Had sway event, what now?

[Sven7777]

We are towing a Flagstaff 25RBS with a 2023 F-150. The truck is rated at #2050 cargo carrying capacity and 10,400 towing. the travel trailer weighs give or take #6,000 fully loaded, with approximately 13% on the hitch. We have weighed truck and trailer at CAT scales so these numbers are pretty close.

The truck has 13,000 miles on it now and over half of that is towing the above trailer with no issues, including a 4,600 mile round trip to Wyoming/ Montana (brutal winds and big rigs running 80mph) with no issues.

The problem actually happened about 20 miles from home, going down a 7% grade on the interstate at 70mph. I generally travel at 67mph but 70 has never been a problem either. I was behind a tractor trailer traveling about the same speed around 6 tractor trailer lengths ahead. Another tractor trailer passed me going down the grade at about 85mph. I commented to my wife that someone must really need those cars he was hauling lol but no issues when he blew by. The problem happened when he got beside the tractor trailer in front of me. The wind/air I was in felt different for lack of a better word. The trailer began to sway, I hit the trailer brakes and the trailer fell back in line behind me but began to sway again as soon as I let off the brake. It took 3 trailer brake applications and we were down to 52mph by the time I had it under control.

We have been using an equalizer hitch and other than that one event it has performed excellent! But now I’m asking myself if this was a rare/ one off occurrence that may never happen again or should I change something about my setup?

[bikendan]

Moved thread from the General Community Discussion section to the Towing, Tow Vehicles and Hitches sub-forum since the OP's questions are specific to that particular sub-forum and not general community questions.

Did you get that 2050lbs payload capacity number from a website or from the actual Tires and Loading yellow sticker, on the driver's door? The sticker that says "Occupants and cargo should not exceed xxxxlbs".

[Bob K4TAX]

I'd say your trailer loaded is closer to 6900 lbs. The hitch weight should be about 900 to 1000 lbs which is transferred to the truck. Don't forget to add in the 100 lbs or so for the actual WDH. With two adults and "stuff" I would say you are very close to the maximum cargo capacity for the truck. That's not unusual.

Two trucks running side by side will create a different vortex width than a single truck. Depending on road terrain, the vortex can bounce off of an embankment and cross back over the road. Your distance behind the trucks can put you inside the vortex or behind the vortex. Visualize the vortex as a rolling wind or horizontal tornado rolling across the ground. (Pilots understand this.)

Make sure the trailer tires are inflated to the correct pressure as well as the tires on the truck. The equalizer hitch may or may not provide sway control. I added a sway bar to our equalizer hitch as the WDH did not provide adequate sway control.

You did all the correct things and took proper corrective action. Scary as heck is it not?

Bob

[dalford]

You say you are using an equalizer hitch. Which one? Is it 4 point with sway control built on?

When I had a tongue pull I used this with an F150 EB and a 27’ Rockwood Mini-Light. I never had a sway issue.

https://www.equalizerhitch.com/produ...l-i-zer-hitch/

[Mokurt]

Originally Posted by Sven7777

going down a 7% grade on the interstate at 70mph.

Sounds kinda fast to me!

[Sven7777]

Sorry for posting in the wrong place originally. Thanks for the replies.

CCC is from door sticker but I’d actually misremembered, it’s #2025 pounds combined weight of occupants and cargo, not #2050.

When we hopped on the CAT scale during a trip this Spring we got
Steer axle 3160lb
Drive axle 3100
Trailer axle 5080
Gross weight 11340

Gas tank was low when we weighed so add another #200 for fuel.Normally truck with family in it is around 5,600 weight at the local trash dump.

Trailer tires are Goodyear in good shape and filled to 65psi. Cold. Truck tires are at 50psi.

We are using the Equalizer 4 point rated #1,000. It’s actually been great in my opinion.

70 probably is a little fast honestly. I don’t normally go over 67 but if it drifts up to 70 going down hill or I need to pass a tractor trailer that finds another 3mph as soon as I get beside him, I’ve never felt uncomfortable going 70 with this setup in the past.

Thanks BOBK4TAX for the comment. I think you are definitely onto something with the vortex theory. The sound and feel of the vehicle actually changes and I could tell something wasn’t right. The actual event was relatively uneventful lol as I was expecting it, as mentioned above, a few moments before it happened so I was ready. I just want to fully understand why it happened and how to prevent it in the future because it could play out totally different next time.

[MGD1961]

Originally Posted by Sven7777

We are towing a Flagstaff 25RBS with a 2023 F-150. The truck is rated at #2050 cargo carrying capacity and 10,400 towing. the travel trailer weighs give or take #6,000 fully loaded, with approximately 13% on the hitch. We have weighed truck and trailer at CAT scales so these numbers are pretty close.

The truck has 13,000 miles on it now and over half of that is towing the above trailer with no issues, including a 4,600 mile round trip to Wyoming/ Montana (brutal winds and big rigs running 80mph) with no issues.

The problem actually happened about 20 miles from home, going down a 7% grade on the interstate at 70mph. I generally travel at 67mph but 70 has never been a problem either. I was behind a tractor trailer traveling about the same speed around 6 tractor trailer lengths ahead. Another tractor trailer passed me going down the grade at about 85mph. I commented to my wife that someone must really need those cars he was hauling lol but no issues when he blew by. The problem happened when he got beside the tractor trailer in front of me. The wind/air I was in felt different for lack of a better word. The trailer began to sway, I hit the trailer brakes and the trailer fell back in line behind me but began to sway again as soon as I let off the brake. It took 3 trailer brake applications and we were down to 52mph by the time I had it under control.

We have been using an equalizer hitch and other than that one event it has performed excellent! But now I’m asking myself if this was a rare/ one off occurrence that may never happen again or should I change something about my setup?

The mention that this was a car trailer passing you may have had something to do with it.

I drove truck for a short time many years ago and often heard on CB that car haulers set up a total different and unpredictable pressure wave and vortex than other trucks.

Even other truckers would complain about it. I don’t know that there’s anything you could’ve done other than what you did.

In my opinion 70 is not too fast. I believe in going the speed limit so others don’t get piled up behind you. It makes others take risks they normally wouldn’t trying to get around you.

[KyDan]

It seems to me you were going a bit fast down a 7% grade but I also think
you had severe wind buffeting rather than fishtail/sway. I hate following
a car hauler trailer. They seem to create the worst slip stream-dirty air-
more than any other type of big rig.

[Mike134]

I have a very similar setup as you 7700 GVWR trailer behind a '19 F150.

Pulled mine for over 22,000 miles so far and the only times it gets "squirrely" is behind a car transport. Like someone said above those trailers must have weird airflow patterns left behind them. Add to that going downhill is more likely to lead to trailer sway then flat towing or uphill and it sounds like you ended up in a perfect storm.

I'd call it a one-off event

Safe travels

[Rhumblefish]

Some thoughts:

Glad you guys are okay, and this didn't lead to something catastrophic. Also, good job keeping your head and using the trailer brakes to get things in line. You clearly know which side should stay "up."

Sway is much more likely at higher speed (more revolutions of the rear tires means more opportunity to be pushed offcourse, setup is more effected by bow wave).

Sway is more likely heading downhill (gravity is working with the trailer, and against you as a driver). Trailer going faster than the TV is a master class in *ohsh*t*

Sway is more likely when the Trailer is as heavy as, or heavier, than the tow vehicle (the reverse is also true, sway is LESS likely then the trailer weighs less than the tow vehicle).

70 at 7% DOWN is fast. Nothing wrong with slowing down - your rig is clearly capable of doing it physically, but as you're more susceptible to sway, it doesn't seem to be a good idea.

I can't speak to vortices coming off car carriers, but it seems like it'd be more confused air, rather than something more predictable than a streamlined semi with a closed van. I can see how that might upset your rig. Add in the impact of the second semi (side by side) and it's not hard to imagine how you have positive pressure on one side of your rig, and negative pressure on the other.

Minus the aerodynamics, your setup actually sounds great and very well matched. I would be interested to see a CAT scale weight WITHOUT the trailer, just to see what the tongue is doing to your setup, but that'd solely be curiosity, and wanting to make sure the tongue weight was good for the weight of your rig.

fwiw, *If* you've got the front passthrough cargo area maxed out and are light out back, you *might* be a little tongue heavy (which can contribute to sway), but that'd have to be a lot of weight. Sweet spot for loading is almost always directly over the rear axles, but can be hard to load there (save for adding liquid to your tankage, depending on where they are. End loading impacts your polar moment of inertia and yields instability, again making the rig more unstable/more susceptible to sway.

Just my .02, hope this helps.

[Brother Les]

Welcome to being on the road with the Big Boys....



Every thing works fine under calm and mild conditions, you just left those conditions.



The setup that you have is fine. The environment conditions changed quickly and they effected you. Equipment... ok... and I mean, just ok.... Those other trucks were pushing you around and you must compensate for that. This will happen again 'sometime' down the road (if you do a lot of driving).



Even if you were going 40mph and being passed like that you would you would have been 'moved' around. Nature of physics. Learn from it and be ready. A lot of driving is looking in the mirror and knowing what is coming up behind you and around you.


I (myself) have no problem with driving 60-65 mph and will drive 60mph all day long and enjoy the travel.

[5picker]

Glad you reacted properly and all faired well.

A couple points... you mentioned the two trucks ahead of you were about 6 tractor trailer lengths in front of you when this happened. That's a considerable distance but I suspect you were just on the 'tail end" of the draft they were creating. Just where their air they were opening (and started to close) and the air you were opening, joined. Using your brakes a few times and slowing down, got you far enough behind to where things calmed down air wise. I'm not sure any of this was caused by improperly operating weight distribution. We've encountered this a few times, often in passages where there are mountains on both sides of the road and you get a "tunnel" effect. I've seen semi's experience this too when a odd-ball piece of equipment passes them. Since moving to towing 5th wheel trailers about 35 years ago, those experiences are almost never an occurrence anymore.

One last thing... I know there are those on this forum who believe if one doesn't run the posted speed limit, they are a hinderance to other traffic but I don't share that thought.

There's much debate on this but the posted speed limit is just that... the "limit." It does not mean you MUST go that fast. So, unless there is a MINIMUM speed limit posted, one is free to run whatever speed one can comfortably control their rig. If one is not able to maintain the MINIUM speed limit, then they either need a different rig or need to stay off the roads.

[Bob K4TAX]

Driving on a multiland road, i.e. interstate, I will always hang in the rightmost travel lane, a bit below the posted speed limit. If those behind me want to pass, the show-out lanes are to the left. Have at it.

Down a 7% grade or greater is not advisable to run the speed limit. Most vehicles towing a bumper tow or a 5th wheel should be running at truck speed limits and not passenger car speed limits. And when encountering "truck right lane only", be sure that does include TT and 5th wheels.

What exact laws are enforced is not the driver's choice. But it is the driver's common sense that matters.

Bob

From an earlier post:
"One last thing... I know there are those on this forum who believe if one doesn't run the posted speed limit, they are a hinderance to other traffic but I don't share that thought.

There's much debate on this but the posted speed limit is just that... the "limit." It does not mean you MUST go that fast. So, unless there is a MINIMUM speed limit posted, one is free to run whatever speed one can comfortably control their rig. If one is not able to maintain the MINIUM speed limit, then they either need a different rig or need to stay off the roads."

[Aussieguy]

Originally Posted by Bob K4TAX

Driving on a multiland road, i.e. interstate, I will always hang in the rightmost travel lane, a bit below the posted speed limit. If those behind me want to pass, the show-out lanes are to the left. Have at it.

Down a 7% grade or greater is not advisable to run the speed limit. Most vehicles towing a bumper tow or a 5th wheel should be running at truck speed limits and not passenger car speed limits. And when encountering "truck right lane only", be sure that does include TT and 5th wheels.

What exact laws are enforced is not the driver's choice. But it is the driver's common sense that matters.

Bob

From an earlier post:
"One last thing... I know there are those on this forum who believe if one doesn't run the posted speed limit, they are a hinderance to other traffic but I don't share that thought.

There's much debate on this but the posted speed limit is just that... the "limit." It does not mean you MUST go that fast. So, unless there is a MINIMUM speed limit posted, one is free to run whatever speed one can comfortably control their rig. If one is not able to maintain the MINIUM speed limit, then they either need a different rig or need to stay off the roads."

X 2 wise words for all

[SailorSam20500]

My 2 cents.
Your Equlaizer is a very good sway CONTROL hitch. It will do the job most of the time. If you want to move up the ladder in reducing the possibility of again having a similar experience, get a Propride or Hensley hitch.
Equalizers control the pivot that occurs at the hitch ball. Propride and Hensley prevent the trailer from initiating a pivot at the ball.
This u-tube from Hensley demonstrates:

https://www.youtube.com/watch?v=hWKVs04Xy8I

At this point in time, I think Propride makes the better version of this hitch design.

[Aussieguy]

I would not change much for a one off event other than my speed
especially going downhill (as noted by others)

sooner or later something big will pass you or the a crosswind will come out of nowhere.

Think of those pesky dust devils... they look kinda nice and weird ... but drive into one at 60mph as it crosses the road and you will need to change certain items of under clothing
(Yes... we did it once and won't be doing it again)

what YOU do is more important...
got your brakes in good order... controller adjusted?
Did you ever practice using the controller so you can find the slider easily?

leave enough room in front so you can increase your throttle just a bit when you feel that push from a friendly semi...

Older tow vehicles... check suspension/steering components as they wear out you kinda get use to the slop
replace the shocks or joints and you marvel at how good the truck drives....

[Reverse_snowbird]

I agree with it being a 'one off' event. You handled it well.

Welcome to the forum!

[llr]

Originally Posted by SailorSam20500

My 2 cents.
Your Equlaizer is a very good sway CONTROL hitch. It will do the job most of the time. If you want to move up the ladder in reducing the possibility of again having a similar experience, get a Propride or Hensley hitch.
Equalizers control the pivot that occurs at the hitch ball. Propride and Hensley prevent the trailer from initiating a pivot at the ball.
This u-tube from Hensley demonstrates:

At this point in time, I think Propride makes the better version of this hitch design.

I agree, I got one for my prior TT after a couple of sway events, towed ok 90%+ of the time. One thing I was surprised was how much better the overall tow was. I was making a look more minor corrections then I ever noticed. I would not go back to a TT without a pro pride.

[Tex94]

Originally Posted by llr

I agree, I got one for my prior TT after a couple of sway events, towed ok 90%+ of the time. One thing I was surprised was how much better the overall tow was. I was making a look more minor corrections then I ever noticed. I would not go back to a TT without a pro pride.

X3 with these guys. Keep your numbers right like you have them and add this in. I have a 22 f150 and a 22 2509s I think the sister of your trailer.

[D W]

That's not sway. That's "aero-push". You got caught in an air wash from the two trucks traveling together. The wall of air that the two truck are pushing through goes around the trucks and makes for severe turbulence when when the air from the left and right meet behind the trucks. Your RV is far from aerodynamically correct and the turbulence will just toss it around. There's no amount of sway control that's going to prevent this. The only thing you can do is let up and slow down. Because you can drive 70 mph doesn't make it a good idea.