weight distribution and air bags?

[OregonIan]

Hi all,

I installed some Firestone Ride Rite air bags on my 2010 Tundra TRD, which carries a 2000 Hawk shell. The shell has a furnace, heavy old school battery, a counter/sink, and benches built in. Not sure how much it weighs--not as much as a fully pimped out Hawk, but not as light as a basic shell. I'm guessing the Hawk will stay on the Tundra full time during summer, and take it off for winter. But I might decide to just keep it on year round.

I drove the Hawk on the Tundra for a few months without air bags, and it was pretty clear that the driver's side was lower than the passenger side, by a couple inches. This makes sense, given that the propane, furnace, counter, sink, and battery are on the driver's side. I tried my best to counter-balance the lighter passenger side by placing water on that side (usually carry 40 liters), and placing kitchen gear and personal gear on the passenger side when driving.

My question is...now that I have air bags, how important is it that I try to distribute the weight evenly? I can compensate for an uneven truck by blowing up the air bags more on the lower side. But does this solution have safety/performance drawbacks? Should I still try to distribute the weight as evenly as possible so there is less difference to compensate for?

I suppose that eventually I may get a lighter lithium battery, and/or even move the battery to the passenger side. But kind of hoping that I don't have to do that.

Thanks in advance for any wisdom. This is such a helpful group.

Ian

 

[ri-f]

Ian - airbags, as you've have implied, give you the option of distributing your weight the way that makes sense for you, based on your interior design, weight distribution and ergonomcs. But you are still masking the fact that one side is possibly a lot heavier the the other. The airbags will help compensate for the way you distributed the weight. It won't change the actual distribution but it will raise or lower a side to compensate. With airbags you might fill the port side at 85 psi and the starboard side at 20 psi, for instance, to compensate for a heavily loaded port side. This won't stress out or max out you airbags. When you're only talking about an inch or so difference in height, from side to side, or forward/aft, before deploying the airbags it's not a big deal (there capable of a stabilizing few thousand pounds), but you're counting on them to stabilize your rear end in sharp turns and reduce spring wear and tear and also bottoming out, and when you're getting close to the limits of what they were designed to do then I would think that trying to help them out a little, by balancing your load, within reason, so that your airbags are somewhat closer to evenly split on each side, would ultimately be better than working one side toward the max psi while the other is at a low psi. I don't know what the results showed when Firestone stress tested their Ride-Rites to the limit, but as in most things, keeping below red line levels will likely reduce the potential for excessive wear and tear. I think the biggest mistake with airbags is the illusion that they will compensate for limited payload capacity.

My Ride-Rites (complete kit) automatically redistribute the psi to either side and assist in leveling the load. Having the remote control option on the Ride-Rites, along with the manual valve fills is a nice option to have. Once I have initially set each airbag up, on a level surface, I never have to touch them again unless I want to radically redistribute weight or remove the camper, which I don't tend to do. And I don't sweat the small stuff, like worrying about whether the difference in the weight between an AGM or lithium battery could be an issue. Or whether having a 5-gallon jerry can on one side and not one on the other side of the rig would throw things too far out of balance. Just load your rig within reason and the airbags will compensate for the rest. They work great and I barely notice that there is an unevenly distributed load on the flatbed, even on curvy mountain roads. I've got a Hawk shell on Cummins 2500, on a flatbed platform, so for me the payload is not an issue to begin with; it's just the weight distribution that I'm trying to level out, which is why I like the Ride-Rites, which I run at about 65/40 psi, based on how I built out my rig. Clearly, I'm not running them at their max, but I'm also not running them with even pressure on both sides and I have noticed no adverse issues to date. I had to compenensate for about 1.5 inches (port/starboard) and a very modest amount forward/aft. The original rake of my rig without a load is approximately 1.5-2.0 inches higher in the rear. With the camper on and loaded, the front and rear are now exactly level, as are both sides. On a side note, it took me a while to get used to hearing the airbags at work, especially on an otherwise very quiet night. They are sensitive enough that when the air temp gets cooler or hotter, the psi will change and they will inflate/deflate to compensate. Or when I step in or out of the camper it will simply make the adjustment to get back to level.

Rich

 

[camper rich]

Just because you can level your truck with airbags doesn't mean that you have shifted (redistributed) the load. You have merely raised it up.

 

[rando]

Just because you can level your truck with airbags doesn't mean that you have shifted (redistributed) the load. You have merely raised it up.

Good point - airbags don't move the load at all, or improve the weight distribution, they just adjust the spring rate to change the height.

Toyotas do tend to lean to the drivers side without any load (driver, battery and petrol tank are usually on that side), the camper is just increasing this. I wouldn't be too worried about it.

I usually have about 25 psi in the DS air bag and 15-20 psi in the passenger side and that keeps me pretty level. Knowing what pressure you are using to level will give you some idea of the weight imbalance. If you are using higher pressures in the air bags, you may get a better ride with new springs appropriate for the load. With the Old Man Emu springs they normally come with a '+' spring for the drivers side and a '-' spring for the passenger side, which levels things out.

 

[Wallowa]

Little confused....I level my front and back wheel wells [nominally 35"] by adjusting the RideRite air bags and yes left normally is at about 34 psi and right at 26 psi to attain level...

My confusion is if you level my Tundra with a load and it "assists" the leaf springs in doing so, why does that not also adjust the sprung weight?

Ps...Biggest assist to stability has been my Hellwig rear anti-sway bar...easy to install and greatly helped handling and stopped swaying during abrupt changes of direction..





2000-2006 Toyota Tundra 2WD and 4WD - Addco 2181 Rear Anti-Sway Bar (1" Diameter)

[SIZE=.8em]Model:[/SIZE][SIZE=.9em]2181[/SIZE]

 

[rando]

The 'ride height' is determined by both the load and the spring rate, which is a measurement of how stiff your springs are. Adding air bags is increasing the spring rate and does not change the load.

Spring rate is how much a spring compresses for a given load - measured in N/mm in normal units of lbs/inch in 'freedom' units. Adding the air bags doesn't change the load part of the equation, which is determined by the mass of the camper/vehicle and its location, but it does increase the spring rate. With the increased spring rate of truck springs + air bags the suspension doesn't compress as much for the same load, reducing how much the back end squats and the increasing the height of the wheel wells. The load on each wheel is essentially the same with or without airbags, as you haven't changed the weight or weight distribution.

 

[Wallowa]

So the springs + air bags do not support the load? Or load distribution?

 

[rando]

So the springs + air bags do not support the load? Or load distribution?

The springs + air bags support the load, but they don't change the load or the load distribution.

 

[fuzzymarindave]

The springs + air bags support the load, but they don't change the load or the load distribution.

This!
I had assumed that the OP was asking about redistributing the heavy items in the camper from drivers side to passenger side.
I would say go for it where reasonably possible. A 2-inch lean is a lot and sounds like weak leaf springs.

 

[BBZ]

F150 is the same.. gas tank on left side and left side always a little lower naturally.. wish FWC had the option of putting stuff on the right side of the camper..

I run about 20 psi more in left side to account and it levels it out nicely.. and try to load camper on the right side as much as possible..

 

[rubberlegs]

I thought the left-lean was because of the road camber on two lane roads. Don't want coffee to spill. <grin>

I have no explanation for bigger roads, though.

 

[UmkaAndHawk]

Just chiming in here to add another statistic to your review.

I have a nearly identical issue, nearly identical truck, nearly identical DIY updated Hawk Shell and I was specifically instructed to just level with the airbags. I measure from hub to wheel well on both sides. I end up with only 5 to 10 pounds PSI more on one side (even less, often).

As many have stated, this is doing nothing for your load distribution! Impacts, inertia, everything are more severe on the (driver's) side with more mass; all we've done is change the spring loading (the spring constant K, in a damping equation). This means the ride will be different from one side of the truck to the other, (there's a big, stiff frame in there, so neither of us are going to notice, I'd bet).

I am keeping all this in mind when going off road, but other than that, I'm fairly confident we're safe and doing what we can to ensure long life of our vehicle and camper.