Air ride!

[HMS_Beagle]

I just installed an airbag suspension on my new '15 F350 dually and took it on the first camper trip. I will put at the end of this post the reasons for doing it to save the long narrative for those interested. This is from Autoflex in Canada.

Box arrived, forklift unload - it is 380 lbs of stuff:



Like Christmas in Summer, opening and unpacking:



The kit is quite complete including all parts necessary, air compressor, controls, etc., nicely labeled:

[HMS_Beagle]

I think front air is possible. Kelderman makes a front air system for the 4WD, the problem with the 2WD that I have is two fold: There is less room for the bags so you need high pressure (smaller diameter) bags, and the twin I beam mounts the springs or bags inboard with some leverage, so more bag capacity is needed even than the rear. Some guy built his own on the truck forum, and he said it worked very well until the truck got stolen!

The bags for my rear system are around $150 - less via internet discounters.

[Kayteg1]

HMS Beagle wrote:


I suspect more of the reason we don't see these on pickups is it costs more (because you need a control system and air source) and it requires a little more knowledge in care and maintenance. Air ride is becoming quite common in passenger cars and SUVs.

Air ride become very popular on luxury cars over 10 years ago.
Your system has the advantage of using commercial airbags with build in stops.
When air froze on our Mercedes wagon, the computer without telling what is it - start flashing emergency messages on dashboard to stop driving.
The system is superior for ride, but air bags have about 10 years life expectancy and rebuilding the system at dealer will go over $5,000.
You can figure out why a buyer who bought 8 years old Mercedes for $6,000 hate the system, but the guys who put 30 height tires love it as you don't want to ride on skinny rubber with steel struts.
I only hope I will live long enough to see air suspension coming on pickups from factory. Including front that is as I read from the review that with rear air, front suspension on empty pickup can still give you headaches.

[SoCalDesertRid1]

HMS Beagle wrote:

travelnutz wrote:

Only major issue I see with cantilever air ride systems and removing the OEM springs (while there's many good points) is in a bag etc quick failure, there's no backup support system at all and it can have very catastrophic results for control loss.

Actually it will just come down on the bump stops, better than breaking a spring which will lose control of the axle.

I suspect more of the reason we don't see these on pickups is it costs more (because you need a control system and air source) and it requires a little more knowledge in care and maintenance. Air ride is becoming quite common in passenger cars and SUVs.

As far as the multi-link suspension, whether it be a coil sprung or air sprung system, multi-links have been used on the front ends of cars, pickups, vans, suv's for many years.

The front end is a higher stress location for a multi-link suspension than the rear end is, due to the factors of weight transfer and side forces when steering and braking, which the rear end doesn't experience nearly as much. Yes, if some link point of a multi-link suspension fails, it can be catastrophic.

However, the OEM's have proven they can handle the stress factors and design multi-link front ends that work safely and reliably. Whether it is sprung by coils or air bags really doesn't matter much.

All that said, I still prefer the simplicity of a straight axle, leaf sprung Hotchkiss suspension design, front and rear, for heavy duty truck applications.

[HMS_Beagle]

travelnutz wrote:

Only major issue I see with cantilever air ride systems and removing the OEM springs (while there's many good points) is in a bag etc quick failure, there's no backup support system at all and it can have very catastrophic results for control loss.

Actually it will just come down on the bump stops, better than breaking a spring which will lose control of the axle.

I suspect more of the reason we don't see these on pickups is it costs more (because you need a control system and air source) and it requires a little more knowledge in care and maintenance. Air ride is becoming quite common in passenger cars and SUVs.

[Reality_Check]

LMAO... where do folks come up with this stuff?

Makes great reading for sure.

[travelnutz]

burningman,

Hello, is anyone there? My post clearly stated on "HD production pickups". Not one word about Class 6, 7, or 8 truck rigs!

[burningman]

I disagree with the comment that safety or reliability is why OEMs don't use airbag suspension.
Have you looked under a Peterbilt? Most real trucks do ride on factory air suspension.

If your airbag overloads give you sway, my first question is whether your left and right bags have separate, isolated air supplies.
If your shocks are good and you've got a rear sway bar and air bags, you should be fine.

[jimh406]

dirtyhandz wrote:
I know my air bags made my truck pretty unstable and really would sway.

You need extended bump stops and/or less air in the bags. In any case, the point is that airbags don't necessarily equal unstable or sway.

[travelnutz]

Well, on my GM HD trucks (2500HD and 3500 HD), where the airbags pushup on is NOT remotely a weak area in the truck's frame as it's the same thickness, depth, and cross section all the way and is straight horizontally and very strong. Unlike some other brands of pickups which do have weaker area designs around the rear axle area. One brand of pickup rocks side to side so much more due to frame design and where airbags must and can be mounted and can even be somewhat dangerous with high PSI in the bags in high cross winds or fast cornering. Witnessed it at the proving grounds! A TC's weight and mass is almost entirely on the truck vehicles way above the truck's rear frame, suspension, wheels, and tires and usually the weakest one of these factors is the first to fail which isn't very humorous when it occurs. Wind resistance when at highway speeds only intensifies the vehicle's stresses and bad actions in a failure. Proceed very carefully and weigh the risks when altering an OEM designed and certified thru countless hours of proving ground testing vehicle! You life and your passengers lives may well depend on it.

My OEM springs are still on as they should be and take any side to side rocking out so that's not an issue at all with our over 11' floor length very heavy fully optioned out Lance TC. Tag on the Lance says it's weight is 3842 lbs with full fresh water tank and 60 lbs of propane. No cargo. None of my truck's individual components are loaded over their individual certified GWR's or load ratings as that's key!

Rides great and handles excellent and has for nearly 80,000 miles now of travel with the heavy Lance TC on the 2500 HD truck enhanced to 3500HD OEM specs and has the Air-Lift Systems 5,000 lb capacity airbags. I know the truck and frame very well and it's real capacities as I was involved in some components on it during development back in around 2000. Same exact frame as on the 3500 HD SRW and the 3500HD DRW truck!

Adding the airbags to a GM HD pickup dampens the transferred road shock action of the metal springs while the wider spaced metal springs carry the majority of the cargo load and resist rocking.

Only major issue I see with cantilever air ride systems and removing the OEM springs (while there's many good points) is in a bag etc quick failure, there's no backup support system at all and it can have very catastrophic results for control loss. One main reason it's not used as an OEM design for HD production pickups. However, the truck's owner can make changes as long as he's staying within his registered (in some states) weight and/or is not used for hire to carry persons etc.

[HMS_Beagle]

The only dirt road I have done is my driveway (which is about 1/4 mile long). Judging from hitting service station and parking lot ramps at an angle, the rear articulates better than it did with the springs.

I had a Hellwig Bigwig rear (and front) antisway bar on there, that cuts down a lot on the freeway sway and body roll, as well as the sideways rocking when hitting ramps. I had to remove it, because the links they supply do not sit in the same place as the factory links. I put the spindly stock one back on, but the sway has returned to about what it was before with the stock bar - maybe a little better.

Most airbag assist kits these days mount under the frame between frame and axle. This is closer to the center line of the vehicle than the steel springs, so to the extent that they are carrying any load you are reducing your roll resistance by that amount. On this kit the air bags are where the springs were, as close to the tires as they can get. For the same spring rate, they should have the same sway/roll resistance. According to Firestone specs on the bags, the spring rate is a bit less than the steel springs without overloads engaged, and less still than the spring+overload. However the air bags are considerably more progressive. From that information I expected a bit more body roll and sway with the air bag suspension, but it seems about the same with the same bar. I am going to fab some links to put the Hellwig bar back on when I get time.

Travelnutz - good on ya for knowing the difference - I emphasized it because many people get the two confused. With this system you are not just replacing the springs, but also the linkages, an important factor because axle position and pinion angle are better controlled than with leaf springs.

SoCal - I have not liked air bag assist kits for the reason you describe, and the one I mention above. Also they reduce suspension travel a significant amount in many installations. If you return the truck to the same ride height it had empty after loading a camper, the whole load of the camper is carried on the air bag assists and the weak part of the frame.

[dirtyhandz]

Have you had the truck and camper on any forest or dirt roads? Wondering how the air ride handles off camber and rougher roads/trails. I know my air bags made my truck pretty unstable and really would sway. But that was just the air assist bags, this is a totally different beast.

[Kayteg1]

Since that become also educational topic, I would add that air springs and air bags (aka assist bags) are different animals.
They both use air, but with different principals.

[travelnutz]

HMS Beagle,

I'm fully aware of what your air ride system is and what airbags are. I had been doing pickup, van, and SUV component design and engineering for nearly 40 years before I sold my engineering company and finally retired. The main thing in the air ride systems is the ability of using the contained/captured compressed and compressible air pressure to greatly lessen the transferred shocks and jolts created by road imperfections and unevenness in vehicle suspensions to the occupant's bodies while giving all the needed suspension support required. All done with PSI inflation which is always available rain or shine, -30 F or 130 F virtually anywhere on the planet Earth. Air is free! Nothing even compares to compressed air's functional ability in actual performance vehicle ride quality. Nearly zero recoil action when done right and can almost negate the need for shocks being needed.

Air-Lift and other like inflatable stand alone airbags are an important fully adjustable assist to OEM conventional suspension systems. They can be inflated to become a low assist factor all the way to being the major support factor to the point where the OEM spring support could actually be removed and another alignment axle tie in management system installed. Basically, none of this is really new and it was first developed and used nearly 90 years ago. Cantilever arm type airbag suspension is ages old and can be excellent when done right. Just requires a lot more bracketry and expense to alter to and adds a lot more weight unless the OEM springs are totally removed. Lots of trade offs! Yes, I do like your system and setup and should have nice results.

[SoCalDesertRid1]

I like that the full air ride suspension kit you used uses the truck's original spring hangers and places the load fully on the hangers, which is where the truck frame engineers intended the load to be placed.

With the common add-on air-assist bag kits (Firestone, Air-Lift), they take load off the springs and place it in the middle of the frame, which is where the frame is weakest, particularly with '99-up F250-550 truck frames.

There is a half-circle scallop removed from the lower flange of the frame channel, above the axle, to allow for shock clearance. The scallop is so deep that there is practically no lower flange left on the frame in that area. That is where the frames crack.

That scallop is the same spot that the air assist bags place their additional stress on the frame.