Help with hitch / tongue weight

Ron Gratz wrote:

IDoMyOwnStunts wrote:
The TV rear axle is the fulcrum (pivot point). The entire truck is the lever. The WD system is the upward force applied to that lever behind the rear axle. The weight of cargo behind the rear axle AND the weight of the tongue of the trailer both apply downward forces behind the rear axle. Thus the WD system must apply enough upward force to counter both the weight of the trailer tongue AND the weight of the cargo behind the axle in order to restore weight to the front wheels.

Thanks for joining this discussion.

I agree with your statements. However, there is no consensus on how much load needs to be restored to the front axle. And, there is no agreement on whether it is necessary to restore any of the load which is removed due to TV cargo weight.

For example, Progress Mfg was the first WDH manufacturer to adopt the Front Axle Load Restoration (FALR) approach for adjustment of the Equal-I-zer WDH.
The Equal-I-zer Instructions state:

Step 1 - Set up Location:
Before installing the hitch, the tow vehicle and trailer should be loaded just as they will be while traveling. This includes full propane and fresh water tanks, and any other cargo the tow vehicle (passengers & gear) or trailer will carry, including ATVs for toy haulers. Tow vehicle “auto-level” systems should also be disabled or turned off temporarily. Park the trailer and tow vehicle on level ground and in line with each other. Chock and uncouple the trailer. Pull tow vehicle ahead about 5 feet to allow working area and set the parking brake.
Take the initial setup measurements for the tow vehicle by measuring from the ground to the top of the wheel wells directly above both the front and back axles of the tow vehicle. See figure 18. Record these on line A of the Weight Distribution Adjustments tables in Step 6.

Subsequent instructions state that, when the TT is hitched, the WD should be adjusted to eliminate 50-100% of the front-end rise due to tongue weight only.

Recently-revised instructions for Reese WDHs state:

INITIAL HOOK UP NOTE: Car and trailer should be loaded and ready for travel before final leveling.
1. Pick reference points on front wheel well. Measure and record distance to pavement.
Front wheel well to pavement ___________________

For proper adjustment of the WFH, Reese goes on to state:

Re-measure front wheel well reference point. The front wheel well height should be equal to the original measurement.

For both Equal-I-zer and Reese, the current WDH adjustment specifications are based on the front end load/height changes due to tongue weight only. The WDH adjustment does not compensate for TV cargo weight.

Ron

Thanks. I do see what you are saying. If I have it right, then using those methods described above, you would not be compensating for cargo behind the rear axle because you are preloading the vehicle as you would when camping, then taking the measurements. I just checked and my Ford manual says pretty much the same thing:

When hooking-up a trailer using a weight-distributing hitch, always use
the following procedure:
1. Park the loaded vehicle, without the trailer, on a level surface.
2. Measure the height to the top of your vehicle’s front wheel opening
on the fender. This is H1.
3. Securely attach the loaded trailer to your vehicle without the
weight-distributing bars connected.
4. Measure the height to the top of your vehicle’s front wheel opening
on the fender a second time. This is H2.
5. Install and adjust the tension in the weight-distributing bars so that
the height of your vehicle’s front wheel opening on the fender is
approximately halfway between H1 and H2.
6. Check that the trailer is level or slightly nose down toward your
vehicle. If not, adjust the ball height accordingly and repeat
Steps 2–6.

So, if I follow the manufacturer's recommendation to the letter, I will not be compensating for cargo behind the rear axle since it says "loaded vehicle". Interesting.