We just finished our fourth trip with our new trailer. Been camping for years with a smaller trailer, but just moved to a 31'. I have a situation that I need to figure out when we are on roads that are concrete with expansion joints. It doesn't happen on asphalt paved roads. On the roads with expansion joints every few feet if I'm driving at more than about 50 MPH the tow vehicle starts bouncing. The trailer doesn't seem to sway. It just goes from a smooth ride on asphalt to bouncing so hard we can't hold a conversation until I get it under control by slowing down. It feels very dangerous. I had a about 20 miles on it on this trip. Part of the time I was doing 50 and traffic around me was doing 80. That seems dangerous, too.Tow vehicle is a 2018 Chevy Silverado 1500 with the max trailering package. Tow capacity is supposed to be 11,000 pounds. My trailer weighs 7,300 pounds. Any suggestions as to how to deal with this? The max trailering package is supposed to have a stiffer suspension. Would stiffening the suspension even more help with something like this?Thanks for any advice.DanI just realized I posted this in Toy Haulers. My trailer isn't a toy hauler. Just made a mistake, and I don't know how to move the post!

Maybe tightening the springer bars could help. Mine bounces a little on concrete. but not so much as to bother me.

Have you weighed your trailer and tow what is you pin weight.

Thanks for the quick response. Is that the bars that extend back from the hitch on the weight distribution hitch? My hitch is an Equal-i-zer, I believe. I guess I would adjust the piece mounted on the trailer to make the bars sit higher?

Stickdog, you're going to make me show how little I know! I did weigh it, but don't remember everything I thought I knew at the time! The truck by itself (trailer not attached) was 5,980. The truck with the trailer attached but trailer off the scale was 6,940. So, is my pin weight the difference in those two? The trailer weighs 7,200 lbs.Actually, those numbers are for my original tow vehicle. I recently traded a 2014 Chevy 1500 for a 2018 Chevy 1500. Both trucks did the same thing.

Moved from Toy Haulers to Towing

Bouncing on Concrete Roads | Good Sam Community

dozment
Explorer
Apr 09, 2018
coolmom42 wrote:
I'm thinking all of the trailer bounce is being transferred to the truck through the hitch. The only thing I can think of that would help is stiffening the truck suspension somehow (although that might make it WORSE).

Or you could find an alternative route as soon as possible. Trouble is these stretches of road appear with no warning.

I found a post here quoting Les Adams talking about setting up a weight distribution hitch. I want to go through his steps on mine. I haven't measured it, but I do believe the front end is a little higher when the trailer is attached.

As for those stretches of road appearing without warning, I'll be talking with my buddy the roadway engineer!
lawrosa
Explorer
Apr 09, 2018
Im sure they fixed the weld issues with the chevy hitches...
valhalla360
Navigator
Apr 09, 2018
If it's smooth on most roads and only happens on concrete roads where the joints are at relatively short spacing (15-20'), it's most likely just matching the harmonics of the wheel base.

It's kind of like pushing someone on a swing. If you time the pushes, it takes very little effort to get someone swinging quite high.

In the same way, if the speed and spacing match up, as the suspension comes down and starts to push the truck frame up...at the same time you hit the next bump adding to the upward push...this gets repeated until it feels like you are going to go airborne. If you slow down, the harmonics are lost and the ride smooths out.

I know a few roads like that. I try to avoid them. Also on a couple, it's only one lane that has the issue as they did a lot of patch work in the right lane but not in the left. If traffic isn't too busy, I'll just move into the left lane for a smoother ride.
73guna
Explorer
Apr 09, 2018
I experienced this porpoising or bucking on various stretches of road going through Iowa and Michigan last year. Pretty darn annoying to say the least.
Might try tightening the bars up a bit.
Your gonna run into this on some stretches of road.
May be more severe in a 1500
2112
Explorer II
Apr 09, 2018
Timbrens will help dampen the bounce, bring your front end down and improve the overall ride
LarryJM
Explorer II
Apr 09, 2018
IMO the bouncing is all about the harmonics between the expansion joint spacing and the your speed with the TV to Trailer wheel base spacing the third factor along with the wheelbase of the TV as a fourth minor factor. The only thing you can do is to change one of those to get out of that harmonic and the only one you can change is your speed.

There is a stretch of I-4 just west of Orlando where mine is extremely bad and happens every time I hit that stretch of road that is around 2 to 3 miles. I've experienced it in other areas, but not too bad and a change of around 5 to 10 mph slower always cures it for me at least. The key is to recognize it's onset and IMMEDIATELY slow down so the harmonic amplitude doesn't get too bad.

Larry
dodge_guy
Explorer II
Apr 09, 2018
Yep I get that bouncing also. Only on certain concrete highways. not much you can do but speed up or slow down to find where it does it the least. I have air bags with the controller in the center console. what I do is add air to the bags until the bouncing is lessened! what this does is takes some of the tension off the WD bars which changes the harmonics.

what`s worse is most of these are toll roads that we have to pay for!
evanrem
Explorer II
Apr 09, 2018
its mainly the roads but a softer suspension an loaded heavy also plays into it i think. My 1500 was the same way after upgrading the truck to a 2500 it got better but you can still feel it.
Dick_B
Explorer
Apr 09, 2018
I wrote to the man in charge of all concrete highways and suggested the spacing should be varied instead of all the same. Must have been too revolutionary since I think they are still made the same way.
The only thing I can suggest is to either speed up or slow down to eliminate the sympathetic vibration of your rig with the highway.
Lynnmor
Explorer
Apr 09, 2018
I have noticed that the worst of these roads have each segment tilted a bit. It's not just the spacing causing the problem. One particular road had the problem from new with each section mismatched to the next. After several years of abuse, the slabs were milled for a better match.

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