Weight Distribution Hitches

Thanks for the detailed explanation, OG.  My reference to mostly getting the vehicle leveled out was a quick and dirty summary of the Fastway video that basically illustrates the steps you described.  I have no idea whether the video's steps apply to other WDH's since I've never adjusted any other kind but Fastway.  They also provide detailed written instructions, which are basically the same as the video.

+2  Thanks for taking the 'mystery' out of this important topic.  Although it was only experienced a couple times as we would tow our 177 up some rather steep inclines on loose gravel in the Rockies and felt the front tires slipping a bit (on both our '08 and '13 Explorers) it now makes sense.  Fortunately the fully loaded 177 was only 2900 lbs and tongue weight was just under 295 lbs.  After replacing one of our batteries a couple years ago with a Trojan T-1275 (85 lbs) the tongue weight shot up to 320 lbs with a fully loaded trailer.

Originally posted by lostagain Glad to see that someone else on this board is 75 besides me.   I've adjusted our Fastway E2 for two different trucks and trailers.  It was mostly just a matter of moving the hitch bracket or the torsion bar L brackets up or down, to achieve a level TV.  Fastway has a helpful video on how to do it.  Since all WDH's are used on different TV/trailer configurations, it'd seem that they'd all have to have some kind of adjustment capacity.  I never towed our 172 with our Ford and it may have not really needed a WHD for that weight of trailer.  It sure smoothes out the ride with our Sonoma, though.

It is a common misunderstanding that you are supposed to adjust your wdh to achieve a level tow vehicle.

That is not the case. Understanding why is important because it also explains why using a wdh can be so helpful in improving ride, handing, braking, and safety while towing, especially with smaller shorter TVs.

Consider what happens when you hitch up a trailer with say a 500 lb tongue weight. Where does the extra 500 lbs go? If you said the rear axle you'd be right but that's only the beginning.

Think of the TV as a kids teeter totter with the pivot at the rear axle and a kid sitting on the front axle, and nobody on the other end of the teeter. The kid is holding himself up, all his weight is on his feet. That's a tow vehicle with no trailer.

Now, put another kid on the other end of the teeter. That's the equivalent of dropping the trailer hitch onto the ball. What happens? The first kid suddenly has less weight on his feet. If they're well balanced neither kid has to hold himself up. But it's not like the kids are suddenly weightless, their weight has to go somewhere. That somewhere is the pivot point of course, which suddenly went from having no weight on it to having the weight of two kids.

Same thing happens to the rear axle of the TV. It always ends up with more weight on it than the actual tongue weight. How much more depends on 3 things. The tongue weight. The tow vehicle wheelbase and the distance from the rear axle to the ball. Just like when you balance a fat kid with a skinny kid on a teeter by putting the skinny kid farther out or the fat kid farther in, having a long wheelbase tow vehicle results in less lightening of the front axle than if you have a short wheelbase TV. That's why smaller shorter wheelbase vehicles are not as good at towing as longer ones, and the worst ones for towing have a short wheelbase and a long rear overhang. In fact if you had a vehicle where the rear overhang was the same as the wheelbase and you put a 500 lb tongue weight on it, the weight on the rear axle would be 1000lb and the front axle weight would go down by 500lbs.

Ok, so now back how a wdh helps and how to set it up. Your tow vehicle, whether it's a pickup or an SUV, is designed to carry load primarily in the rear. It's rear axle is built heavier for that reason. But of course you don't want more weight back there than necessary. Your front axle is expected to have a certain amount of weight on it in order for it to steer and brake the vehicle properly. So if you can you want the front axle to be carrying it's normal weight just like it would without the trailer.

The wdh achieves both these objectives by applying a torque (technically it should be called a moment because nothing is actually moving) at the ball, which tries to rotate the trailer back on it's axle while pushing the tow vehicle down on its front axle). These two moments balance each other, so nothing moves. If they didn't the whole rig would want to flip over on its back.

Your wdh is set up correctly when the weight on the front axle is the same as it was before you hung the trailer on the ball. That means that the tongue weight and no more than the tongue weight has been added to the rear axle, which achieves that objective of keeping the rear axle load low.

But the rear of your tow vehicle will have the additional 500lbs on it so it will be sitting lower than it was before, and the vehicle will not be level. That's ok, it's what the engineers who designed the TV intended.

If you tensioned the wdh further trying to get the TV level, you would be stressing both the trailer and the TV more than necessary, and also putting more weight on the front axle than was intended by it's designers.

So how do you know when you have the right wdh tension to load the front axle correctly? By using suspension height to gauge load weight.

Park your rig in a flat parking lot. Put a piece of painters tape on each front fender directly above the axle. Measure the height to the tapes from the ground with the trailer hitch off the ball. Then drop the trailer onto the ball and tension up the wdh until the height of the tapes drops back down to what it was, but no farther.

Hope all that is clear...

Skip, FWIW When we purchased our Rpod new, the RV dealer told us the exact same thing they told you. No WDH needed, just go with a friction bar. After a couple of short trips, I ordered a WDH from Etrailer.