Upgrade 23' FC FB to 25' FC FBT - F150 Tow Vehicle

[Dick tracy]

Originally Posted by AlbertF

The water weighs about 300 lbs, but probably doesn’t add more than 75 lbs to the tongue weight.

You didn’t mention front GAWR; is it 3400?

From your numbers, I suspect you have very little tension on the weight distributing hitch, and virtually no weight transfer.

I’d start with tightening the spring bars to get the front axle to its GAWR. It might be hard to do with a Hensley, and your factory receiver and truck frame may flex and prevent full weight transfer, but it’s worth a try. I know with my setup I can easily overload the front axle - but that’s with a stiff unibody car and a reinforced receiver.

With more tension you will also get more weight transfer to the trailer axles. With 1700 lbs payload and only 400 lbs in the truck, you’ve got 1300 lbs left - and even with only 20% transfer back to the trailer axles, you’re good up to a 1500 lb tongue weight.

EXACTLY, a properly setup WD system will load the tv front axle almost back to normal weight. On my 27fbt with full fresh water my tv rear axle weight is 80lbs less than with an empty fresh water tank.

[hikingcamera]

Originally Posted by Dick tracy

EXACTLY, a properly setup WD system will load the tv front axle almost back to normal weight. On my 27fbt with full fresh water my tv rear axle weight is 80lbs less than with an empty fresh water tank.

Actually it depends. I thought that was the goal too, until someone helped me understand the WDH directions in the Ford tow guide. Ford pickups are intended to only return 50% of the load back to the front tires. When I adjusted the WDH according to the Ford specs, suddenly almost all (if not all) our porpoising was resolved, and the rig still rows just as solid. If not more so. It was a game changer.

[AlbertF]

Originally Posted by hikingcamera

Actually it depends. I thought that was the goal too, until someone helped me understand the WDH directions in the Ford tow guide. Ford pickups are intended to only return 50% of the load back to the front tires. When I adjusted the WDH according to the Ford specs, suddenly almost all (if not all) our porpoising was resolved, and the rig still rows just as solid. If not more so. It was a game changer.

Intuitively, that makes sense with a pickup, because they’re designed to carry a substantial load in the back. With a car/SUV, a more balanced weight transfer is needed. However, I don’t think you want to take weight off the steer tires of a truck. That seems to be a recipe for instability. Perhaps the intent is to only add half as much tongue weight to the front as to the rear.

In any case, each combination seems to have a sweet spot where harmony is achieved. Some experimentation is needed to figure this out, and in this case, determine where ride and handling are optimized without overloading either TV axle.

[hikingcamera]

Originally Posted by AlbertF

Intuitively, that makes sense with a pickup, because they’re designed to carry a substantial load in the back. With a car/SUV, a more balanced weight transfer is needed. However, I don’t think you want to take weight off the steer tires of a truck. That seems to be a recipe for instability. Perhaps the intent is to only add half as much tongue weight to the front as to the rear.

In any case, each combination seems to have a sweet spot where harmony is achieved. Some experimentation is needed to figure this out, and in this case, determine where ride and handling are optimized without overloading either TV axle.

You add half of the weight difference back. The instructions in the manual are to measure the height of the wheel well with the trailer attached before adding the WD bars and then after, and adjusting the weight distribution until it's halfway between those numbers. They call it the weight distribution correction factor, and for most of their pickups and the Expedition (built on the truck platform, I believe) they set that return at 50%.


As you mentioned, I'd been towing with a mid-size SUV and a Subaru Outback before that, and there the goal was 100% redistribution. Our dealer even set up our rig that way as well, but we were getting a ton of porpoising down the road (and we had to really crank the tongue jack up to load and unload the WD bars). But when we were directed to that page of the tow instructions, and got the courage to back off the WD, the difference was amazing. (I honestly wasn't 100% sure I knew the difference between porpoising and crappy roads before that.)

[DCPAS]

Originally Posted by AlbertF

With a car/SUV, a more balanced weight transfer is needed. However, I don’t think you want to take weight off the steer tires of a truck. That seems to be a recipe for instability. Perhaps the intent is to only add half as much tongue weight to the front as to the rear.

You would think, except Ford also recommends 50% for its full size SUV, the Expedition. In pickups, Chevy and Ford use 50%. Ram 66% and Toyota 100%. Most hitch manufacturers say at least 50% and not more than 100%. It is a confusing issue, for sure.

[hikingcamera]

Originally Posted by DCPAS

You would think, except Ford also recommends 50% for its full size SUV, the Expedition. In pickups, Chevy and Ford use 50%. Ram 66% and Toyota 100%. Most hitch manufacturers say at least 50% and not more than 100%. It is a confusing issue, for sure.

Back when I was towing a much smaller trailer with our Toyota Highlander, we experienced pretty extreme rear sag, leading us to get the Blue Ox SwayPro in the first place. Other owners of the same trailer complained about the sag in their 4Runners, Sequoias, Tacomas, and even Tundras said it was the same for them. It makes a lot more sense now understanding these differences in how manufacturers design their vehicles around WDHs.

Of interesting note, one model of the 2021 Ford pickups actually recommends a 25% return (as seen in the screenshot from post #64).

[DCPAS]

Originally Posted by hikingcamera

Back when I was towing a much smaller trailer with our Toyota Highlander, we experienced pretty extreme rear sag, leading us to get the Blue Ox SwayPro in the first place. Other owners of the same trailer complained about the sag in their 4Runners, Sequoias, Tacomas, and even Tundras said it was the same for them. It makes a lot more sense now understanding these differences in how manufacturers design their vehicles around WDHs.

Of interesting note, one model of the 2021 Ford pickups actually recommends a 25% return (as seen in the screenshot from post #64).

For 2018 (the year of our SUV), Ford recommended 25% for all F-150's other than the Raptor, which was 50%. The F-450 which is 25% above was 50% then. Lack of consistency on top of confusion.