8100hd

acdii

Think of a LONG prybar stuck in the receiver. You grab the end of the bar and lift. You are now doing what the spring bar does, however, the weight you are lifting does not change, it is just being levered up. When you lever it up, the weight resting on the rear axle now moves forward, and back as you are now supporting some of that weight. The weight remains the same at the point where the pry bar enters the receiver, but the distribution of that weight is transferred by your lifting of the bar. With the WDH, you and the pry bar are replaced with the spring bars and the trailer frame. When the bars are brought up and tensioned, it forces the weight on the rear axle fore and aft. The weight on the ball is still there, it's the distribution of that weight on the rear axle that is moved.

Spring bars are sized at 10% of the gross trailer weight, so an 800 pound spring bar will distribute an 8000 pound trailer, a 1000 pound bar a 10,000 pound trailer, and a 1500 pound bar a 15,000 pound trailer. If you notice, it is also directly proportional to the 10% tongue weight as well. Sizing the WDH based on GVWR of the trailer is easier though. If the GVWR of the trailer is 8400 pounds, you need a 1000 pound spring bar. If it is 10,100, you need the 1500 pound bar.

kehyler

So I was thinking about this and after looking at weight distributing hitches it might be the case that the tongue weight is mostly unchanged. The two attachment points of the spring bars are infront of the ball (where it pushes up on the truck's hitch) and aft of the ball (where it pushes down on the trailer frame). Perhaps these two additional forces cancel each other and the net force on the ball is roughly the same.

acdii

That's a way of looking at it. The weight remains the same on the ball, the pressure on the ball increases from the springs. The lever action is in front of the ball pressing it up into the trailer socket, while the chain end pulls down on the frame pressing the socket down on the ball.

In simplest terms, the WDH doesn't remove any weight, it just changes where the weight is being applied.

5.0GN tow

I am getting a kick out of watching all you guys talking in circles saying the same things. Easy way to put it. The trailer's tongue weight can not change, it's a fixed value unless you move physical mass into or out of the trailer. The WDH will change the amount of that fixed value applied to the Rear axle of the truck and to some extent the truck as a whole. When WDH is hooked up and adjusted right, less of the mass of the tongue weight is carried by the rear axle/whole truck, and more is shifted to the trailer axles and front axle of the truck. The weight did not change, only what axles are carrying parts of the same weight.

So if you refer to the change in rear axle load when towing as the trailer's tongue weight then that measurement point does change, however the physical mass of the trailer is unchanged. The only different thing is where the same mass is being carried.

acdii

But wait, didn't you just say the same thing after laughing about us saying the same thing?

8100hd

kehyler

I have to admit that this made me smirk a bit.

5.0GN tow

yeah but I summarized all of your explanations in one lol. Hopefully we all made the same argument clear enough in 10 different ways to make anyone either understand or confused as hell!

mass-hole

I dont know what you are including in your curb weight, but when they determine the maximum tow rating from J2807, they have to include a 150 lb passenger and driver as well as a 65 lb hitch weight for trailers >5000 lbs.

That means the GCWR - curb weight of an optionless truck would be ~365 lbs greater than the stated maximum trailer weight.