Understanding trailer weight and sway

[jproctor9]

I've seen a number of weight and sway videos but found this one very interesting - especially the point on too much tongue weight and pulling up/down hill. The examples using models and a treadmill demonstrate what can happen...and happen quickly.

It's 12 minutes well spent IMO.


https://youtu.be/JeEEC5eVNCk

[charley patton]

can anyone help me understand what my blue ox trac-pro bars are doing to my rig? here's the deal:scale says tv weighs 5400(2260 steer; 3140 drive). i load the truck and trailer, gas up, wife and pets in, go across the scale(with the bars on) and i get 3000 steer; 3460 drive; 6320 trailer. that looks like 320 tongue weight, when i should have around 630. i'm not smart enuf to know whether i have a good set-up or not. is it good to have better balance between the steer and drive axles which i do, or have i taken too much tongue weight away? i have 3800 limit on rear axle capacity. the loaded rig looks real level to the eye. thanks in advance.

[PDXDale]

Your adding 3460-3140=320lbs to your rear rear axle, but also some to your front axle due to the bars being engaged. your difference on the front axle (740lbs) also contains the weight of wife, pets, gas etc, according to your note. So the truth is somwhere below that.
The best to figure everything out is doing measurements without trailer and then with weight distribution hitch engaged, but everything else the same. your TrakcPro, when dialed in correctly, will take off some weight from your rear axle, and shift it to the front axle as well as a bit to the trailer axles.

[charley patton]

the issue for me is how much being transferred to the steer axle is good? my rig, looking at it in profile, looks fantastic(level). if i have a loaded trailer at 6320 and you assume 630 for tongue weight, then only half of it is going to the drive axle. is that good? i had a guy on another forum this a.m. telling me i should park it immediately because of jackknife concerns. idk how he came up with that, but it scared me. the blue ox tech guy told me this a.m. that as long as i'm level all the way around and it drives good, i'm okay. they don't even want to talk about weigh scales. curious, huh?

[charley patton]

btw, i don't own the profile setup anymore. i've got a completely different rig and tv.

[PDXDale]

The actual weights, when taken in different load situations, can be misleading. Go by measuring distances from ground to wheel well on your truck's axles (and don't change the load in the truck in between). Without trailer, then with full tongue weight on ball (no bars engaged), and then with bars engaged.

In my opinion, a good rule of thumb is to try to get your front axle halfway back to unloaded measurment.

Let's say your distances are:
Truck only: 40, 40
Full tongue weight on ball: 42, 37

So by applying your bars, you should target a front measurement of 41 inch. That will give you a good general setup for most rigs. While doing that, you will see the rear axle going up a bit (compared to with full weight on ball), as your hitch is transferring some weight from there to the front.

From there, it's characteristics of specific truck/trailer combinations and personal preference. With my current rig, I like to bring my front axle all the way back to unloaded measurement, so transfering even more weight. Play around with a little bit more and less if you don't like the ride yet.

[charley patton]

do you have any idea why a guy, when presented with my weight data, would tell me i have an unsafe rig?

[PDXDale]

The +740lbs on the front axle seem a bit high, but impossible to say without knowing how much besides tongue weight you aded to the truck. Are your truck weights above correct? Your truck solo seems much heavier in the back then in the front.

Just for reference, my F150 with people in the cab (2 adults, 2 toddlers) and some stuff in the bed, but no trailer, has 3300 FA and 2600 RA. When hooking up our trailer and bars engaged, this changes to 3150 FA and 3600 RA. Those are the last weight measurements I took, adjusted to more weight transferred now as mentioned above and haven't weight it yet.

[charley patton]

my truck unloaded except for me and a full tank of gas is 2260 steer and 3140 drive, total 5400. my gawr rr is 3800, so i can put up to 660 on the rear axle. with the way the hitch is set up, now, i'm presenting 320 on the rear axle. if i get close to your set up, i obviously need to put more weight on the rear, but i'm not sure how to do that short of changing my rig's profile to a more unlevel state.

[huntindog]

can anyone help me understand what my blue ox trac-pro bars are doing to my rig? here's the deal:scale says tv weighs 5400(2260 steer; 3140 drive). i load the truck and trailer, gas up, wife and pets in, go across the scale(with the bars on) and i get 3000 steer; 3460 drive; 6320 trailer. that looks like 320 tongue weight, when i should have around 630. i'm not smart enuf to know whether i have a good set-up or not. is it good to have better balance between the steer and drive axles which i do, or have i taken too much tongue weight away? i have 3800 limit on rear axle capacity. the loaded rig looks real level to the eye. thanks in advance.

WD does not remove TW. Read here as to how it works. Especially the last two lines.
Hint: You are confusing TW with rear axle weight. They are not the same thing.
https://www.mygrandrv.com/forum/show...l=1#post436541