Distribution Hitch Preload

X2. If you are using it to bring the REAR of the truck back up to unloaded height, you are using it wrong, and probably explains why you have so much pressure on the bars that is making you so concerned.

You don't need a scale, just a tape measure, some low-tack masking tape (if you don't want residue on your paint) and a reasonably flat area such as a paved driveway or parking lot.

PAY NO ATTENTION TO THE REAR SAG OF THE TRUCK.

It looks like you have a new truck, a 2010 F250?

That truck probably has "jounce bumpers" on the front end (most modern 4x4 trucks do) that prevent the springs from compressing past unloaded height. SO you can't just go by the front end measurement anymore. Once you hit unloaded height, it's just going to stay there no matter how much additional pressure you add to the springs. The additional pressure can cause suspension damage if you crank enough in.

When adjusting your hitch, you need to sneak up on the unloaded height, and actually stop a little BEFORE you get there. This will leave your rear end sagging, probably. That is something you would mitigate with suspension aids such as airbags, but really the truck is meant to squat as much as 4" with a load before you need to start thinking about suspension aids.

A WDH isn't intended to return the rear of the truck to its unloaded height. If it's adjusted to bring the front of the truck back down to normal height or at least halfway back down, you should be good to go.

Im late responding. Still am wondering about all this.
Hitch is a Class V now. So, 2,400 lb on the tongue and 17,000 weight trailer limit.

As a start, try and answer some of these questions and I may be able to add more.

1. How do you know when you have achieved proper WD for your truck?
I compare the height unloaded, then with the trailer on. I look at either bumper height or the helper springs on truck or both.

2. What year, make and model truck is it?
98 Ram 2500

3. What is the loaded TW of your camper?
wish I knew…

4. How many pounds of cargo are in the truck bed aft of the rear axle when you are trying to adjust the WD hitch?
Lots, 800-1000

5. Are you pulling hard on the pipe or lever snapping up the WD brackets?
yes, if trailer not jacked then I have an extra bar to make a longer lever, this is safer for handling the bar, but , yes, lots more force. That the stock lever is so small is of concern that I am doing this. Note: 30,000-40,000 miles of towing on bad roads so far with this…

6. What is the rating of your WD bars and hitch head assembly?
bought used, no idea. receiver is a solid square, not a tube.

7. What year/model camper?
1997 hilo, 4200 lbs

If we know those items, then I can ask about some for dimensions of the camper and rear overhang on your truck and give an estimated load the WD bars will be providing.

Hope this helps

John

Seems a lot of vaguaries in the questions. John's your man to answer this as best as possible. I will add in my experience, I was dialing too much spring into my setup early on (before I had accurate weights) and my 1100 lbs of tongue with my 1200 lb bars actually put enough force on the receiver to tear out the steel on the bottom of the OEM receiver tube! I have had a Drawtite unit installed as a replacement over the Orignial for about 8 years now and it has been very good. No flex or wind up. So, for reference, I'd worry as much about the receiver as the bars. The bars can probably take it. The weaker link in the system, not so much. Last time I weighed mine years ago it was putting enough force on the front axle to return to nearly zero at the start, plus like 50 lbs. Get weights then youll know.

I'm not an expert, but if you are jacking the front of the truck/trailer up good bit, and it still takes a lot of force to lock the bars, then it sounds like you are putting to much force on the bars to me.

my goal when it is all set up:

1. trailer level

2. steer axle weight is approx the same as unladen to perhaps a little
light. In other words, about 80% to 100% FALR(verify at CAT scale)

3. rear of the truck will squat a small amount compared to unladen

To hitch up:

lower coupler onto ball.
Raise tongue and back of truck with tongue jack high enough to easily tension bars.
Retract jack. Go drive.

Again, the scales are the easiest way to confirm good setup. Raising the coupled trailer/truck in order to easily connect bars is best safety practice.

ajriding wrote:

To get the truck to sit at normal height takes a lot of spring tension....I understand the hitch, so don't need instruction on how it works, just not sure how much it can handle.

There are contradictions in the phases above. Every WDH is designed to handle the weight the manufacturer rated it for in terms of static tongue weight. Age, fatigue, manufacturing defects, will vary that. What do you mean by "get the truck to sit at normal height"?

You are not getting answeres to your questions because owners do not measure the force of the lever used to snap up the WD bars. Owners do not measure the forces on the bars themselves. I have never read of any account of WDH bars snapping, only bending or not providing enough front axle weight restoration.

Hi,

I will try to help but need more info about what your setup really is.

Seeing pictures of your setup, the WD hitch, truck and trailer in this case really helps and we will need some actual loads your trying to have the WD hitch work on. Will get to that in a moment. See some answers inserted after your questions

ajriding wrote:
I am wondering how much tension (preload) I can put on the weight distribution hitch "springs". Mine use chains attached to the spring or trunion bar and tension is applied by pulling up on the chains.

How much can the hitch typically take?
WD hitch spring bars have a rating for them as does the hitch head and the snap up chain brackets. By the mfr, they are rated to take the towing loads imposed by a loaded tongue weight plus any truck bed load weight up to the limit of the actual WD bar. Meaning if you have a 800# loaded TW and 400# of weight aft of the rear axle in the truck, the spring bars need to be rated at 1,200#. In this case, a 1,200# WD bar is rated to handle the conditions that are imposed on the hitch during normal towing.

I have along lever tool to set the chains in place and can put the tension on, but at what point do I risk breaking something (springs, hitch cradle etc)?
If you are trying to pull up on the pipe or lever to preload the spring bars by very much lift/pull, that is not good. That can be very dangerous and many trying it have gotten really hurt bad when the pipe slips off their hand or the snapup. Let us help you learn the method on how to do this by flipping the snap ups by hand. There is a method on how to do this that takes almost no effort to snap up extra heavy spring bars, like I have.

Once everything is hooked up, the risk of breaking something comes when you exceed the ratings of the WD bars. They are sized to the loads they are rated for. Yes there is some safety factor but the mfr would not normally warrant a new hitch used over it's rating as it will break if you go over by enough.


To get the truck to sit at normal height takes a lot of spring tension. I typically have the tongue jack raising everything when I do the WD bars, but still is a lot of force.
By your wording, "sit at normal height" their may be something not understood by us as to what you declare are proper WD settings for your truck. What is the criteria you are using to declare WD on the truck is correct?

I understand the hitch, so don't need instruction on how it works, just not sure how much it can handle.
Also, when I go through road dips the tension greatly increases, so needs to be considered?

Mine is similar to the Curt

The WD hitch manufactures know and design the load ratings to handle compound angle turns and up and down dips up to the rating on the WD bars and hitch components. When you go around a turn and the truck tires are on an angle to the TT tires, one WD is holding all the load, the other bar can be totally unloaded. They know this and design the ratings to handle it. Same goes for coming off a high up RR crossing then the hitch will back flex upon itself.

This all comes back to selecting the right hitch parts for the actual known weight of the camper loaded TW and the truck bed loads you are trying to use it with.

If you do not know the ratings of the WD hitch, the truck loads or the loaded camper TW, then yes, you might break the WD hitch or the camper A frame if the loads are high enough. The camper A frame has to be able to handle those loads too. I have seen several A frames bent due to WD hitches. They have a limit too.

As a start, try and answer some of these questions and I may be able to add more.

1. How do you know when you have achieved proper WD for your truck?

2. What year, make and model truck is it?

3. What is the loaded TW of your camper?

4. How many pounds of cargo are in the truck bed aft of the rear axle when you are trying to adjust the WD hitch?

5. Are you pulling hard on the pipe or lever snapping up the WD brackets?

6. What is the rating of your WD bars and hitch head assembly?

7. What year/model camper?

If we know those items, then I can ask about some for dimensions of the camper and rear overhang on your truck and give an estimated load the WD bars will be providing.

Hope this helps

John

ajriding wrote:
Here is it loaded using the next shorter chain link. Lots of tension on it, and has raised truck a little higher than without trailer.


Not sure if pic is viewable, but bars are loaded and bent.
The trailer frame is strong enough, and Class V hitch won't know its there. More concerned just about the receiver and WD components related.
Not worried about the ride, or the other details, just the safety of the system.
I could tow trailer without any WD help, but rather have weight of truck…

Thanks for other related comments, but Im just looking at how much tension goes into this and thinking, wow, thats a lot of stored energy…

If the back of the truck is higher with the trailer, than without the trailer, then you are putting too much force on the spring bars. It should be the same height as when unhitched, and most likely an inch or so lower.

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Barney