Towing with Auto Leveling

[RenkenHouseOnWh]

Hi all, I have a 2017 with the max tow package and it comes with auto level or airride. I also have a Curt weight distribution and sway control hitch. I pulled my 24ft hybrid camper last weekend 5100 LBS dry weight for the 1st time. Do I need to use the weight distribution part of the hitch since it has auto level? The ride did not seem as smooth as I was hoping. Do I need to set it up differently? I let the Tahoe level out before putting on the weight distribution part of the hitch. Any help is appreciated.

[Grit_dog]

No, I’m saying different systems are different.
But you just said the same thing I was tryin to get across.
You need to set the bars when the vehicle is at normal ride hight. Not let the trailer squash the suspension, then set the bars, then let it air up.
However that is accomplished has nothing to do with the type of system, fundamentally, but is purely geometric. (Presuming an automatic ride height sensing system that attempts to recover the same height regardless of other factors.)

[Terryallan]

Grit dog wrote:
Murphs, it’s not the same.
Checked owners manual for the ‘17 and it actually only talks about the old school way just like the 2021 manual but the 2021 calls for putting in service mode and adjusting the wdh then letting the bags pump up again.

This is NOT fundamentally the right way. Wdh works on load. Auto air leveling Suspension is exactly what it states. It works only on ride height with height sensors.

If you drop the air, let the trailer squish the rear suspension, do the measure the front height thing, when you’re done, the trailer WITH weight being pulled off the rear axle is still compressing the rear springs loading the ride height some amount.
When you air back up, the auto ride takes over, pumps up the rear suspension and by way of doing that, changes the geometry of the wdh connection. Effectively putting “more” load on the bars. Opposite reaction of adjusting the trailer jack height to make attaching the bars easier.
Except now you’ve changed the load the bars are seeing and how much weight it’s transferring.
Think about it from a purely geometric and statics standpoint.
You want the auto ride height where it is leveling the vehicle when you setup the weight dist. because it will always compensate for load and maintain the same geometry.

Those that don’t understand these systems and how wdhs affect the forces on the vehicle and how these 2 systems need to consider how each other works and how that is different than just a simple spring suspension.
The nuances may not be great with a lighter tongue weight, but the heavier the tongue weight, the more important this becomes.

I realize mine was a Ford. But after you unhooked, and let the TV level itself. Then shut off the air ride BEFORE it lowered the vehicle. It held the level position. Then you could adjust the hitch just as if it did not have air ride. Then when done. you just turned it back on.

But you say GM air rides don't work that way?

[Grit_dog]

Murphs, it’s not the same.
Checked owners manual for the ‘17 and it actually only talks about the old school way just like the 2021 manual but the 2021 calls for putting in service mode and adjusting the wdh then letting the bags pump up again.

This is NOT fundamentally the right way. Wdh works on load. Auto air leveling Suspension is exactly what it states. It works only on ride height with height sensors.

If you drop the air, let the trailer squish the rear suspension, do the measure the front height thing, when you’re done, the trailer WITH weight being pulled off the rear axle is still compressing the rear springs loading the ride height some amount.
When you air back up, the auto ride takes over, pumps up the rear suspension and by way of doing that, changes the geometry of the wdh connection. Effectively putting “more” load on the bars. Opposite reaction of adjusting the trailer jack height to make attaching the bars easier.
Except now you’ve changed the load the bars are seeing and how much weight it’s transferring.
Think about it from a purely geometric and statics standpoint.
You want the auto ride height where it is leveling the vehicle when you setup the weight dist. because it will always compensate for load and maintain the same geometry.

Those that don’t understand these systems and how wdhs affect the forces on the vehicle and how these 2 systems need to consider how each other works and how that is different than just a simple spring suspension.
The nuances may not be great with a lighter tongue weight, but the heavier the tongue weight, the more important this becomes.

[RenkenHouseOnWh]

Thanks everyone for the information. I think I will just need to play with it a little bit more using both the Weight distribution hitch and auto levelers since I am unable to turn them off.

[murphsfromaz]

dodge guy wrote:

Grit dog wrote:

Durb wrote:
If you can, disable the auto air bags and use the WDH to level your vehicle. If your auto level lifts the rear of the truck after your hitch has been set up it will serve to unload your front tires and possibly defeat the anti-sway capabilities of your hitch. Both scenarios make your tow worse and possibly unsafe.

Doesn't work that way. Can't just turn it off on a Tahoe.

It's not much different setting up an an auto level system with weight distribution, just cant use a tape measure. Either scale or trial and error until it "feels" right. The ride height will just remain the same.

It needs to be disabled somehow (pull fuse) until you get the hitch setup. Then you can reneable the system.

It can. Go into the system on screen. Then suspension, then click service mode. Be level first. Once you hook up the trailers electrical it will go back to normal. Disable your comfort setting for lowering when placed in park. This is how my 2021 Yukon XL Denali is set up.

[dodge_guy]

Grit dog wrote:

Durb wrote:
If you can, disable the auto air bags and use the WDH to level your vehicle. If your auto level lifts the rear of the truck after your hitch has been set up it will serve to unload your front tires and possibly defeat the anti-sway capabilities of your hitch. Both scenarios make your tow worse and possibly unsafe.

Doesn't work that way. Can't just turn it off on a Tahoe.

It's not much different setting up an an auto level system with weight distribution, just cant use a tape measure. Either scale or trial and error until it "feels" right. The ride height will just remain the same.

It needs to be disabled somehow (pull fuse) until you get the hitch setup. Then you can reneable the system.

[Grit_dog]

Durb wrote:
If you can, disable the auto air bags and use the WDH to level your vehicle. If your auto level lifts the rear of the truck after your hitch has been set up it will serve to unload your front tires and possibly defeat the anti-sway capabilities of your hitch. Both scenarios make your tow worse and possibly unsafe.

Doesn't work that way. Can't just turn it off on a Tahoe.

It's not much different setting up an an auto level system with weight distribution, just cant use a tape measure. Either scale or trial and error until it "feels" right. The ride height will just remain the same.

[Terryallan]

Refer to your owner's manual for the process of setting up your hitch with the auto level. I had one, and the instructions went as followed.

Take it to a level parking lot. Uh hook. Leave the vehicle running and let it level itself. Then before it can lower itself. Turn the auto leveling OFF. The vehicle should stay level, and not lower.
Then adjust the hitch as you normally would. I use the tape measure method. I get the front end back down to where it was unhooked. That will put any lost weight back on the front axle.
after you get the hitch setup with the leveling off. Turn it back on. It should not raise the rear high enough to change the weight transfer. If it does. the front will be high again.

That was my instructions, and it worked well.

[APT]

Agree with above, but here is some more detail.

Do you remember see-saws or teeter-tooters? Push/sit on one side, other side goes up with a fixed fulcrum in the middle. That is the same physics as dropping a trailer tongue on a tow vehicle ball. The fulcrum is the rear axle, and the "other side" is the front axle. A WDH restores weight removed from the front axle.
Here is a typical example:

1000 pounds of TW

Drop the tongue on the ball
TV rear axle increases by 1400 pounds.
TV front axle loses 400 pounds.

Air bags or auto leveling suspension does not change those weights. If someone were to adjust a WDH to restore all 400 pounds lost on the TV front axles, the rear axle would only have about 800 pounds more than unhitched with about 200 pounds going to the TT axles.

I like what HarleyEnough said about suspension height as "an artifact of the real purpose, a measurable artifact of what it's really doing".

[mkirsch]

Auto level only lifts and lowers the rear of the vehicle. It does next to nothing for weight transfer.

When you first lower the trailer tongue on to the ball, the front of your vehicle rises due to the "see-saw" effect: Trailer pushes down behind the rear axle, front of vehicle comes up, causing weight to come off the front tires.

The auto level only pushes up AT the axle, the pivot point of the see-saw. So the whole thing goes up, not just the rear.

Your WD hitch lifts up on the rear bumper, behind the axle, behind the pivot of the see-saw. This in turn causes the front end to come back down, placing weight back on the front tires.

Hopefully that explains why auto level is not a replacement for the WD hitch. They can work together, because they achieve different goals.

[dodge_guy]

The auto level needs to be disabled before you connect the WD hitch. Once you have it all setup then you turn it back on.

[rdhetrick]

As mentioned before, the purpose of the weight distribution is to put weight back on the steer axle. The only way you can effectively do this is to use a scale. Just looking at whether or not the truck is level is not a good indication. After you've got the weight shifted to the steer axle, you'll probably only have a very slight "out of level" on the truck.

[Durb]

If you can, disable the auto air bags and use the WDH to level your vehicle. If your auto level lifts the rear of the truck after your hitch has been set up it will serve to unload your front tires and possibly defeat the anti-sway capabilities of your hitch. Both scenarios make your tow worse and possibly unsafe.

[HarleyEnough]

Yes you still need the weight distribution. Although it may sound like your goal is to get the vehicle to sit more level, that's really just an artifact of the real purpose, a measurable artifact of what it's really doing. This is how we measure if the weight distribution is setup correctly. The real purpose of weight distribution is to transfer weight from the rear axle to the front axle. Why is this important? Because if you don't have enough weight on your front axle then you can't steer. That's a very scary situation. Keep in mind that this will be exaggerated even more when dragging all that weight up hill. It also may tow fine on dry roads because it has just enough weight on the front axle but you'll find out in wet or icy conditions, the tiny bit of weight you have left will not be enough to steer the gross combination weight of the truck and trailer.