Vibration when towing my TT between 50 & 55

Yesterday I was towing my 5000lb travel trailer to the dealer for a few repairs and when the speed was between 50 and 55MPH I felt a vibration in the steering wheel. At slower and faster speeds no vibration. Also when not towing no vibration at any speed.

So does anyone have a idea what is causing the vibration. I'm at a loss.

Thanks for your help.

A. Cheap Chinese tires.
B. Tires and wheels not balanced.
C. Brake drums are not balanced.
D. Tires are damaged.

I would think that if the vibration was coming from your TT you would feel it in the seat of your pants too. What about the weight of the TT  on the back of your tow vehicle compressing your suspension and causing a vibration from some of your steering components?  Do you have a weight distributing hitch on your TT? It is set properly to keep from unloading the weight from the front axle of the tow vehicle?

SargeW,

I have a equalizer 4 point WDH and it is set correctly. I did not feel it in the set.

Lynnmor,

The unusual thing about this trip to the dealer is I have towed the trailer 1200 miles around the state and have not in the past noticed this vibration.

Strong winds and rumble strips.

I was on a curvy windy 4 lane road of heavy thick moving traffic, and the guy towing was in the lane left of me, his trailer kept blowing over into my lane and I was honking trying to get his attention. I slowed way down, making the folks behind me mad and I could see the guy's trailer kept blowing over into the side of the right lane. It was a blustery day too.

I've seen trailers and boats that seem to blow over to the rumble strips. No idea if that happened to you and your speed just happened to be in the 50's.

Not balanced tires or out of alignment front end.

RVRAC said:

Not balanced tires or out of alignment front end.

Click to expand...

Agree.  Because the WD hitch shifts weight to the front-end and sets up different weight conditions, you might not notice the vibration or it may occur at different speeds without the TT.

Thanks for all the comments. I'll look into balancing the tires.

many years ago, I used to do vibration analysis of industrial rotating equipment.

I remember a teacher in one of the seminars I attended going on on on with his side track stories..... his adventures being a predictive maintenance consultant.

One of the stories he was so very proud of, was some car suspension work he did.  I think it might have been done as part of a law suit

anyway, we were learning about natural frequencies of mechanical systems.... ie. the frequency that they naturally "want" to vibrate, or excite.... like a bell has a natural frequency at which it vibrates the best... mechanical systems have a natural frequency, and when an external vibration excites the system at that frequency, or a harmonic of it, the vibration can be very much worse than when excited at other frequencies....

Anyway, this guy's story involved some car and he took high speed video of the wheel while simultaneously measuring the vibration amplitudes....
there would be a slight excitation from say an imbalance
but when a certain speed was reached
let's say between 55mph and 60mph the system would be excited
and in this case
so he said
the wheel would fly off the ground once per rev.
and that speed was later calculated to be at the system's natural frequency

bad design.  Would have been better to design it so the natural frequency is outside of the range of normal driving.

now I didn't see the video or data, it was just a story

But I have had a few cars, one that had a bent wheel, that would shake the steering wheel badly between 55-60mph, but would be rather smooth faster or slower.

A U-joint vibration is a much higher vibration than most any other vibration on a drive train, much like the speed of a rumble strip.

Bill