT REALLY IS THAT SIMPLE! If I want to drive all day at 4, then go off-roading at 4, and when I reach a paticularly tall step, and jack the front end up to 10 - it's not going to really have any negative effects. At .5 mph climbing a ledge, the caster being off and having little or no return to center is not going to amount to squat.

What applies directly is Ackermann effect causing arch interference. I think you need to go thru Christos post carefully and address the points one at a time, looking at 0 to +6in of lift. No question that is out of range on the 80 application of that C/O.

The bennifit - you get to run around all week back and forth to work without the higher CG. You get to do 95% of your off-roading with a lower CG. The only time you have the negative of a higher CG, is when you really need it. And you can force more articulation out of the system than with just normal coils.

What are you doing with the bump stops? What size tires are you running. At what point does the panhard rod cause the inside tire to reduce turning radius? What about brake bias?

I think this is oversimplified without specific targets and goals. I can easily walk you thru the Ackermann Effect issues, I do it all the time in my job. I appreciate you being so patient with me WE, I suspect we agree it's possible to have variable height applied to the 80 chassis. We clearly disagree on how much is too much. You can put up all the prose you desire, but it's a simple physics or archs.



Scott Justusson

 

[Walking Eagle]

Sumotoy -

I'm done with this.

You obviously have no understanding of what an airbag is or how it works. It is no more a damping device than a coil spring. Sure you can drive with just a bag and no shock. You can drive with just coils and no shocks. You can hit yourself in the head with a hammer repeatedly, it doesn't mean it's a wise thing to do.

It's also pretty apparent you have no understanding of Ackerman Effect. "Ackerman is the difference in turn radius between the front tires." Cars are made to have the inside wheel turn in more than the outside wheel. Different ways of doing it, but since the 80 series solid axle has a solid rod running from one wheel to the other, there isn't anything in a lift that is going to change their relationship to one another! There is a ship load of stuff that is effected by lift, this isn't one of them.

It is simple physics and geometry - and suffice to say, I know more about it than you do. Maybe if you stopped drinking so much beer when you think about this stuff it might make more sense.

Ben is right - it seems you are just going to keep thowing in erroneous BS. I gave you targets and goals, you ignored them.

You win. You've proven your point, at least if that point is you can't teach someone who is unwilling to learn.

 

[alia176]

Just another observation....

If someone does indeed eliminate the coil springs (in an 80) and go with the said fancy shocks, will the factory shock mounts be able to handle the task? The task being support the vehicle's entire weight.

Sumo,
Are you using four air lift bags with the same p/n? I assume you can lift your vehicle by simply airing up the bags? If so, do you have an estimate to the amount of lift say from 5 psi to 35 psi? When I used a pair of these bags in the back of my RR, that range of psi would lift the rear end by about 2-3", depending on the cargo weight of course.

Thinking out loud, I wonder if these bags would work in a set of non oem springs. Obviously, a set of J springs will be a tad taller than the set of oem springs. I suppose, the min air press for the air bags would need to be increased to say, 10 psi just so the tops and bottoms of the air lift bags can actually reach the top and bottom springs perches. Thoughts?

Hit me off line if you'd like. I don't want to ruffle anyone's feathers!

Ali

 

[Walking Eagle]

Just another observation....

If someone does indeed eliminate the coil springs (in an 80) and go with the said fancy shocks, will the factory shock mounts be able to handle the task? The task being support the vehicle's entire weight.

Custom mounts would be required to go to coil overs.

Thinking out loud, I wonder if these bags would work in a set of non oem springs. Obviously, a set of J springs will be a tad taller than the set of oem springs. I suppose, the min air press for the air bags would need to be increased to say, 10 psi just so the tops and bottoms of the air lift bags can actually reach the top and bottom springs perches. Thoughts?

Hit me off line if you'd like. I don't want to ruffle anyone's feathers!

Ali

I've heard that the air lift folks are happy to help you find some that fit. They'll be for some other aplication - like a Ford van or super duty or something else that has tall springs.

 

[SUMOTOY]

Sumotoy -

I'm done with this.

You obviously have no understanding of what an airbag is or how it works. It is no more a damping device than a coil spring. Sure you can drive with just a bag and no shock. You can drive with just coils and no shocks. You can hit yourself in the head with a hammer repeatedly, it doesn't mean it's a wise thing to do.

It's also pretty apparent you have no understanding of Ackerman Effect. "Ackerman is the difference in turn radius between the front tires." Cars are made to have the inside wheel turn in more than the outside wheel. Different ways of doing it, but since the 80 series solid axle has a solid rod running from one wheel to the other, there isn't anything in a lift that is going to change their relationship to one another! There is a ship load of stuff that is effected by lift, this isn't one of them.

It is simple physics and geometry - and suffice to say, I know more about it than you do. Maybe if you stopped drinking so much beer when you think about this stuff it might make more sense.

Ben is right - it seems you are just going to keep thowing in erroneous BS. I gave you targets and goals, you ignored them.

You win. You've proven your point, at least if that point is you can't teach someone who is unwilling to learn.

WE,
Unfortunately, a quick google of Ackermann Effect is going to give you the most hits on turning radius, but the physics principle is tougher to find. It's acually a physics principle is regarding multiple arch effects and pivots. I'm convinced a lot of folks know more than me. I'm also convinced a lot of folks have learned about Ackermann Effect, some from BTDT, some with more experience than you or I combined. I urged you to look at Christo's post on the subject of lifting a truck. All the rod parts they sell for the 80 are a result of Ackermann Effect and correcting for it.

The relationship between the toe left to right will stay constant on a solid axle, absolutely you are correct. The relationship between the steering arm and the drag link won't be constant, so solid axle steering suffers the same bumpsteer problems as an IFS, it's just in a different plane. As you lift the axle from the frame, the drag link will drop where it attaches to the axle. As it does so, it shortens the effective length of the link, car will start to turn to the left, with no driver input. This is the definition of bumpsteer, and bumpsteer, by definition is caused by Ackermann Effect. You can correct for it to some extent for a given height, but change the height again, or further, it becomes significant again.

This also holds true for other links on the 80 as well. Swaybar, rear pinion angle due to upper control arm links, brake bias is affected, front caster is affected, and panhard rods also get shorter, causing the axle to shift toward the solid mounting pivot. All these are well described in Christo's technical post. All the 'fixes' are also offered on Slee's site. There is no doubt that the airbag c/o you pictured is going to force 6inches of lift. The question is, will the resultant Ackermann Effect, cause drivability issues, or worse. From stock to 6inches, it will, Christo even tells you exactly what will happen. What am I missing here? I proposed Ackermann Effect will be the problem of variable lift based on physics, and confirmed it from a respected 80 hardware and tech source on this very list.

Regardless of where you put the baseline (stock, +4, +6 etc), you are limited by physics on how much 'higher' you can go before you have a problem again.

I appreciate you being patient with me. You don't need to understand any physics of Ackermann Effect. You only need to print off Christo's tech post, compare it with lifting a stock truck to the 6in of max travel of that C/O, and know you will have issues. I say the issues are so big (like when you bend and break stuff), you will find 'benefit' to be an oxymoron.

I'd be happy to be educated more on Ackermann Effect, because I deal with it almost daily at my job. If we can't get agreement on what it is and it's limitations on the 80, it's tough to move the discussion forward beyond beer bashing.

To start, measure the stock drag link, rear control arm, and panhard rods. Lift them 6inches and measure again, or you can get a calculator out and measure it. Or, just give Christo a call, and ask him what the modified link measures are, I'm sure he's already quite familiar with Ackermann Effect, and didn't choose those modified lengths by trial and error.

Thanks for keeping it lively WE. It might be nice to actually close this with an agreement on what is significant in terms of baseline vs maximum lift. Without doing the math, I suspect whatever the baseline, 3inches of upward travel is pretty close to max on a dual ride height 80. Once we "Define x", this discussion might even have some worth.

Cheers

SJ

 

[Walking Eagle]

I know I shouldn't, but one more post, in case anyone other than Sumotoy is interested - the way factory air systems generally seem to be, you are limited to how fast you can go at max height.

http://www.worldcarfans.com/news.cfm?NewsID=2021007.001&Page=6/country/gcf

"Variable ground clearance from 160 to 300 mm;
automatic running-gear lowering at high speeds


The Touareg with air suspension rises and lowers automatically based on speed in “Street Level” mode, which is used primarily on-road. To optimise vehicle handling, the running gear sinks from 215 mm to 190 mm at 125 km/h. At 180 km/h, a level of 180 mm is automatically set. But the driver still has the option of setting other levels manually. The Touareg also rises and lowers automatically in “Off-road Level” mode.

Loading level: 160 mm ground clearance, up to 5 km/h
High-speed I: 190 mm ground clearance, from 125 km/h
High-speed II: 180 mm ground clearance, from 180 km/h
Street Level: 215 mm ground clearance, 0 – 125 km/h
Off-road Level: 240 mm ground clearance, up to 70 km/h
X’tra Level: 300 mm ground clearance, up to 20 km/h"

160mm to 300 mm - that's "only" 5.5 inches. Course that's also on a IFS/IRS suspension, which is more sensitive to height change.

Yep, guess the idea of running at street height and raising 5" to off road at <20kmh (12.4mph) - is purely impossible. Don't throw the computers in there as an excuss as to why it works for them, that doesn't change any of the drive parts, and isn't really necessary to just get two driver controled heights.

 

[e9999]

is this some sort of bizarre courting ritual....?

 

[alia176]

Sumo wrote:

>As you lift the axle from the frame, the drag link will drop where it attaches to the axle. As it does so, it shortens the effective length of the link, car will start to turn to the left, with no driver input.

Great, now I have to add yet another thread adjuster to the drag link to maintain it's length.

Ali