WDH and airbag setup Question

cruz-in wrote:
So here is my setup:

2010 F250 Diesel 2WD CC Tow vehicle
11.5K trailer fully loaded
1200 to 1250 Pound Tongue weigh once loaded
Hensley Arrow hitch
1400 pound Springbars
Truck equiped with airbags

Been reading lots (and practcing) and pertty much got the setup up down but not sure about airing up the airbags. so far I have been:

1) Setting weight distribution so front bumper is about where it is whe not towing.

2) Then adjusting the airbags to level up the whole rig. Been taking 25 to 35 pounds of air in the bags.

Seems to drve real well except when I hit a bump there is a bit of porpoising. Nothing to dramatic, just a little bit annoying.

Is therre something I can do in my setup to limit the porpoising?

Thanks
Dan

You are going about your adjustments backwards. By doing the method described above, you are transferring too much weight back to the front wheels.

With aftermarket airbags, here is your adjustment procedure:

1. Measure truck fender heights on all four corners unhooked.
2. Hook up. Do not engage spring bars.
3. Air bags up to desired ride height in rear, ignoring front. My suggestion is to air them until your rear ride height is a bit lower than unloaded ride height.
4. Now, engage spring bars and adjust until front ride height is where you want it. Ford's towing specs in recent years have been to have front ride height at 1/2 the distance between unhooked ride height and hooked ride height (no spring bars). For Example: Unhooked fender height of 37". Hooked no bars ride height of 39". Target ride heigh with spring bars engaged is 38".

Keep in mind that as you engage the spring bars, the rear of the truck will rise. That is why you don't air the bags up to level the rear of the the truck to unloaded height. If the rear of the truck is at normal ride height while hooked, and THEN you engage spring bars, your rear ride height is going to be higher than unloaded ride height. You don't want that.

In my case, I got the rear of the truck within 1/2" hooked up, no spring bars. I then, cranked on spring bars until I got the front where I wanted it. In my case, the front is 1/2" higher than unhooked. Rear is at unhooked ride height.

You will find that the front ride height may need a bit of tweaking. In my case, my front ride height is a bit lower than Ford recommends. My truck rides much better as is. It did take a few trips to get it the way I wanted it.

Hope this helps.

Assuming the hitch is setup correctly keeping the trailer level (or slightly nose down), I would look at your tounge weight. Light tounge weight will cause porpoising. At 11500 lbs I think 1250 lbs is on the light side. Try shifting gear to get maybe 1400 lbs on the tounge. The range is generally considered to be 10-15% of the total trailer weight should be on the tounge. I personally shoot for 12-13%.