Second Opinion, and a few questions

Ron Gratz wrote:

Aron wrote:
So, here's my situation: my tow vehicle has a payload of 1364 lb (per the yellow sticker). Wheelbase of 119", and estimating 60" between the ball and rear axle.

I don't have a trailer yet, but I'm currently considering one with a dry weight of 5160 lb (GVWR of 6500 lb). I don't have good measurements on the distance to the rear axle. The trailer is 28'3" long, with an approximate 24' box, so I'm assuming (based upon photos) that the axles are centered or slightly behind the midpoint of the box, which would give a distance from ball to axle midpoint of approximately 195".

I'm thinking of purchasing a Blue Ox Sway Pro 10,000 GTW, 1,000 TW hitch (shipped weight of 96 lb according to the website). It appears that the spring arms are 29" long.

So, assuming that I can properly tension the spring bars to provide a full 2000 lb of load, that should generate approximately 297 lb of load applied to the trailer axles, correct? If I'm remembering my statics correctly, that means that 297 lb of load from the tongue would not be applied to the payload of the tow vehicle, correct? So even if I load the trailer to full 6500 GVWR, and load the trailer tongue to 780 lb (12%), I should not exceed the payload of the tow vehicle, correct? (1364-96-780+297=785) My family currently weighs 585 lb, so that still leaves me with 200 lb of payload buffer in case I can't tension the WDH fully, or if the trailer axles are further back than I think. And assuming that they grow another 100 lb or so, I would still have a 100 lb buffer. And that looks like a worse-case scenario, because I also wouldn't be fully loading the trailer to capacity.

Does all of that check out? Or is there a flaw in one of my assumptions? Thanks!

With a TT which is 28' overall, I would recommend a tongue weight percentage of 13%.
For a TT weighing 6500# the corresponding TW, at TW% = 13%, would be 845#.

Based on your dimensions, a TW of 845# would cause a load of approximately 845*60/119 = 426# to be removed from the TV's front axle with no WD applied.
If you want to follow Ford's WDH-adjustment spec which calls for restoring approximately 50% of the load which is removed from the front axle, you would need to adjust your WDH to restore about 213# to the front axle.

Again, using your numbers, to restore 213# to your front axle would require the WDH to be adjusted to transfer about 213*119/(60+195) = 99# to the TT's axles.
The corresponding load applied by each WD bar would be about 99*195/29/2 = 333#.

If you used 1000# rated WD bars and adjusted them to transfer the previously calculated 297# to the TT's axles, the corresponding load transfer to the TV's front axle would be about 297*(60+195)/119 = 636#.
This is significantly more WDH load transfer to the front axle than is specified by Ford.

Ron

Dangit! And I thought that I might have this puzzle solved, too...

I think that I'm going to have to expand my calculations spreadsheet to work out all of these numbers as well.

This was very helpful, thanks!