Forum Discussion

cruz-in's avatar
cruz-in
Explorer
Oct 13, 2019

Fun at the CAT Scales - Kind a Surprised at the result.

Hi Team,

I went to the CAT scales yesterday. All loaded up for camping, the numbers were all within spec (truck and TT). Then, with the CAT Scale app, re-weighs are only $2.50, so I figured I would fool around with WD adjustments. Here is what i found:

First, we tow our TT with a Hensley Hitch. The hitch has a 6 inch drop stinger. Truck is a crew cab, 6.5 foot bed with four corner auto leveling air ride. Trailer is 30 feet long.

Here are my measurements from the hitch ball on the Hensley:
Distance from hitch ball to center of front wheel: 18 Feet
Distance from Hitch ball to between the two trailer wheels 18.5 feet

With No Weight Distribution applied I rolled across the scales:
Steer Axle: 3300
Trailer Axle Load: 7200

With first increment of Weight Distribution applied:
Steer Axle: 3400 (+100 Pounds)
Trailer Axle: 7220 (+ 20 Pounds)

with second increment of Weight distribution applied:
Steer Axle: 3520 (+220 Pounds)
Trailer Axle: 7240 (+40 pounds)

So considering these two data points.

Of the load removed from the Drive Axle:
17% is going to the Trailer Axle
83% to the Steer Axle.

Given my math, and the relative symmetry of my setup, I would have expected a higher percentage transferred to the Trailer Axles.

I have a few other passes (with different settings) that support about 17% transfer to trailer axles. Keep in mind, this is not 17% of TW, It is 17% of what is transferred off the Drive axles.

As I said, all is good with the trucks specs. Just curious what I am missing.

Thoughts?

Is this typical of Pivot Point projection Hitches?

P.S. Setup drives great. tracks like it is on rails.
  • wnjj's avatar
    wnjj
    Explorer II
    Oct 16, 2019
    cruz-in wrote:
    Given my math, and the relative symmetry of my setup, I would have expected a higher percentage transferred to the Trailer Axles.


    When thinking about the weight transfer, it's helpful to consider your truck & trailer as one item with 3 axles (front, rear, trailer). Even with a tandem trailer, they effectively act as 1. Those 3 axles are the only places that support the weight and do so in proportion to the "shape" of your setup. Without WD, the shape is free to deform placing all of the hitch weight behind the truck rear axle, lifting some off the front in return.

    Once you introduce WD, it "bends" the shape up in the middle so the rear axle now sees less weight. The weight no longer seen by the rear axle will be shared by the two end axles (front and trailer). So while your setup may be symmetric when measuring from the hitch, it isn't when considering spacing of the axles. You also have to consider that some of the weigh removed from the rear with the WD was originally carried by the front so it returns there first before wanting to share onto the trailer axle.
  • BarneyS's avatar
    BarneyS
    Explorer III
    Oct 16, 2019
    If you find you cannot transfer enough weight to the front axle of the truck, even when the Hensley jacks are drawn up to their maximum recommended amount, then I would suspect that the WD bar socket bushings in the hitch head need to be replaced. That is a very simple task.

    First you remove the bars, The remove the small bolt on the bottom of the hitch head right between the two bar sockets that holds the bushings in the head. This will allow you to remove the bar bushings and inspect them. If the inside edges are worn thin where the bar pushes against it, then simply order new ones from Hensley. You will notice an immediate improvement in the amount of jack raising necessary to achieve the needed weight transfer.
    Barney
  • mkirsch's avatar
    mkirsch
    Nomad II
    Oct 16, 2019
    Agreed with Barney. It's a matter of physics. All WD hitches perform the same function in the "pitch axis." Where they differ is in the "yaw axis."

    You would get the same results from any WD hitch as far as weight transfer goes.

    But, you are still missing the weights of the EMPTY truck. Whichever one of the three settings gets the front axle weight as close to what it was empty, is the one to use.
  • BarneyS's avatar
    BarneyS
    Explorer III
    Oct 16, 2019
    A Hensley is no different from any other WD hitch when it comes to weight distribution.
    Barney
  • lbrjet's avatar
    lbrjet
    Explorer
    Oct 15, 2019
    15-25 percent transfer to the trailer axles is normal, so you are on the low end. Not sure if a Hensley is different.
  • BarneyS's avatar
    BarneyS
    Explorer III
    Oct 14, 2019
    You need to roll across those scales with just the truck before anyone can tell you if your WD is right or not. Need to find out the weight on both of the axles with no trailer attached. Then the numbers you have posted can be used.
    It might also help if you gave the make and model of the truck you are using as a tow vehicle.
    Barney
  • cruz-in's avatar
    cruz-in
    Explorer
    Oct 14, 2019
    Trailer is an 2004 30 foot Airstream. The older ones (like ours) much lighter than the current model. It weighs in, fully loaded, at about 8K pounds.

    Here is the info with Drive Axle added.

    My gut tells me, it is the auto leveling air suspension creating these numbers. I disable it to set the WD. Thanks in advance for any thoughts.

    With No Weight Distribution applied I rolled across the scales:
    Drive Axle: 3660
    Steer Axle: 3300
    Trailer Axle Load: 7200

    With first increment of Weight Distribution applied:
    Drive Axle: 3520
    Steer Axle: 3400 (+100 Pounds)
    Trailer Axle: 7220 (+ 20 Pounds)

    with second increment of Weight distribution applied:
    Drive Axle: 3380
    Steer Axle: 3520 (+220 Pounds)
    Trailer Axle: 7240 (+40 pounds)
  • librty02's avatar
    librty02
    Explorer
    Oct 14, 2019
    What were the drive axles weights at each weigh?
    What truck and trailer do you have?

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