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-   -   Check My Numbers Please (https://www.irv2.com/forums/f45/check-my-numbers-please-372151.html)

xrated 12-26-2017 12:36 PM

The flaw in your numbers is that the amount of tongue weight present, does not change with a W.D. hitch installed. If you have 863 lbs of tongue weight, a W.D. hitch does not magically make part of that weight disappear. It's still going to be overloaded no matter how you slice it.

GoLeafsGo 12-26-2017 01:02 PM

Based on other interpretations I would beg to differ, it “distributes” the weight to 3 axles (TV front, TV rear, and TT). What percentage goes where depends on the load and length of the bars.

But even if you are correct, I don’t plan on towing with 78 gallons of fresh water anyway.

xrated 12-26-2017 01:23 PM

Interpretations don't matter, physics do. A W.D. Hitch doesn't make tongue weight disappear, it's still present at the ball/hitch assembly. You probably need to continue with your research. And actually, the distribution amount (percentage forward and percentage to the rear) is determined by the distance between the axles of the TV and the trailer.

And another thing to seriously consider, Toyota's 11% tongue weight "suggestion" or whatever it was is almost certainly not enough tongue weight to keep the trailer from swaying. A more realistic number is the 13 % number. Plus, a good W.D. hitch is going to weigh in at approx. another 75-90 lbs.....which obviously adds even more weight to your ever increasing tongue weight issue.

GoLeafsGo 12-26-2017 01:27 PM

And it’s not magic, it’s physics - opposing forces.

Tongue weight goes on mostly the rear axle, in my example 863 lbs., causing the rear of the vehicle to sag and the front to rise due to the downward force. I add a weight DISTRIBUTING hitch which creates an upward force dependent on the bars. This force counters the hitch force making the rear of the vehicle rise because the “weight” is being distributed to the other axles. I know that it goes towards the front axle because the front of the vehicle goes back down, and I know it also goes toward the trailer axles because the front of the trailer rises.

Whether it’s distributed 1/3, 1/3, and 1/3 is dependent on the hitch set up, which is why having someone who knows what they’re doing set it up is important.

I have seen convoluted calculations showing that typically it goes 18% TV front axle, 49% TV rear axle, and 33% TT axles, but again, those percentages can be adjusted depending on what the setup calls for.

xrated 12-26-2017 01:41 PM

The weight distributing aspect does not change the 10-13% tongue weight ratio. It merely helps the tow vehicle carry that load by distributing it more evenly. Tongue weight is the amont of downward pressure at the trailer tongue and is independent of how that weight is supported by the tow vehicle.

GoLeafsGo 12-26-2017 01:56 PM

You’re saying 100% of the downward pressure is supported by the tow vehicle and 0% is distributed to the trailer axles?

dayle1 12-26-2017 01:59 PM

Quote:

Originally Posted by xrated (Post 3960600)
The weight distributing aspect does not change the 10-13% tongue weight ratio. It merely helps the tow vehicle carry that load by distributing it more evenly. Tongue weight is the amont of downward pressure at the trailer tongue and is independent of how that weight is supported by the tow vehicle.

But weight distribution not only helps the tow vehicle carry the load, but with better balance it will also help the tow vehicle control sway. So, the tongue weight 'window' should become larger.

GoLeafsGo 12-26-2017 02:06 PM

xrated- If thatís true, and I donít think it is, Iíll load to set the tongue weight at 11% per Toyota specs.

That will make wet tongue weight 730 lbs, assuming 78 gallons of fresh/5 gallons black/500 lbs cargo, and Iím still well within manufacturer specs with room to spare.

If it doesnít distribute weight it shouldnít be called a weight distributing hitch ;)

AA4TG 12-26-2017 02:13 PM

The best way I can explain the tongue weight is, take the unhooked trailer and scale the tongue for x lbs. That x pounds is a constant unless weight is added or removed, or the trailer axles are moved forward or aft. The wd hitch shifts the weight on the tv axles more or less forward. It does nothing to the weight balance of the trailer ergo, the tongue weight.

AA4TG 12-26-2017 02:22 PM

Continuing, ergo the young weight remains unchanged, just the weight on each tow vehicle axle changes.

GoLeafsGo 12-26-2017 02:24 PM

So taking all the cargo and moving it to the rear of the trailer will not affect tongue weight because the axles haven’t moved for or aft? Years of experience on a teeter totter tell me that’s not correct.

When applying WD on my previous trailer I could hear the springs on the trailer axles making noise as load was shifted to them.

AA4TG 12-26-2017 02:29 PM

Not what I said. I said that the tongue weight remains constant unless weight were added or removed, or the tt axles moved. I was trying to explain the lb hitch has no effect on the weight exerted on it, just the weight distribution on the tv axels.

xrated 12-26-2017 07:20 PM

Quote:

Originally Posted by GoLeafsGo (Post 3960621)
xrated- If that’s true, and I don’t think it is, I’ll load to set the tongue weight at 11% per Toyota specs.

That will make wet tongue weight 730 lbs, assuming 78 gallons of fresh/5 gallons black/500 lbs cargo, and I’m still well within manufacturer specs with room to spare.

If it doesn’t distribute weight it shouldn’t be called a weight distributing hitch ;)

And again, you may find that 11% is not enough to prevent trailer sway. Most folks find that 12-13% of the GVWR number works pretty good for the amount of tongue weight to prevent or minimize trailer sway. My toy hauler, the way I load it is right at 11.5% and and the Blue Ox Sway Pro helps keep it under control. Even when I only had 11% on the tongue, it had a tendency to sway except in totally calm wind conditions.

Here is a link for you to click on and read....
https://www.rv.net/forum/index.cfm/f...d/14265335.cfm

And at the end of the second paragraph....
Note - When the WD system is engaged the actual tongue weight does not change. Recommended tongue weight is from 10% to 15%.

Notice, the author didn't say that the weight is NOT redistributed, he said that the weight didn't change. If you start out with 1000 lbs of tongue weight without the W.D. hitch and then you engage it, you still have a 1000 lbs of tongue weight.

keymastr 12-26-2017 09:31 PM

Will it be doable even using the axle weight ratings to squeeze the last pound of capacity out you can? Maybe, but your problem will be getting the individual ratings to stay within the limits. Your rear axle rating will probably be the hardest to stay within leaving you two options. Less tongue weight which will induce sway, or adjust the hitch to transfer more weight. The problem with that is it drives real spooky and any side forces really move you around. You may find that it drives better with the rear axle overloaded than it does when the weight is more distributed.

The reason Toyota recommends a tongue weight of 9 to 11% is because they want to advertise a higher tow rating and the only way they can is to make sure the tongue weight is low enough to be carried by the cargo capacity. That is why commercials show trucks towing flatbed trailers and boats because those trailers stay stable with tongue weights as low as 6%.

Good luck with it. I hope you have better luck than I did. I know my trailer came in with a dry weight several hundred pounds heavier than the brochure. You may get tired of playing the load balancing game, not carrying water, leaving things at home, replacing worn parts.


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