Air bags and auto leveling

[Hummin Cummins]

I agree Bob, I didnt notice any difference with my old bags at the minimum pressure. Not sure why there is a minimum needed unless they are worried about wrinkling causing weak spots from losing their shape.



Mike, My only concern would be that if I dump them to unhook, and then unload the truck, unsure as to if they would return to the factory minimum pressure or if the springs would carry the weight and the bags not fill at all until I was loaded again. Trial and error I guess. I'm mounting the compressor and tank in my tool box, would be a great place for the dump valve also. Less plumbing. Keepin it simple

 

[NIsaacs]

The plan is to maintain the minimum psi in the bags for empty ride height and when loading the 5er, bags "should" automatically inflate to raise the truck back to the original ride height.

Chris, thanks for the explination, good writeup. I think the above quote is what kept me asking questions. I never figured you wanted the bags to inflate more than level with a load. To raise it to orginal ride height would include the built in rake of the truck.



Nick

 

[JPul]

I am still missing something here. I understand the compensation that the bags provide for a loaded truck and I understand how the leveling system works. I am putting a Lincoln MK7 air ride system on my 55 ford pickup so I've studied this, but in the case of my 55, this is the only suspension system. In the case of our hauling pick-ups its intended to be a suppliment. Here's where I have a problem.



The system is setup to maintain a level ride with a load in the bed or on a hitch. When that load is removed, the truck bed rises, the leveling system releases air to drop the truck back down, but the empty height with just the stock suspension sits higher than the level height desired for the loaded truck so the system can't bring the truck back to level, will release all of the air to try to get to level, and you now have empty bags which is not desirous.



Is there some kind of an override here that maintains that minimum air pressure and how is that pressure sensed.



Regards, John

 

[JHumphries]

I believe the idea is, the auto-level valve is set with minimumm air pressure in the bags, and the truck on level ground.
As they truck is loaded, the bags will inflate to keep that ride height, meaning it will still have the factory rake, unless a front leveling kit has been installed.
When the load is rmoved, the truck will still be at factory ride height, rake and all.

The end result is what ever height and rake the truck is at when the valve linkage is adjusted, the truck will always stay there unless the bags can't air up enough to raise it any more, which would be a lot of weight!

 

[NIsaacs]

As they truck is loaded, the bags will inflate to keep that ride height, meaning it will still have the factory rake, unless a front leveling kit has been installed.

See, thats my issue. You don't want that. You want the truck to come down level, then add air if needed to hold it there. I also don't recommend a leveling kit if you are going to haul heavy.



Nick

 

[MelvinPierce]

I am not sure if you will like the auto level. I have a trucking company, and have far too many miles with full air bags to want to remember!

I have air bags on my Dodge. I have a switch and gauge in the pickup. I set it at 10# empty, to keep some air in the bags, as required by OEM.

I have a large 42' toyhauler, Voltage. When I hook up, the pressure goes up to 45-50# as the truck squats. All by itself, I add no air.

At first, I thought I would want to return the truck to level, just like on my Peterbilt air system. I measured the bumper ht. prior to hookup, and put in enough air to return to that ht. with the trailer on. I had to air up to 110#. the air bags were hard as rocks, and when I towed, you could feel all the bumps! As I thought about it, I realized I was carrying all the wt. of the trailer on the air bags, and the springs were only carrying what they did when the pickup was empty.

The way I do it now, is I air it up to 60# with the trailer hooked up. The rear of the pickup settles some, but not all the way. The springs are carrying most of the load, and the air bags are carrying the "overload". The rear of the pickup settles about 1/2 as far as without any air at all.

It now rides real well. The bags are not so full, so they can still flex with bumps. Ride is good. I think if you use auto level to bring the truck back to original, or near original ht, you will not be happy.

I thought, before this trial, about the auto level. Would NOT do it now. It takes about 5 seconds to put in enough air to get to 60#. How many times a day do you hook up, that you cannot spend 5 seconds to put air in? Less than that to bleed it out when unhooking.

 

[mwilson]

I am not sure if you will like the auto level. I have a trucking company, and have far too many miles with full air bags to want to remember!



I have air bags on my Dodge. I have a switch and gauge in the pickup. I set it at 10# empty, to keep some air in the bags, as required by OEM.



I have a large 42' toyhauler, Voltage. When I hook up, the pressure goes up to 45-50# as the truck squats. All by itself, I add no air.



At first, I thought I would want to return the truck to level, just like on my Peterbilt air system. I measured the bumper ht. prior to hookup, and put in enough air to return to that ht. with the trailer on. I had to air up to 110#. the air bags were hard as rocks, and when I towed, you could feel all the bumps! As I thought about it, I realized I was carrying all the wt. of the trailer on the air bags, and the springs were only carrying what they did when the pickup was empty.



The way I do it now, is I air it up to 60# with the trailer hooked up. The rear of the pickup settles some, but not all the way. The springs are carrying most of the load, and the air bags are carrying the "overload". The rear of the pickup settles about 1/2 as far as without any air at all.



It now rides real well. The bags are not so full, so they can still flex with bumps. Ride is good. I think if you use auto level to bring the truck back to original, or near original ht, you will not be happy.



I thought, before this trial, about the auto level. Would NOT do it now. It takes about 5 seconds to put in enough air to get to 60#. How many times a day do you hook up, that you cannot spend 5 seconds to put air in? Less than that to bleed it out when unhooking.

Well written Mel.



Mike.

 

[NIsaacs]

Well written Mel.



Mike.

I agree, very well written.



Nick

 

[JJPage]

I am not sure if you will like the auto level. I have a trucking company, and have far too many miles with full air bags to want to remember!

I have air bags on my Dodge. I have a switch and gauge in the pickup. I set it at 10# empty, to keep some air in the bags, as required by OEM.

I have a large 42' toyhauler, Voltage. When I hook up, the pressure goes up to 45-50# as the truck squats. All by itself, I add no air.

At first, I thought I would want to return the truck to level, just like on my Peterbilt air system. I measured the bumper ht. prior to hookup, and put in enough air to return to that ht. with the trailer on. I had to air up to 110#. the air bags were hard as rocks, and when I towed, you could feel all the bumps! As I thought about it, I realized I was carrying all the wt. of the trailer on the air bags, and the springs were only carrying what they did when the pickup was empty.

The way I do it now, is I air it up to 60# with the trailer hooked up. The rear of the pickup settles some, but not all the way. The springs are carrying most of the load, and the air bags are carrying the "overload". The rear of the pickup settles about 1/2 as far as without any air at all.

It now rides real well. The bags are not so full, so they can still flex with bumps. Ride is good. I think if you use auto level to bring the truck back to original, or near original ht, you will not be happy.

I thought, before this trial, about the auto level. Would NOT do it now. It takes about 5 seconds to put in enough air to get to 60#. How many times a day do you hook up, that you cannot spend 5 seconds to put air in? Less than that to bleed it out when unhooking.

This is my approach also, except I use 25 lbs before hooking to my toy hauler. I also modified how my overloads enter the equation, this way the bags are not carrying the entire load.

 

[Hummin Cummins]

Spoke with Hellwig tech support yesterday, asked them about our thoughts on this. Was not very impressed with the lack of information I recieved. It's simple logic actually and it seems we are correct with our theorys and experiences. The way i see it with the auto leveling system is you have two choices, neither of which I like.



1. Charge the bags with the minimum recomended pressure, set the linkage for the leveling valve with truck empty. When loaded it will inflate back to empty ride height. Rear too high, will ride extremely rough, no weight on the springs. Not good.



2. Charge the bags with the minimum recomended pressure, hitch into the 5er, inflate the bags to the desired loaded height, set the linkage for that position. That will maintain level stance and good ride when loaded, but when empty the bags will totally delfate to empty. No minimum pressure maintained, warranty voided. Not good either.



I think my best option is back to my original idea of a regulator knob and gauge in the cab, Turn knob to adjust pressure, can be done on the fly. Deflate with the knob when empty. Would work the same as a dump valve to deflate for unhitching. Simple and foolproof. Only drawback I see with this setup is having to run airlines into the cab. They dont make these interiors modification friendly anymore. I could save some hassle and mount it all in the toolbox, but I really would like to be able to let the feeling of how the truck is riding loaded on the highway dictate how I adjust the pressure.



JJ, I know exactly what you mean about the overinflating. I tried the same method with my 95. Had the bags at 70+ lbs where it looked good, but every expansion joint in the road would rattle my teeth. It seemed like 50 - 55 lbs worked real well.



Looks like I will most likely go this route.

http://store.gaugemagazine.com/14airliftsinglegaugeswitchpanel.aspx

 

[seafish]

You can also look into the Smart Air Remote controls by AirLift--no need to run air lines into the cab--- It also has TWO psi presets in memory for commonly used pressures.

http://www.summitracing.com/search/...wirelessair-remote-air-suspension-controllers

AirLift has been making quality air suspension components for a long time, since 1949, and they have good customer service, answering my questions even though I was going to be buying their system used.

http://www.airliftcompany.com/

There is also a $100 manufacture rebate through Feb 28.

While I have NOT yet used this system, I DO have it waiting in my garage (got a good deal on it used) to control the Carli Long Travel air bags that I eventually plan to install.

While they also make an auto leveling kit, I chose to got htis route for the very reasons you guys are talking about... . user control.

 

[surfbeetle]

There is a lot of great info on this thread. A couple of things that I think have been overlooked. While it's important to have the truck relatively level, it's equally as important to not raise it so high that your trailer is at an odd angle. Too high or too low on the trailer will cause too much weight to be placed on only one of the axles on the trailer. You really want the trailer level to prevent that. Also with my truck, what initially led me to install airbags was the ability to adjust the height when towing because my fifth wheel caused the truck to squat to the point that I was getting vibration in the driveshaft due to the angle. With the bags I raise up the rear of the truck just enough to resolve that issue while still maintaining the proper level of the trailer. I don't have the auto controller for ride height, I have the Air Lift bags and controller that automatically keeps 10 psi of air in the system at all times.

 

[JHumphries]

See, thats my issue. You don't want that. You want the truck to come down level, then add air if needed to hold it there. I also don't recommend a leveling kit if you are going to haul heavy.

Nick

As long as you're always moving the same trailer, this might be an option. It's a dual ride height valve. By supplying air pressure to the fourth port, it changes the neutral position of the valve.
If you look at the chart on the file, with a 3 inch long arm coming out from the valve horizontally, that results in a 2 inch drop in ride height.

It's designed for city buses and such that kneel when the doors open, but it could work for a truck as well.
If you had full air ride, you could connect it to the door switches to drop the truck when you open the doors.