waynec1957 wrote:
myredracer wrote:
Interestingly, the percentage based on factory dry weights is 10%.
I’m glad someone else noticed this; I’ve seen published tongue weights from different manufacturers as low as 9%. The general consensus (though not everyone agrees) seems to be manufacturers design some TTs with these lighter TWs to make them “half-ton towable”.
Please note that "myredracer" full paragraph stated:
Our TT has a tongue percentage of 14.5% when all loaded for camping and that's with empty tanks and just one battery. Interestingly, the percentage based on factory dry weights is 10%. I could see us being over 15% if we had a full tank of fresh water and two batteries, but probably not by much. Is handling negatively affected when you start to creep up over 15%?
I'm guessing the manufacturer knew the tongue weight would increase beyond 10% when the trailer was loaded for camping -- even with only one battery. Simply adding 150# of propane and batteries to the tongue of a 5000# trailer could change the TW% from 10% to 12.5%. And that doesn't include any effects of cargo carried in the front pass-through storage which is common in many TTs.
I raised the question in another thread, if a lighter tongue weight is designed into the unit by the manufacturer, why does actually towing at that tongue weight make the unit unstable (or does it)? My neighbor at our seasonal site tows new, empty TTs out of the factories in northern Indiana—last year he pulled over 100k miles. He just hooks them up in the parking lot and goes regardless of the dry tongue weight. He doesn’t even own a WDH. So what is it about loading these campers (assuming they’re balanced) that makes it necessary to add (on certain units) 4-5% to the TW? My sense is part of it has something to do with putting enough weight (causing friction) on the WDH for it to function properly.
For some TV/TT combinations, it can be shown theoretically and experimentally that the combination can become dynamically unstable if the tongue weight percentage is below a certain value. Whether the instability will cause handling problems depends on driver experience (your neighbor tows 100k miles per year) and on TV characteristics (I doubt your neighbor is towing with a SUV or a light pickup).
That being said, I’ve been looking into the premium hitches (the ProPride 3P and Hensley Arrow). One of the big differences between how these work compared to conventional WDHs is the premium hitches handle sway and weight distribution separately. Conventional WDHs use friction to handle them simultaneously. So looking at one of these hitches gives an idea of what happens if sway is addressed properly but weight distribution isn’t.
I think you might be confusing tongue weight and tongue weight percentage. Most WDHs with integrated sway control can control sway quite well with a tongue weight of 500#. However, a 500# TW on a 5000# TT gives a TW% of only 10%.
With the 3P or Hensley Arrow, either one, it doesn’t matter how much or how little weight you have on the tongue the trailer can’t sway (I got this from both Sean at ProPride and Terry at Hensley Mfg.).---
Remember -- Sean and Terry are in the business of selling trailer hitches.
So what I take away from all this is each TT and hitch combination must have a “sweet spot” where everything is in balance. And when using a conventional WHD not only would that “hobby horse effect” be possible I would also think sway could be an issue if that sweet spot isn’t hit.
For a given trailer load distribution, there is a TW% at which the lateral force exerted by the coupler against the ball will be minimized. This "threshold" TW% tends to be in the range of 10-15% depending on trailer dimensions and load distribution.
If the TW% is less than the threshold value, the lateral force acts in a direction which tends to make the TV/TT unstable in yaw (sway).
If the TW% is greater than the threshold value, the lateral force acts in the opposite direction and does not cause yaw instability.
So, it's important to ensure that the TW% does not go below the threshold, but it's okay to be over the threshold if the TV can handle the TW.
Ron