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Open Roads Forum  >  Truck Campers

 > Leveling with air bags correctly

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ajriding

st clair

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Posted: 04/18/19 02:03pm Link  |  Quote  |  Print  |  Notify Moderator

After reading forums I did what they said. I think all that I have read have been COMPLETELY wrong.
I don't mean to offend anyone, and I'm sure maybe this was mentioned already buried in long strings….

Your truck is meant to be loaded, and this is why the rear sits high when the bed is empty.

When you load your truck the rear (rear bumper) will drop lower, BUT ALSO the front will drop lower too since some of the weight is on the front also.

Some folks are all saying measure your rear bumper off the ground when unloaded and then to inflate the air bags so the height is back to that original measurement after you load the camper.

THIS IS SO WRONG.
DO NOT USE THIS METHOD.

This method actually made my front end caster out of whack and I was getting uneven tire wear.

As mentioned, the front of the truck most certainly sagged down from the weight of the truck camper, so lifting the rear back to the original measurement was not only wrong, but exacerbated the problem because the front had sagged a little so the truck angle was even more pointed down than it was unloaded.

First measure both the front and the rear to get a difference between the two.
Example, the front is 15 inches and the rear is 17. The difference between the two is 2. Don't worry about the total distance from the ground anymore, just this difference.

When you air back up you will be looking for a front to rear difference of 2. Your ground distance may or may not be the original 15 and 17, this is fine since there is weight on the truck - reason being that the front is lower. It could be 13 and 15 now instead of 15 and 17.
On top of this you may want the truck rear to sag a little bit since this is how the truck is intended to be when loaded. The manufacturer intended the truck to sit lower when loaded than when unloaded, how much I do not know.
Maybe the truck is not meant to sit at the same angle when loaded as it is when empty.

On mine if I have a 2 inch front to rear difference then when loaded I will make it a 1 inch difference instead.
There is no science to this, it is just a guess and I am sure well within parameters of the truck.

Side note: on TCs you should use the air bags that sit under the frame (on top of the leaf springs or inside the coil springs) and never the ones that sit/mount inside the frame rails. Adding spring support inside (closer to center) will make it more unstable since you are supporting the load closer to the center than it is when loaded on the stock springs.
The "inside the frame rails" bags typically use the bump stops as mounts. These are fine and dandy for towing where the extra weight is a trailer placed on a ball hitch in the center of the truck, but not for tall heavy loads in the bed.

JIMNLIN

Oklahoma

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Posted: 04/18/19 02:24pm Link  |  Quote  |  Print  |  Notify Moderator

Don't assume what didn't work for your truck won't work for others. Too many variables.
Not all TC's add weight to the trucks front axle.
And a host of other differences.


"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers

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Homeless by Choice

North America

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Posted: 04/18/19 02:57pm Link  |  Quote  |  Print  |  Notify Moderator

JIMNLIN wrote:

Don't assume what didn't work for your truck won't work for others. Too many variables.
Not all TC's add weight to the trucks front axle.
And a host of other differences.



Well, if they don't then your camper CG (Center of Gravity) is too far rearward and that is not good.
LeRoy


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twodownzero

NM

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Posted: 04/18/19 03:26pm Link  |  Quote  |  Print  |  Notify Moderator

ajriding wrote:


This method actually made my front end caster out of whack and I was getting uneven tire wear.


Caster does not contribute to tire wear. Camber and toe both have some effect. Caster is for suspension stability only; generally more is better up to a point.

I personally put air in the bags until my truck is level or close to level. It has a leveling kit on it so it's slightly taller in the rear at ride height but not as pronounced as it was factory.

You can eyeball this; no need for a tape measure at all. As the load changes, you can adjust.

There's also more to airbag use than ride height. I've noticed my truck handles better with more weight on the springs. If I crank up the airbags too high, the springs just aren't able to do their job.

S Davis

Western WA

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Posted: 04/18/19 06:53pm Link  |  Quote  |  Print  |  Notify Moderator

twodownzero wrote:

ajriding wrote:


This method actually made my front end caster out of whack and I was getting uneven tire wear.


Caster does not contribute to tire wear. Camber and toe both have some effect. Caster is for suspension stability only; generally more is better up to a point.

I personally put air in the bags until my truck is level or close to level. It has a leveling kit on it so it's slightly taller in the rear at ride height but not as pronounced as it was factory.

You can eyeball this; no need for a tape measure at all. As the load changes, you can adjust.

There's also more to airbag use than ride height. I've noticed my truck handles better with more weight on the springs. If I crank up the airbags too high, the springs just aren't able to do their job.



One thing you don't want to do is unload your springs with the air bags no matter what height the trucks rear is, I always load up and then set the bags so the overloads just start to engage.

wnjj

Cornelius, Oregon

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Posted: 04/18/19 10:32pm Link  |  Quote  |  Print  |  Notify Moderator

Homeless by Choice wrote:

JIMNLIN wrote:

Don't assume what didn't work for your truck won't work for others. Too many variables.
Not all TC's add weight to the trucks front axle.
And a host of other differences.



Well, if they don't then your camper CG (Center of Gravity) is too far rearward and that is not good.
LeRoy

Trucks are designed to haul weight on their rear axles. There’s nothing wrong with keeping the same or even losing some front axle weight,

burningman

Seattle, WA USA

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Posted: 04/18/19 10:36pm Link  |  Quote  |  Print  |  Notify Moderator

You can’t make general “no one should do this” rules from a single (and unusual) case study.
Most large truck campers do not squat the truck’s front end. The center of gravity on large campers is almost always very near the rear axle. You can call that “wrong” but it’s a fact of life.

I’m not sure why your truck’s front end sags so much, that’s not the normal condition when carrying a camper. I have had many different truck and camper combos over the last 30 years, and none of mine have ever had the problem yours does.

Even if that really was true, you could simply dial in a little more caster in your front end, depending on what type of suspension you have. It’ll drive nicer on the freeway.
Your biggest misconception may be that everyone else’s truck has the same sort of suspension.
Some have double A arms. Some have a four link. Some have leaf springs. Some have torsion bars and some have coils.

A couple degrees of caster isn’t going to chew tires up unless it was way off to begin with. If I have to guess, I’d say you have a twin-I-beam Ford? If so, that’s your biggest problem with your front suspension. Those things are always terrible for alignment and tire wear, by the very nature of their design.

Something you’re not mentioning is headlight aim.
A truck that squats in the rear ends up shining it’s headlights into people’s eyes.

It sounds more like your front springs are too soft.


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JimK-NY

NY

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Posted: 04/19/19 07:23am Link  |  Quote  |  Print  |  Notify Moderator

burningman wrote:

.......
Something you’re not mentioning is headlight aim.
A truck that squats in the rear ends up shining it’s headlights into people’s eyes....


Absolutely. My truck sagged so badly in the rear that headlights blinded oncoming traffic. Cars were frequently flashing their lights at me believing I had brights on.

This issue is not something I would try to fix with airbags. My previous experience with airbags was a major disappointment. When the pressure was high enough to make a substantial difference (about 45 psi), the truck sway was horrible. Even trying to run about 20 psi, the sway was bad and I had to set the Rancho shocks on high. They gave a very uncomfortable ride. I solved the problem by adding SuperSprings. With my current truck I have installed Timbrens but have yet to load the camper to see if this helped.

Either way, no more airbags for me.

DWeikert

York, PA

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Posted: 04/19/19 08:28am Link  |  Quote  |  Print  |  Notify Moderator

S Davis wrote:


One thing you don't want to do is unload your springs with the air bags no matter what height the trucks rear is, I always load up and then set the bags so the overloads just start to engage.


^^This^^

The perfect camper/truck combo would have the COG directly over, maybe just a little in front of, the rear axle. Making very little change on the weight on the front axle.

If you're inflating the air bags attempting to bring the rear of the truck back to its unloaded height, you're likely to have way too much air in the bags and probably a good amount of sway/rocking as you drive down the road. The friction between the individual leaves in a spring pack serves to reduce the rebound and thus sway. Air bags don't do that.

My method is to inflate the bags until the suspension begins to lift off the overload springs, then let a little air out so the overloads are just engaged. Obviously that's going to be lower than the unloaded height.


Dan
2008 Chevy D/A 2500HD ECSB
2010 Northstar 8.5 Adventurer


Grit dog

Black Diamond, WA

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Posted: 04/19/19 01:48pm Link  |  Quote  |  Print  |  Notify Moderator

An attempt at a public service announcement ended up in some pretty backasswards claims and recommendations here...

1 correct observation was that if you air back up a TC load to unloaded ride height, you're not taking advantage of any of the truck's rear suspension and you create a big white heavy bouncy ball.

On the other hand, "some" TC's "may" put a significant amount of weight on the front axle, but it is very few.

Second, having the back at OE height and the front sagging an inch? Couldn't be much more than that if you tried unless something different than every setup you see on the road... Did not affect caster appreciably and the little caster change did not wear the front tires. (Camber with an IFS front "could" do that if you really loaded it down.)

We're now disputing bad forum recommendations with bad forum recommendations.


03 Arctic Fox 860
07 Dodge 2500 deezul
"Obviously I don't want to overload my truck and be unsafe, but the reality is the truck is way more capable than the 10K GVWR they put on the sticker.
KJ"

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