I need to soften the empty ride of my dually quite a bit. I was considering either:


1 - Install Airlift bags and remove the lower leaf.


2 - Install Primary Air or Ketterman complete rear air suspension.


I know the complete rear will cost me about $1K - $1.5K more. Is it worth it? I had the bags on my 2500HD and they helped a bunch without taking the leaf out of that but it was riding on the bags most of the time. Either way I will also put in the Auto Level system.

Hey Zeke!


I have been researching this as well. I'm gonna' install the PRIMARY AIR SYSTEM (hopefully within a couple weeks)......It seems to be the best out there, including those you mentioned!


I'm empty most of the time and I am willing to shuck out the dough if it helps my ACHING back like I think it will! (NO, Im not oldhttp://www.dieselplace.com/forum/smileys/Embarrased.gif)


I will post as soon as I get it installed.....GOOD LUCK and let us know what you decide on!

In option 1, which leaf would you eliminate? The bottom one is the overload. That will eliminate stage 2 bucking, but not otherwise soften the ride, if I am thinking correctly.





Michael

Michael;


I have pretty much given up on the option 1 as it would not soften teh ride much form what I can figure.http://www.dieselplace.com/forum/smileys/Confused.gif I am looking at Airlift Primary Air, Kelderman 4 link or Kelderman rear unit only. The rear only unit puts air bags between the leaf springs and the rear perch. It is supposed to give a "softer" empty ride than their full 4 link system. Link makes a great looking unit for Ford and all Medium trucks but no GM "light" units.http://www.dieselplace.com/forum/smileys/Disapprove.gif


The Kelderman rear system is the least expensive ($895 plus autolevel if you want). I am concerned about the twisting of the box beams in the Primary Air when one wheel is higher than the other. I have heard good and not so good about both units so I am still stuck.


eds04max;


Did you get the Primary on yet? I would like a report ASAP on installation and ride qualities. You will be the first "customer" i have spoke with on either unit.http://www.dieselplace.com/forum/smileys/Cry.gif


Thanks, Zeke

heh zeke, my concern was with the hitch twisting of the cheaper air ride from kelderman, if the bags are attached to the one piece hitch, does the hitch arm flex with the pressure of one bag being up and one being down as the axle tilts. it saids like alot of pressure to be put on a 2" square tube because it has to twist if one tire pushes up and the other drops. i might be wrong, i'm no engineer. just use to much common sense sometimes. common sense does always apply though.


john


02 3500 cc lb 4x4 lt

It would be nice to have the auto-level, and be able to tune on the fly as well.





MichaelEdited by: masterp2

Michael, no adjust on-the-fly, it is auto. (keeps truck at same ride hieght regardless of load).....I was confussed too!!http://www.dieselplace.com/forum/smileys/Embarrased.gif


Zeke, sorry dude! I'm wantin it just as bad as you are but my tax returns have been slower than expected(almost as slow as my typinghttp://www.dieselplace.com/forum/smileys/Big Smile.gif)......although, one did come in today!!! I'm shootin for end of this month!...P.M. me, let's talk tech.

Looking at those 2 systems, primary air is going to be a better ride, but I'd sure like to have a spring backup.


I just dont see a 300% benefit over $200 airbags (done right). Dump the overloads and the big removeable leaf. Mount the airbags (with a height adjusting plate if necessary) so that at 10 psi, the truck sits 1" higher than at 0 psi. You then have 1" of pure air travel before the (compliance reduced) springs begin to assist. That 1" has very low restoration force, about a 100 pounds per inch, unlike the stock springs, 1000 lbs per inch of travel. This is rough, but the idea will nee a little trial and error on the bag mounting/pressure. But I really think it would be worth it, and put the rest of the money into a tuner.

BTW, I'm not confused, I'm serious. It's just electricity.

Saw this. Not much information. Is it worth a look?


http://www.tsliftkitstore.com/product.asp?returnURL=default.asp&ID=49611

Here is a settup similar to what I will do. It will allow digital pressure readings, man-off-auto switch, and switch for manual solenoid inflation/deflation. You can have it all and no airlines in the cab if desired.


http://community.webshots.com/album/57739133AWOJCV

Check out "Velvet Ride" replacement shackles. I put these on my Ford F350 and they helped a lot. You can find more info at http://www.lordcorp.com/DesktopDefault.aspx?tabid=488.


Mike

Mike, Anything will help the F350's ride. These do not make an appreciable improvement with the GM (reported) and it ends up 1" lower.


I am doing some research on the range rovers success using air. Some of this engineering should benefit the GM. I would like to do something with a predictable result, that turns the HD ride into a cushion, without losing the payload. I know it's possible without giving up the "horse and buggy" springs.


Will post more of my conclusions as they develop.

Hey guy's in case you havn't figured it out, we are "plowing new ground" when it comes to 100% air ride (rear) so I think masterp2 is right in saying it will take some trial and error!! As I understand it, there are only a handfull on 2500 HD's nationwide with Primary Air, but it is the same kit as 3500 HD and there are many of those on the road.


masterp2, I assumed you were speaking of Primary Air being adjust on-the-fly. (we know what ass..u..me spells!!http://www.dieselplace.com/forum/smileys/Big Smile.gif) Didn't mean to imply you were confused....it appears you are well versed on the mechanics of what we are trying to do. It seems you are planning on some "slight" mod's.http://www.dieselplace.com/forum/smileys/Clap.gif


If any of you guy's have discovered a system, other than previously mentioned, I would surely want to hear about it!!!!


masterp2, I hope your right about keeping the stock leafs, but I dont think our trucks will ever really ride "GOOD" until we lose the steel springs!http://www.dieselplace.com/forum/smileys/Cry.gif

eds04max


Shouldn't be too much of a challenge to manually overide an automatic system.


Here is the thing. The airbags everyone is using as add-ons, are not designed to improve the ride, they are designed to handle weight, like fat old ucle pete sitting on a beach ball, they are more or less spherical air containers.


Here is a ride quality bag designed for the Expedition 4WD.


http://www.dieselplace.com/forum/uploads/D57_airbagcross.png


The "ride quality" air "spring" is designed to travel much further, on a convolution, before it's spring kicks in. It's spring rate is nearly constant over it's range of travel, compared to the ride-rite's or leafs.


http://www.dieselplace.com/forum/uploads/ZZA_springrateexpeditionairbag.png


The thick vert black line is the static ride displacement. Looking at a rate of change of 50 lbs per inch. No wonder I love my expedition. The ride-rite/ airlift curves would be somewhat steeper, I believe.


I don't mean to hijack this thread, I hope this information is useful for your project, I'll keep this line of thought going because I am on a roll for my own purposes/project. But I am new to the community and I have scouted many of the big truck forums, this is the most informative and intelligent, and the designer did a great job keeping the page clean


I do not think the kelderman uses this type of spring, I can't tell from the pictures. But what the Kelderman does is provide some isolation from the springs, causing the truck to ride down on the bags before applying greater force to the springs. But you are still bouncing on springs, so you are correct. But here's the thing. Isn't ride quality pretty much evaluated for the 95% of the driving we do? For most of us that is highway or dirt road conditions where spring displacement of +/- 1 to 2 inches prevails. Making the ride float for that 95% is the goal. The Kelderman probably does this very very well, though, even if using the beach ball type bags. Nonetheless, a bump must be transmitted through the spring to the trailing shackles and then to the airbag. Having the old stock springs suspend you if they go flat, makes this design my vote. And for the guy who was going to buy a hitch, it's a great value.


But I can't really tell if the Kelderman reduces "independence".. Are both sides connected, or does each side ride independent on it's own bag without applying force to the other bag? If it is independent, that makes for side-side load adjustment potential.


The range rover (4 wheel independent air) incorporates enhanced independence, the bags are interconnected with large diameter tubing. When the wheel hits an obstacle, the bag is compressed and the transferred displaced air increases spring rate on the opposite wheel (or diagonal wheel, I'm not sure). It is engineering to maximize traction on the drooping wheel, and increases articulation in off-road travel.


This is turning into more than 2 cents, but if helpful, that's the idea.





Michael

Here is a settup similar to what I will do. It will allow digital pressure readings, man-off-auto switch, and switch for manual solenoid inflation/deflation. You can have it all and no airlines in the cab if desired.


http://community.webshots.com/album/57739133AWOJCV Who's truck is this?

http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_profile;u=00006223

http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_profile;u=00006223 Thanks!

Hey guy's, I saw a Kelderman setup on a C4500 Kodiak today......looks sharp! (it's a good thing too... very visable. It hangs low.) No time for a ride, but I will see him again soon and get that test ride! Owner say's he LOVES it! I'll post after ride.


BTW...still havn't installed mine. Seeing Kelderman has me second guessing myself!


masterp2, I was "told" that these systems (bags) ARE for improved ride.http://www.dieselplace.com/forum/smileys/Ermm.gif ...........I better not get too deep here, you know more than I want to know!!!http://www.dieselplace.com/forum/smileys/Big Smile.gif..seriously, this is good info.


I agree 100% with comments about this forum...AWESOME!!

"I was "told" that these systems (bags) ARE for improved ride."


If you mean Kelderman, I agree, though I would like to see a dispacement curve (shown above) for the rubber they are using. The flatter the curve, the nicer the ride.


But the 5000 lb air rides are built for load, with a steep curve. i.e. has dramatic increase in force with displacement from rest. You know, springy, like bouncing on a beach ball. If you call up the manufacturer, they say that as well. I asked if I could improve the ride with them, they said , no, not by themselves. To mean that the leafs still operate the same way, in concert with the bags. I agree with them, that spring compliance must be addressed. Kelderman does this with leverage. The truck load interacts mostly with the bags before the "excess" is handled with stock leafspring deflection. Nice design that preserves the axle dynamic.


I have spoken to Adam at Arnott, who is interested in developing aftermarket comfort air bags using the one shown above as an alternative to the rougher air-ride. An aftermatket add-on that would greatly "float" the ride. As a minimum though, the overloads would have to be removed, for the nicest ride in a wide travel range. The overloads could be kept, if you don't mind a 1-2" lift and an occasional pogo on deep ruts. Even the Kelderman can't eliminate this if the overloads are retained.


I think the self-leveling recipe without the overloads would be the sweetest, and cheapest, if the bag above could be adapted to our trucks, yet to be demonstrated.


Just for kicks here, does anybody care about payload capabilty over 2000 lbs? (2500 lbs for 1-ton)?


I don't see the concern with any of these options.


Michael

Guys;


Take a look at the Airlift Primary Air bags at:


http://www.airliftcompany.com/PrimaryAirWeb/index.htm


They use the softer flexing sliding type of bag that the ride quality items use, I believe. They look identical to the drawing in Masterp2's wonderful tutoral above. They also have the leverage aspect. My biggest concern is the ability to twist to allow the suspension to pivot up and down on opposing sides. By this I mean that when yopu go into a hole with one side or up on a rock or parking curb with one, you need to allow the system to flewx enough to avoid stressing the members too much and causing cracking.


I spoke with Brad Matznick at Airlift, a Sales Engineer type (and fellow RV'er and nice guy as well!) and he told me straight out that it was not meant for off-roading. It is designed to take the normal type of strain that towing folks experience. I will admit that, with the exception of Surf Fishing and Scout support work I rarely take it off-road. The beach is relatively smooth (the sand gives a lot when you hit the track marks) and I take it easy on teh Scout stuff, especially as the truck is a CC LB and I just don't have good clearance with that wheelbase anymore!

I spoke with Brad Matznick at Airlift, a Sales Engineer type (and fellow RV'er and nice guy as well!) and he told me straight out that it was not meant for off-roading.


That is good to know. I had completely disregarded the non-static loads that these vehicles encounter when loaded, beit potholes or off-roading.


It is a reminder that airbags in niceriding 4wd vehicles are just a component of the suspension, and some type of metal spring is the suspension "meat". At least I think this is the case.

masterp2:


The "metal" in the Primary Air are the horozontal beams. They are designed to give a certain amount. Thay will probably not hold up to severe off-roading over a prolonged period. But that is not what they are meant for. I believe that the Kelderman works very similarly. The Link system is the most robust I have seen by far but it is much more expensive and NOT (at this time) made for our GM light trucks.


Has anyone reading this thread actually rode in a truck equiped with any of these systems and the same type of truck without them? I really want to speak with a first-hand customer!

Thought I would pass this along, possibly more options for you.





http://www.tsliftkitstore.com/product_list.asp?id=2153

Here is a spring I am considering using for airbags.


http://www.dieselplace.com/forum/uploads/141_1s6-023_charts.png


http://www.dieselplace.com/forum/uploads/6CD_1s6-023_diagram.png

Check this out


http://www.airride.com/techarticles/buildairsuspension.asp


they are referring to sleeve type bags, in ride quality applications

eds04max;


Did you get the system yet? I am looking seriously at the Kelderman 2 bag rear only now. It retains the stock leaf springs (with the removal of the top overload stops) and basically replaces the rear spring perch with airbags. You get two stage springs, a softer ride at normal heights (the airbags soak up more of the bump quicker), and backup in case of air leaks. It also costs less.


The only negatives I can figure are:


1 - Reduced height adjustment capability ( only about 2 ")


2 - They are tied together left to right by a beam, eliminating any independent load adjustment, although this gives less lean in corners as the bags shift air (I think).


3 - Lower ground clearance. How much I don't know yet.


Masterp;


Good article in that last link. Makes sense! If I remember aren't you replacing the air suspension on an Expedition? If so you are already ahead of us.


I have to ask both of you what your names mean. They make no sense to me. No biggie, just curious as I type them when answering these. Hope we get this figured out soon. Kelderman will upgrade the Autolevel air compressor to a Viair 450 so I can inflate tires effectively and perhaps get those locomotive air horns to work when I find a decent deal on them.

Zeke,


I started down this road looking for ride improvement in a 2500HD. The expedition I own prompted me to look at what made its ride so nice, yet level when loaded. Air IS the answer. But not ANY air. Sleeve type air. One of the challenges for our trucks with sleeve air is finding one with a small diameter and still has adequate load leveling capability, most available sleeve bags are much lighter duty than the "ride-rites" and "air lift" convoluted beach ball bags, which by the way, are inferior in ride quality to the sleeve bags (curve shown above), no question. The following curve is the reason why, this is the air-lift super duty.


http://www.dieselplace.com/forum/uploads/8AF_Air-lift.png


A flat curve at 100 psi is what get's you ride comfort when added to existing leaf springs, and these beach balls cannot do that. BTW, these curves represent progressive "spring rate". Great load capacity in a small package, but it is a "bucking" spring.


The comfortable big rigs use sleeve bags that can level a big load, but they are huge around.


I think I found such a bag in the Firestone F9100, 4000 lbs leveling at the bags. Any loads centered forward of the bag location can be increased from that, though I think 4000lbs total is already outside legal limits for bed load, even for the dually??? I read a post somewhere that for a 2500HD CC with D/A, the allowable bed payload was about 1500 lbs. In reality, I guess people safely exceed this. Anybody know how much weight the springs are supporting, empty, and at rest?


From what I see of the Kelderman, I like it for those that it was really designed for: Very heavy duty truck that need an over-the-road passenger comfort and a bolt on application, beit a trailer of horses or just trying to keep the coffe maker on the RV kitchen table. I don't like it at all for empty ride or off-road use. It's design inherently reduces articulation. I think the manufacturer also cautions against any heavy offroad use, it is just not designed to twist, it is designed to carry a heavy load straight ahead and do it in pure pleasure. Horses gotta love it. Also I think it might be dangerous if the bags were not interconnected. Under load, if one bag broke, you could have a serious force producing asymmetry, conjecture on my part. But as long as both bags inflate and deflate together, that is negated, but you lose any side-side control, which in my opinion is a huge advantage of airbags in the first place.


It also appears the spare will have to be moved, this needs clarification.


I will probably use an Air ride technology spring, and stay away from the disadvantages you note, plus some. I really think I will get most of the ride comfort of the kelderman, when executed properly, with a butload of advantages.


Michael

Michael;


Thank you for putting it clearly. I can finally understand! The difference in the graphs is noteworthy. I guess you want as flat a curve as possible.


A few additions for your most recent post:


1 - The Airlift Primary Air (full replacement of leafs) has the convoluted type air bags but I do not know the specifications on them.


2 - The big rigs that use the convoluted bags and get both comfort and capacity do not have to worry much about off-road use so I figure their design does not allow much side to side height variance.


3 - I believe my dually has a rear GVWR of 8600". It weighs about 3320 with just the hitch in and a half tank of gas. That still leaves me 5280# of payload capacity in the rear. Granted I will hit the total GVWR of 11,200# sooner as my truck total is about 7840# which leaves me with about 3360# payload so your 4K bags would do just fine.


4 - The Kelderman I am looking at is only the rear unit. It replaces the leaf spring rear perch (while leaving the leafs in the system) and gives both ride capacity and comfort (from what Rick Kelderman has to say) at the same time. He also told me that it is a better choice for my needs than the more expensive rear replacement that removes the leafs. Basically it rides better unloaded as you have kept the existing leaf spring rate and placed it in series with the air. The bags are not convoluted however and that is the biggest drawback.


It sounds like you are designing a new swing arm suspension with the convoluted bags. I am eager to see what you come up with and if it would help me!


OK, anybody out there who has air suspension? Let's hear from you! We need data!


Zeke

Basically it rides better unloaded as you have kept the existing leaf spring rate and placed it in series with the air. The bags are not convoluted however and that is the biggest drawback.


It sounds like you are designing a new swing arm suspension with the convoluted bags.


You WANT a sleeved bag, the drawback IS the convoluted bag, and it's increasing spring rate with increasing pressure. I don't like the convoluted bags for any ride quality application.


With the sleeved bag (nearly zero spring rate), increasing pressure makes the ride more comfortable, by reducing the overall spring rate (parallel springs) because the leaf pack is unloaded. Reducing pressure lowers the vehicle and increases spring rate, because the leafsprings (high spring rate) are carrying more of the load.


Said another way, at a given pressure, if you load it up, the suspension settles to where the leafs provide the additional lift the rig now requires, at the same time increasing the combined spring rate marginally. The beach balls do it much more dramatically (steeper curve) and reduce ride quality with load.


And this is all as it should be,


lifted=compliant=off-road enhanced ride height=ride comfort


lowered=moderately stiffer=load handling=trailer compatability


The convoluted bags turn these relationships upside down, and the empty ride benefit is limited to it's ability to (stiffly) keep the main pack away from the overloads (which we all know can be dealt with without increasing spring rate or spending money). A firestone chief engineer told me this. They also keep the arse up, obvious handling benefit. Otherwise, convoluted bags merely add to the spring rate problem that already exists in the empty stock ride.


The series relationship of the Kelderman (you hit the nail on the headhttp://www.dieselplace.com/forum/smileys/Clap.gif) make it a unique leafspring settup, and it's ride comfort is probably unmatched by anything with a parallel spring settup on a 3500, though I think I will get close with the 2500 leafs and 4000 lb sleeved bags, and retain some real independent benefits (and some cash). Simple bolt on application, much like the airlifts.


Edited by: masterp2

Michael;


I'm sorry. By Convoluted I meant the sleeved (sliding) bags. The Kelderman (both types) have the "double barrel" type of bag. I wonder if I can have them replace the double bad with the slider? That would be the best of both worlds.


Basically reverse everything I said above. So Sorry.

Yes the sleeve bag is convoluted in a sense isn't it?


I don't know what double barrel is, but the Kelderman is a sleeved or "rolling lobe" bag supplied by firestone. It is much the same design, I think, as those mounted on big rigs, just a little smaller scale. Look at the F2107 bag on this site


http://www.ridetech.com/productinfo/dimensions.asp


Exactly what the difference is between sleeve/piston and rolling lobe is I do not know, but they both have fairly flat curves with very small spring rates.


Question for anybody: How much weight sits on the rear leafsprings, at rest, empty?


Educated speculation is fine, make a guess.Edited by: masterp2

Michael;


Sorry, it' s been a long time.


My rear weighs about 3440. I figure the axle, springs, wheels weigh about 500 total. That leaves about 2900 on the springs. But then I need something that will take an additional 3000-4000 pounds (Fifth Wheel).


Has anyone put one of these systems on yet? I am still saving the $$ up.

I have had a lowered crew cab dually ,dropped with bags from Ekstensive in Houston. The truck rode great and pulled a trailer well. I now have an 02 GMC CC dually that the ride empty stinks, so I am also considering these systems. Seen then all but has anyone installed them. Want to keep the ride height almost stock and not lower the truck it still needs to be used . Thanks