Dialing in Weight Distribution Hitch

[Jcoulter]

I have recently purchased a previously owned ‘21 GD Transcend 260RB. My tow vehicle is a ‘22 Ram 1500 with a 5.7 hemi. The trailer came with a Fastway E2 WDH. I’ve done a lot of research and it seems as though only one area is addressed when setting up a hitch. That consists of measuring the distance from the ground to the front wheel well when the truck is packed for a trip and detached from the trailer. You then connect the trailer and take the measure a second time. The goal is to be within a half inch of the first measurement. Adjustment is made by adding or taking away washers. What isn’t addressed are 2 areas:
1) should I not be concerned about the sag that the trailer is putting on the back of the truck? How much sag is acceptable? Wouldn’t the goal be to have the back of the truck have no sag at all when the trailer is attached?
2). What about the trailer? Shouldn’t the goal be to have the trailer be level from front to back? Thanks

[DougW9876]

1 Rear sag of the truck will be well controlled when the front is at the proper height.

2 Absolutely.

I have been using WDH systems for almost 50 years and I have used the same procedure for setting them up the whole time and it works pretty well. There is a good video of how to set one up.

https://www.youtube.com/watch?v=ZHYTw9e5oIY&t=38s

He visually explains it better than I can type it.

[Riverbug]

I went through the installation process for our E2 after realizing the dealer didn't take into account the 6" lift kit on our truck. It was obvious from looking at it that it was not setup correctly. After following all the instructions and making proper adjustments, we went to FL for a few months. While there, I went to Smart Weigh for a full weighing and analysis. Turns out that we were pretty close. The front was 200# light with the WDH engaged. I was told that was pretty good compared to many they see that are 600# or more off. The measurement method is a good starting point and where most people stop. For accuracy, you can get it weighed. Ultimately, the WDH is for just that, distributing weight. Having it level should be a byproduct of correctly distributing that weight. Of course, if the rear is sagging your headlights are pointing upward which isn't great. But again - that's not the primary purpose of the WDH.

A final note about Smart Weigh...because each tire is weighed individually you also get side to side weights which helps to know and where possible adjust the distribution of your goods to even things out as much as you can. Pretty hard these days with slides that have appliances and sofa built into them, but still good to know.

[Harvestmoon]

We also have the Fastway E2 and had to tweak the setup slightly (by adding a washer) from how the dealer set it up for us. The Fastway manual doesn't come out and say it, but what they are getting at with the fender measurement, and getting back to half way between the loaded and unloaded measurements, is you want to distribute about half of the trailer tongue weight. The fender measurement is a convenient proxy, but if you really want to know you need to weigh it. In fact, you'll need to weigh 3 times: Once fully hitched with the spring bars in place, once hitched without the spring bars, and then weigh the TV without the trailer. Then you can figure out your trailer total weight and tongue weight, and you can see how the weight is shifting between the TV axles and the trailer axles with and without the spring bars.

Probably easiest to just give an example, so here is my last weigh:

Bars on: steer 3440, drive 3640, trailer 4960, total 12040
Bars off: steer 3220, drive 3980, trailer 4840, total 12040
TV only: steer 3560, drive 2960, total 6520

A few quick calcs:
Trailer total weight = total combined weight (12040) - TV weight (6520) = 5520
Trailer tongue weight = trailer total weight (5520) - trailer axle weight w/ bars off (4840) = 680
Distributed weight = drive axle w/ bars off (3980) - drive axle w/ bars on (3640) = 340

So this gives me about 12% tongue weight and 50% weight distribution, so that is about right. Even with a good WDH setup, the drive axle is still carrying tongue weight, so the rear springs are going to compress compared to riding empty. Most trucks are set up from the factory with the front riding a little lower than the rear when empty, so when loaded will bring you more or less to riding level. The trailer should ride level when fully hitched, and if not then adjust the ball up or down vertically as needed.