Yes, the extension, by itself de-rates the tongue weight. The question is, is the derating the same amount with the weight distributing hitch (WDH)? I think not, becuase of the very nature of a weight distributing hitch.


The analysis gets complicated. Imagine where the stock receiver bolts to the frame. When they spec the receiver for 1100lbs with a WDH, what does that mean? It means that there is to be no more than 1100LBS at the point where the hitch is bolted to the frame. Now look at the tongue weight with-out a WDH, it is lower because the attach point has a mechinal advantage of a lever...the distance from the attach point to the frame. In my case the distance is such that a 500lb tongue weight equals 1100lbs at the frame without a WDH. Another intersting angle to this, Instead of bolting the receiver to the frame, hinge it. Okay, so it flops to the ground. The only way to make it work is with a WDH. So now here is my conclusion: Make the extension arbitrarily long, provided you could get a WDH to level out the extension, and you don't exceed the 1100lbs at the frame, you would be okay. However, with the "spring bar" design of WDHs that obiviously has its limits. Anyway, by adding the bumper as another attach point I think I have compensated for the inefficiencies of the WDH. (those inefficiencies allow the mechaincal advantage of the lever to derate the tongue weight)

However, after driving around I checked a bunch a measurments that I made, and they were the same. That tells me that I never reached the yield point of any of the compents, that is nothing is bent. So I may have some flexing...but I'm never reaching the yield point. If I do notice a change in any of my measurements, then I'll be bummed, and probably scrap the thing. I doubt that will ever see a change.

Funny, no one asked me about my welds.....

-Glen

 

I din't ask about your welds because your set seemed logical and the pictures of your assembly looks sound. (You look and sound like you know what you are doing) I assume you TIG welded everything, but you know what you can weld better than anyone.

 

Oh hi,

I used MIG, which is perfect for this application. I wish I could spell as good as I can weld...when I re-read my posts I wonder if anyone can actually understand them

-Glen

 

I know what you mean. I wish they had spell check on the threads so I can check what I'm about to say before I say it.

Your set up looks good to me. I'll check on if I can apply the same idea for my truck / trailer set up. Though I may have to use some heavier rated tubing since the tounge weight and trailer is more than yours.


GOOD JOB!

 

It looks like a good strong setup to me. My only question is this. You obviously used 2" square tubing, and bolting through the front, torquing to 150 lb/ft, did you in any way reinforce the bolt hole? As in weld a section of pipe inside it to prevent the square tubing from getting squished?

Because if you're worried about flexing and fatigue, over time the bolt hole will become elongated, and the tubing flattened out.

But otherwise, I like it. Good work.

 

Oh Hi,

Well I have to disagree with you on the Bolt hole elongation. The theory of using a bolt is to provide clamping action and it is the friction between the surfaces that prevents movement....by providing proper torque and the correct amount of surface area, then there is no shear forces on the bolt...hence there will be no elongation of the bolt hole.

Bolts are not suppossed to be used directly for shear forces, they are to be used to provide friction between the two surfaces that have a shear force. The only force on a bolt should be on its longnitudial axis...it actual stretches as you tighten it. Well that's the theory...it always scares me to death when I see a bolt being used as a hitch pin.....

I've seen the hole elongation in the 2" draw bars used with hitch pin ...but that would be expected...no clamping action.

-Glen