Air bags and weight distribution--which comes first?

Ron Gratz wrote:

Campin LI wrote:
Another reason why some people feel they have too much truck rear end sag is that their WDH is undersized for the tongue weight of the trailer. --- If this is the case, you should actually get an appropriately sized WDH or alternatively use air bags to lift the back up a little (as long as you do not exceed the rear axle weight). In this example, the WDH bears some of the load and the airbags "sort of" bear some of the load.

IMO, an "undersized" WDH means that it cannot satisfy the front axle load restoration objective.

If the WDH cannot satisfy the load restoration objective, you cannot solve the problem by using air bags to lift the back up a little.
It makes no difference if the airbags bear some of the load -- they cannot transfer load to the front axle.

Ron

Agreed, a properly sized WDH is the best way, but as long as you are not exceeding rear axle load and you want a level truck, you can do it. My opinion is that a vehicle designed to drive level will be more stable if it is level.

Campin LI wrote:
Another reason why some people feel they have too much truck rear end sag is that their WDH is undersized for the tongue weight of the trailer. --- If this is the case, you should actually get an appropriately sized WDH or alternatively use air bags to lift the back up a little (as long as you do not exceed the rear axle weight). In this example, the WDH bears some of the load and the airbags "sort of" bear some of the load.

IMO, an "undersized" WDH means that it cannot satisfy the front axle load restoration objective.

If the WDH cannot satisfy the load restoration objective, you cannot solve the problem by using air bags to lift the back up a little.
It makes no difference if the airbags bear some of the load -- they cannot transfer load to the front axle.

Ron

BarneyS wrote:

Campin LI wrote:
WDH's rely on the trucks rear end sag to work. If the truck is leveled first by airbags, adding a WDH will do nothing because you have no rear end sag to lever up. Snip...

Not quite. The WDH will work no matter if there is rear end sag or not. Sag is not necessarily an indication that a WD hitch is needed. You could replace the springs on the rear of a truck with solid steel bars and prevent any sag at all but there would still be weight removed from the front axle and possible overloading of the receiver and rear axle by the addition of a heavy tongue weight. The WD hitch will help correct that situation.

I agree with most of the rest of your post except that I feel the use of air bags is normally not necessary at all when a WD hitch is properly sized and used. Thank you for your contribution to the discussion. :)
Barney

Agreed. It's a simple system with complicated mechanics. In trying to simplify a response, I ended up explaining it inaccurately. Thanks for pointing it out.

Another reason why some people feel they have too much truck rear end sag is that their WDH is undersized for the tongue weight of the trailer. They tilt the hitch head down all the way and hook up the chains and tighten them, etc but the back is still down (and usually the front is still up) and their bars look like the letter "U". If this is the case, you should actually get an appropriately sized WDH or alternatively use air bags to lift the back up a little (as long as you do not exceed the rear axle weight). In this example, the WDH bears some of the load and the airbags "sort of" bear some of the load.

Campin LI wrote:
WDH's rely on the trucks rear end sag to work. If the truck is leveled first by airbags, adding a WDH will do nothing because you have no rear end sag to lever up. Snip...

Not quite. The WDH will work no matter if there is rear end sag or not. Sag is not necessarily an indication that a WD hitch is needed. You could replace the springs on the rear of a truck with solid steel bars and prevent any sag at all but there would still be weight removed from the front axle and possible overloading of the receiver and rear axle by the addition of a heavy tongue weight. The WD hitch will help correct that situation.

I agree with most of the rest of your post except that I feel the use of air bags is normally not necessary at all when a WD hitch is properly sized and used. Thank you for your contribution to the discussion. :)
Barney

WDH's rely on the trucks rear end sag to work. If the truck is leveled first by airbags, adding a WDH will do nothing because you have no rear end sag to lever up. Using airbags only does not transfer weight forward so the weight is all carried by the rear axle (the amount lost from the front axle plus the trailer tongue weight). Therefore, you may exceed your rear axle capacity if you do not use a WDH. If your rear axle is not overloaded, you may not need a WDH at all. Therefore, my opinion is that if you have a heavy tongue weight, adjust the WDH with no air in the airbags and then add just enough air to start lifting the back of the truck but don't lift it. The airbags will stabilize the rear of the truck and you will get a better ride. Keep in mind that if you start lifting the rear of the truck to get it level, you will be increasing the load on the rear axle. If you are using a Reese dual cam or Equal-i-zer hitch, you will also be reducing the amount of friction available to the hitch which it needs by design to resist sway.

Ron Gratz wrote:

Damdifino wrote:
---My question is, what do I do when hitching up? Air up the bags first, then weight distribution? Vice-versa? How do I go about integrating the air bags with the weight distribution hardware?

AlbertaNewbie got it right -- air up first, then add tongue weight, then add wdh.

I don't know why Equal-I-zer would say to attach trailer and wd to tv first, then air up. There's nothing to that effect stated in their online set up instructions.

When you adjust the WDH first, and then add air, the bags will lift the rear of the TV.
When the bags lift the rear of the TV, the load on the WD bars will decrease.
When the load on the WD bars decreases, the load on the TV's front axle will decrease and the load on the rear axle will increase.
When the load on the front decreases and the load on the rear increases, the WDH will no longer be properly adjusted.
When the WDH is no longer properly adjusted, you get angry.
When you get angry --- (sorry, I just watched a DirecTV commercial)

Ron

^----This.

Ron Gratz wrote:

kevden wrote:
I am taking "auto-level system" to include rear air suspension. But, this is in the initial setup instructions section.

An auto-level system will not affect the WDH the same as a manually-adjusted air bag will.
Some TV manufacturer's state that the auto-level system should not be turned off.
Chevrolet states:

If a weight?distributing hitch is being used, it is recommended to allow the shocks to inflate, thereby leveling the vehicle prior to adjusting the hitch.

Others have similar instructions.

Our previous tv was a chevy avalanche with air bags inside of the rear coil springs. I always connected trailer and wd bars first, then added air. The air bags fixed the porpoising/rocking and made the truck a lot more stable. I did not air them up so much that it raised the truck any. IIRC about 20# is what worked good for my setup.

The OP stated, "---but it does squat significantly when hitched up. So I'm installing airbags."
If he's looking for the bags to compensate for a significant amount of squat, he needs to add air first (probably will need to "experiment" to get the right amount of air pressure) and then adjust the WDH.

Ron

Ok, that makes sense.

kevden wrote:
I am taking "auto-level system" to include rear air suspension. But, this is in the initial setup instructions section.

An auto-level system will not affect the WDH the same as a manually-adjusted air bag will.
Some TV manufacturer's state that the auto-level system should not be turned off.
Chevrolet states:

If a weight?distributing hitch is being used, it is recommended to allow the shocks to inflate, thereby leveling the vehicle prior to adjusting the hitch.

Others have similar instructions.

Our previous tv was a chevy avalanche with air bags inside of the rear coil springs. I always connected trailer and wd bars first, then added air. The air bags fixed the porpoising/rocking and made the truck a lot more stable. I did not air them up so much that it raised the truck any. IIRC about 20# is what worked good for my setup.

The OP stated, "---but it does squat significantly when hitched up. So I'm installing airbags."
If he's looking for the bags to compensate for a significant amount of squat, he needs to add air first (probably will need to "experiment" to get the right amount of air pressure) and then adjust the WDH.

Ron

Ron Gratz wrote:

I don't know why Equal-I-zer would say to attach trailer and wd to tv first, then air up. There's nothing to that effect stated in their online set up instructions.



Ron

From the owners manual:

Step 1 - Set up Location:
While installing or adjusting the hitch, the tow vehicle and trailer should
be loaded just as they will be while traveling. This includes full propane and
fresh water tanks, and any other cargo the tow vehicle (passengers & gear)
or trailer will carry, including ATVs for toy haulers. Tow vehicle “auto-level”
systems should also be disabled or turned off temporarily.

I am taking "auto-level system" to include rear air suspension. But, this is in the initial setup instructions section.

Airing up first could require more cranking on the tongue jack in order to get the tongue high enough to get the ball under it. (More work if you don't have an electric jack).

I have heard the argument that a proper tv should not need air bags or timbrens or any other suspension upgrade several times on this forum. That is like saying a good driver should not need accessories such as gps, or air conditioning, or specialty tires. While this is true that it should not "need" air bags or timbrens, they are an enhancement or addition that greatly improves the ride and handling of the tv. They make it safer and more enjoyable to drive.

Our previous tv was a chevy avalanche with air bags inside of the rear coil springs. I always connected trailer and wd bars first, then added air. The air bags fixed the porpoising/rocking and made the truck a lot more stable. I did not air them up so much that it raised the truck any. IIRC about 20# is what worked good for my setup.
The Timbrens in our current tv work great too.