Vibration (sort of) on some roads

[WherryWillie]

I'm only a few thousand miles into this. I have a 26u towed by a 2016 Ram1500 gas with all the towing options, a Blue Ox hitch. More of these particulars if you want them. Most of the time this rig rolls very nicely. However, on some road surfaces it feels like the trailer brakes are coming on and off at about 100 beats a minute.

We've looked at the trailer on the rear-view monitor, and do not see it pitching up and down. Speed doesn't matter, between 50 and 70 mph, it happens. the frequency does seem to vary in a fashion that it coincides with the road.

The road surface that induces this seems to be a fairly new stretch of concrete interstate-type road. I suspect there is a seam that coincides with some combination of the AS and TV wheels. The recent experience was Wisconsin 29 between Eau Claire and Wausau, but we have hit other stretches in other states and in each case it is fairly new concrete on which there is no visually obvious seams. It doesn't happen with all concrete and never with asphalt, event that with pronounced and regular seams. Sometimes there is a bit of a rocking bounce on a rough road, but it coincides with the bumps and the AS/TV suspension tames it.

All that said, it does not feel like we are bouncing, it feels like somebody is tapping on the brakes, inducing a kind of continuous shudder. I've set the brake gain to 1 (about as low as it goes) and watch the brake indicator. there isn't any indication -- to the degree I understand how to read this -- that the brakes are, in fact, engaging.

I guess my questions are these:
Anybody else experience this?
Can something be done about it?
thanks,

[ROBERT CROSS]

A common occurance

Stream happy...

Bob

[Lumatic]

Probably just regular undulations in the concrete. Concrete can set up a rhythmic vibration when you are towing.Try towing over a section which caused vibration with the brakes disconnected. Also do you hear a rhythmic drumming sound. Probably the road. That should tell you if it is the brakes or the road

[davejay]

Hey
I suspect thou are going the perfect speed, you have the exact amount of lenght, and the weight raio between tower and towed is perfect to set up akind of stevey wonder head bob. Try moving over on to the emergency lane . See if that breaks the pattern. We see this a lot in semis. Tankers are real bad for this, because the fluid gets into a harmonic rythem. It has to do with your lenght. The hitch is hitting a low spot while your trailors or tow unit is hitting a joint in thr concrete. I bet this doesn't happen on a nice asphalt road. If you had a bobble doll or one of those Hawaiian girl dash figureans you would see when this starts to occur. Slowing down or speeding up fixes the proposing effect. I know that stretch of 29 some areas of that road are worse. Weird eh? Maybe a differant contractor built it.

[A W Warn]

Originally Posted by WherryWillie

I'm only a few thousand miles into this. I have a 26u towed by a 2016 Ram1500 gas with all the towing options, a Blue Ox hitch. More of these particulars if you want them. Most of the time this rig rolls very nicely. However, on some road surfaces it feels like the trailer brakes are coming on and off at about 100 beats a minute.

We've looked at the trailer on the rear-view monitor, and do not see it pitching up and down. Speed doesn't matter, between 50 and 70 mph, it happens. the frequency does seem to vary in a fashion that it coincides with the road.

The road surface ... snip... concrete interstate-type road ...snip.. there is no visually obvious seams. It doesn't happen with all concrete and never with asphalt .... snip... does not feel like we are bouncing, it feels like somebody is tapping on the brakes, inducing a kind of continuous shudder. I've set the brake gain to 1 (about as low as it goes) and watch the brake indicator. there isn't any indication -- to the degree I understand how to read this -- that the brakes are, in fact, engaging.

I guess my questions are these:
Anybody else experience this?
Can something be done about it?
thanks,

I'm thinking it may be the vehicle's automatic anti-sway control or the anti-lock brakes.
Undulating concrete would cause porposing

[nwclassic]

Has wheel balance/even tire inflation/proper tongue weight been ruled out?

[m.hony]

We only get the on I-20 in Louisiana so I'm thinking the road itself is a factor.
We only make that bouncy trip once per year.

[Excella1991]

It happens to us traveling on concrete interstate roads in WI. I wonder if freezing and thawing contributes to this. Sometimes speeding up or slowing to find the sweet spot helps.

[WherryWillie]

I appreciate the suggestions. As I noted, it is road specific. Varying the speed does not cause or stop the occurrence, just the speed of it directly proportional to the speed. So, as others suggested, I'm pretty sure there is a seam in the road that is the same interval as TV and AS wheels on the road. I'm going to tinker with all of the above on my next outing. But the most promising suggestions were to tinker with the tension on the WD hitch. Maybe more, maybe less tension. The other came from the RAM dealer who suggested switching off the anti-sway if it happens.

Getting a wheel off the road does make a difference but the cure is worse than the disease. This happens almost exclusively on new, interstate concrete, which is also framed by rumble strips and shoulders with a lot of load debris. This does interupt the vibration, but the instant I return to the road-bed the "vibration" does return.

I also like the idea of getting a bobble-head. Imagine something that cute having a function.
Thanks, all.