Bouncing on the freeway

[wi-steve]

Hello all,

I have a 2015 Dodge Durango RT, 2017 Jay Feather 25BH, and just installed a Centerline TS 32217 Weight Distributing hitch.

Without the WDH, the rig was not stable over 55 mph.

The WDH took helped with the squat, the truck is now just no more than a half inch lower in rear when the trailer is hooked up. The WDH hitch helps quite a bit on asphalt, much more comfortable to drive on state roads at 55 to 60 mph.

I tried it out on the freeway, but found that the concrete with it's pattern of up/down undulations caused the trailer to want to bounce excessively at 50 to 55 mph. I don't know if it would go away at higher speeds, I felt it was unsafe and drive slower.

Does anyone have suggestions as to any adjustments in the setup could reduce the bouncing on concrete (short of buying a pickup, which I plan to eventually do as soon as possible)?

Tongue weight and overall trailer weight (loaded with gear) are towards the high end of what the Durango is rated for, but should be within the limits.

Thanks
Steve

[Sundancer330]

Probably not much you can do, the Durango has a pretty soft suspension and when you are near max weight between it and the TT you will get the bouncing.

[Midnightmoon]

Originally Posted by wi-steve

short of buying a pickup, which I plan to eventually do as soon as possible?

There is a section of RT-81 northbound in PA outside of Hazleton that will just about destroy your kidneys with my current truck and trailer, and believe me, I have plenty of truck to handle my towing duties. It is entirely due to the spacing of the joints in the concrete and the harmonic bouncing is just terrible with my truck/trailer on that section of road. It was so bad last summer, that I actually pulled over twice to make sure that nothing was broken causing the problem.

Anyway, my point is that it there may not actually be anything wrong per say with your setup. Rather, just a combination of your tow vehicle/trailer combo and that section of roadway.

The new truck that you buy obviously may do better on that section of road, but even trucks are not immune to that issue.

[Rustic Eagle]

Originally Posted by wi-steve

snip..... Does anyone have suggestions as to any adjustments in the setup could reduce the bouncing on concrete....snip

Is your WDH rated adequately for the TT's loaded tongue weight?

The WDH's main design function is to address the TV's front suspension integrity (weight), once adjusted properly the TV's rear suspension's degree of squat is just a by-product of the TV's front suspension weight return requirements

The best way to optimize the adjustment of a properly rated WDH is a visit to one's local CAT scale.

CAT Scale how-to: https://www.jaycoowners.com/forums/f...v-tt-3871.html

Also, confirm that all tires are inflated to specified towing psi, and confirm the condition of your TV's shocks.

Just some food for thought.

Bob

[PlayersZ28]

My fiver behind the dually would bounce at certain speeds on the concrete highways. It would also do it when I was driving just the truck. I figured it was the drainage cuts that are made across the roadbed. If I sped up or slowed down it would go away, 60mph was the wrong speed for most concrete roadbeds, likely based on the WB of the truck. My Chev doesn't do it though. The south end of the toll road thru OK was real bad though and caused porpoising.

[Kahoneys]

Length of wheel base has A LOT to do with the bounce also. The Durango has a very short Wheel Base.

[wags999]

Originally Posted by Midnightmoon

There is a section of RT-81 northbound in PA outside of Hazleton that will just about destroy your kidneys with my current truck and trailer, and believe me, I have plenty of truck to handle my towing duties. It is entirely due to the spacing of the joints in the concrete and the harmonic bouncing is just terrible with my truck/trailer on that section of road. It was so bad last summer, that I actually pulled over twice to make sure that nothing was broken causing the problem.

Anyway, my point is that it there may not actually be anything wrong per say with your setup. Rather, just a combination of your tow vehicle/trailer combo and that section of roadway.

The new truck that you buy obviously may do better on that section of road, but even trucks are not immune to that issue.

X2
Harmonic bouncing.. you never get it on asphalt, and only on certain concrete roads.

[Cannon]

Air bags could help stiffen it up and their pretty cheap.

[DanNJanice]

Probably very little will help the situation.
It is caused by the combination of the height of the expansion cracks, the distance between cracks, and the truck/trailers wheelbase.
I had this happen so bad one time, on I-5 north of Seattle, that the wife (who was wearing a sweatshirt) made me stop so she could put on a bra.
Another road that I found it really bad on was HW20 eastbound from the western boarder of Iowa. I diverted south and I-80 was much better.

[suzieshome]

This a a problem with concrete and the expansion joints. Doesn’t matter If you are towing or not. If you change your speed up and down it will break the pattern. Or stay off the interstate

[Jblack]

I have a 3500 SRW, so completely different truck, but would also have this issue somewhat. I started towing with a full load of water (you may not have the capacity for this) and my bounce went away. Plus I am good to go if the parks water supply is down.

[JohnWedell]

You May want to talk to someone about shocks maybe a better pair of shocks might help a little with the bouncing

[rodro123]

I get the bouncing on some concrete roads. But it is only on old warn concrete roads never on newly poured concrete. Sometimes trying other lanes helps a little. Once it starts to bounce I slow to 55mph. It’s so bad you can’t drink coffee and drive.

[NH_camper]

Out of 5 campers, I've only had 1 that had the dreaded harmonic bounce on concrete roads. It was my first one. I tried everything to no avail. It seemed I had 2 solutions, trade either my TT or TV. I traded both.

If this ever happens to me again, I think I'll look into retrofitting the trailer with shocks. Here's a link with pictures:
https://www.rv.net/forum/index.cfm/f...d/tid/23731728

[PMC]

A good quality set of heavy duty shocks and airbags to stiffen it up will help but likely won't eliminate it. We had similar issues with our 27DSRL which was similar in weight and size (and actually layout). I'd probably take it to a cat scale and see what your weights look like and go from there. Take a close look at how it's riding (level vs nose up/down) and try adjusting that and possibly how you load it (make sure you're not adding too much to the rear or front).

There are just some roads that are going to bounce you with a bumper pull. My main nemesis in MN was 52 south of Cannon Falls which happens to be a road I'm on with the TT on a fairly regular basis. First pull with the 27DSRL and our F150 down that stretch and I couldn't believe how jarring the bounce was. We added airbags to stiffen it up which took some bounce out of it out but didn't eliminate it. A couple years later we moved to a 1 ton diesel truck and again it was much smoother but still noticeable.

[norty1]

We get that on our fifth wheel on those poured concrete slab interstates. The slabs tilt slightly and the joint start the rig bouncing. Often a slight increase or decrease in speed will help.

[SkyBound]

I tow at the max payload of my truck often and have experienced a bit of porpoising especially in the back end while going down some bumpy roads. LT tires helped, a rear suspension enhancer helped, and I am in the process of upgrading the shocks. These are little things you can do in addition to making sure your hitch is set up correctly.

[jsallman1]

Shocks on the trailer and upgraded shocks on the truck made it significantly better, but not eliminated for us. Change from a 1/2 to 3/4 TV did not solve it either. As others have said, changing weight, adding or draining water can help but it’s a bit specific to the stretch of road you are on, fix it for one stretch you will find another. I just upgraded hitches to an easily adjustable WD bar tension (propride), I am hopeful that when I hit this issue now I can just get out and stiffen or loosen the tension between the truck and trailer with a power drill and drive on. I am really hopeful I won’t have it, but guessing that won’t be the case [emoji6]


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[33 RLDS]

Originally Posted by Midnightmoon

There is a section of RT-81 northbound in PA outside of Hazleton that will just about destroy your kidneys with my current truck and trailer, and believe me, I have plenty of truck to handle my towing duties. It is entirely due to the spacing of the joints in the concrete and the harmonic bouncing is just terrible with my truck/trailer on that section of road. It was so bad last summer, that I actually pulled over twice to make sure that nothing was broken causing the problem.

Anyway, my point is that it there may not actually be anything wrong per say with your setup. Rather, just a combination of your tow vehicle/trailer combo and that section of roadway.

The new truck that you buy obviously may do better on that section of road, but even trucks are not immune to that issue.

I think I know the exact spot you are talking about. I remember from our Disney trip in 2016. I was glad to get past it

[Midnightmoon]

Originally Posted by 33 RLDS

I think I know the exact spot you are talking about. I remember from our Disney trip in 2016. I was glad to get past it

I run to Binghamton quite a bit. I'm seriously considering running 220/15 north to 17 and taking it east instead of 81 again with the trailer. It really is that bad.