Sway problems

[Wscott52]

2015 F250 crew cab short bed 4x4 diesel -8650lbs (front 4900,back 3750)
35”x 12.50 x 18 (12 ply toyo)
2016 keystone impact toyhauler - 10,600lbs loaded, 1550 tongue weight

Curt WDH 17501 series with bars not chains

Level lot unhooked truck- front fender 42 1/2. Rear fender 43 1/2
Level lot hooked no wdh- front fender43 1/2. Rear fender 41 1/2
Level lot WDH front fender 42 1/2. Rear fender 42

Ball on unhooked truck is 26” to top of ball
Trailer top of hitch 24 1/2

Whew. I think i have given you all the details.
My problem is sway over 50 mph, i have read and researched all that i can. I have spent hours in a parking lot with no success. I am so frustrated right now i can scream. This is my 5th camper so I’m not new to this. I own and drive semi trucks so I’m not new to towing.
Comes a point where i need your expertise please.
Thank you in advance!!
Wscott

[carringb]

Good luck!

PS - might want to drop the steer tires to 45 psi, again based on the load table for those tires.

[Wscott52]

Ok trailer at 80 and drop truck to 55
Got it I’m doing that now and going for a drive
Wish me luck

[carringb]

Wscott52 wrote:

carringb wrote:
What tire pressure are you running on the truck. Since you're running a considerably wider tire than stock, you should be running a lower PSI in order to maintain uniform tread contact. Especially if those are M/T tires, because if you run max PSI, they'll be riding on the center tread blocks only, which have zero lateral stability.

They are AT 12 ply 80 lb but have them at 70?

Still very much too high. Your tires area rated at 3,630 lbs each at 70 psi.

Best thing is to weight your front and rear truck axles when loaded. For now, let's assume you have the WD adjusted per Ford's spec, where half the front-end-lift is restored when you have the bars hooked. This will put about 2,000 pounds on you rear axle, in addition to your 3,750 empty rear axle weight. This will put your loaded weight about 5,800 pounds. The Toyo load chart for your tires indicate they can carry 2,910 lbs each @ 50 psi. Running at ideal pressure give you the best road traction. Sometimes it works well to add another 5 psi for a high center of gravity, but that's not the case with a bumper pull trailer.

Here is the Toyo inflation chart. Your tires are at the top of page 7:
https://www.toyotires.com/media/2125/application_of_load_inflation_tables_20170203.pdf

That adjusted PSI will trip your TPMS light. Some dealer will adjust it, some won't. Most folks just spend the $20 for a lap-top interface, and make the change in ForScan. But for a new truck under warranty, I'd try to get the dealer to do it first.

As for the trailer, low psi will also make it unstable as the sidewall flexes. But I think think 50 psi is low enough on its own to cause all your issues. But it could very well be part of the problem, along with your over-inflated truck tires.

[Wscott52]

carringb wrote:
What tire pressure are you running on the truck. Since you're running a considerably wider tire than stock, you should be running a lower PSI in order to maintain uniform tread contact. Especially if those are M/T tires, because if you run max PSI, they'll be riding on the center tread blocks only, which have zero lateral stability.

They are AT 12 ply 80 lb but have them at 70?

[Wscott52]

:?

Well i am I’m embarrassed to say that on the list i have made of things to check that i have compiled from everyone’s feedback the first was tire pressure.
I failed.
ST trailer Kings max 80lb were only at 50
I swear i checked that but my wife said i tested the truck pressure.
Would that low pressure cause it?

[carringb]

What tire pressure are you running on the truck. Since you're running a considerably wider tire than stock, you should be running a lower PSI in order to maintain uniform tread contact. Especially if those are M/T tires, because if you run max PSI, they'll be riding on the center tread blocks only, which have zero lateral stability.

[Wscott52]

JRscooby wrote:
Is the trailer nose high when hooked up? This can change the caster, make the trailer refuse to track. Of course, that would happen at all speeds, but faster would put more side force on the TV...

Wscott52 wrote:
Just bought it 6 weeks ago.
5 hours home .. scary
60 mile away test camping weekend
And this last weekend 120 miles away is all we have done.

You mean the trailer was MT when you had issues?

MT the first day bringing it home yes, i just figured they slapped WDH on and sent me on my way, so when i got home we loaded it and readjusted everything went to CAT scales. Bought a tongue scale and set it up right just to be disappointed that it was still there.:(

[JRscooby]

Is the trailer nose high when hooked up? This can change the caster, make the trailer refuse to track. Of course, that would happen at all speeds, but faster would put more side force on the TV...

Wscott52 wrote:
Just bought it 6 weeks ago.
5 hours home .. scary
60 mile away test camping weekend
And this last weekend 120 miles away is all we have done.

You mean the trailer was MT when you had issues?

[Wscott52]

Thank you all for these ideas. I am going out in a couple min and start checking and trying them out
I will let you know my findings.
Thank you

[Wscott52]

Just bought it 6 weeks ago.
5 hours home .. scary
60 mile away test camping weekend
And this last weekend 120 miles away is all we have done.

[BenK]

If your shank and ground clearance has room, try dropping the WD hitch head one hole or more

Then go through the setup again


That should end up with your trailer pointed slightly down

Make sure there is a min of 12% tongue weight and your TV sits as the manual says and the tires aired up to max sidewall listed PSI

Are are the WD bars sized for that tongue weight ?

If you haven't, go weigh it, axle by axle. One time with the WD bars tensioned, other not tensioned.

[librty02]

Yeah how far have you towed it so far? Is there any uneven tire wear at all?

[Hondavalk]

Other then a tongue issue maybe your trailer axles are out of a line.

[Wscott52]

librty02 wrote:
Say it ain't so....it's a 3/4 ton it can't have sway issues...lol sorry had to just take a jab at the you can't tow anything unless it's a 1 ton dually crew that's on here....


In all seriousness like said above check your tongue weight loaded with your toys in the back. Take it to the cat scale. A lot of times these toy haulers are tongue heavy empty to compensate for adding weight in the back but some not enough or you just may have to arrange things differently inside. It sounds to me you are under the minimum 10% required tongue weight giving you that sway effect. Also have you messed with the WDH settings at all? A WDH set incorrectly can ruin anyone's towing experience.

Ha ha your badddd

Well,i have no toys it’s just a bunkhouse to us. I have a tongue scale which i have been using every time i hook up. Yea i agree with you about the 10% but the numbers tell me otherwise.
I have spent time with the WDH. I set my unhooked truck at 1 1/2 higher than trailer at level. Then used two washers but when hooked up front end was still too high so i went to three washers which brought my front end down to my beginning height .
I don’t know what else to do other than that. :h

[librty02]

Wscott52 wrote:

carringb wrote:
Have you measured actual tongue weight when loaded? I might simply be unloaded too much once you load the toys in the back.

Sorry i should have mentioned no toys. Just me snoring at night in the bunk.

I’m going to check the trailer suspension and tires. I saw that the trailer king tires are not very good? Maybe better tires?

Oh sorry didn't see that. Hmm that is strange I'd def check the WDH set up. Are the tires TT tires aired to max cold psi? I never had an issue with my trailer kings in the past but my Carlisle Radial HD's do run alot smoother than the trailer kings and with a higher speed rating too.