New Owner with a Herky Jerky Ride! Help!

I have been lurking here for a couple of months and my wife and I decided to take the plunge and buy a Trailmanor! We picked up our used 98 2518 yesterday. We love it! It is a really sweet camper and we look forward to going camping.

We do have a big concern with towing it though. We have an 05 Honda Odyssey which can easily tow this lightweight trailer. Honda put in the coolers we need and the dealer installed a Reese Class III hitch with a 6000 lb WDH.

However, when we travel on the highway with concrete seams in it (most highways in PA!), the van gives a herky jerky, front and back movement at speeds over 40-45 mph! It is so bad that you can't speak right! If the road is smooth asphalt, it doesn't happen, only on bad concrete roads with evenly spaced seams.

The dealer drove around with us and thought that much of what we felt was normal. They did replace the brake shoes, check the drums and bearings, and install a new plug (to be sure there wasn't an electrical problem with the brakes). This didn't help. They also took the chains on the WDH up one link to move the weight a little more forward. This helped a little.

Any ideas? I don't think we could drive more than an hour is the van is going to be jerking around like this.

Could this be some weird harmonic thing going on? Will this hurt the transmission?

Thanks,

Dean

Dean
If this is what I think, you are operating at a resonant frequency of the TM & TV. That means, it is bouncing up & down like a spring. You should be able to change speed to not feed the "system" at the resonant frequency. By slowing or speeding you can move to a higher or lower frequency and the amount of bouncing should decrease.

That's techie talk, I guess. Just remember to change speeds, either up or down next time that happens and see if the ride doesn't smoothen out. I am sure that you don't have this at say 10 to 30 MPH. Maybe it peaks at 50 or 60. The speed will depend on the spacing of the stripes in the concrete, so speed may have to change on another section of highway.

Sorry to hear this. Check back if it doesn't cut down with these tactics.

Another thing is your TV shocks. They dampen this kind of action. If your shocks are bad (OEM 5 or so years old) that could well be the cause.

[Denny_A]

I towed a 2720SL with an '01 Odyssey. Same problem in Wisconsin on its concrete hiways. Especially Hwy 151, Oshkosh (B'gosh) to Madison. It was worst at the speed limit. I had to be 15 mph UNDER the speed limit to keep the coffee in my cup. Tried dropping another link once, but it only slightly affected the problem.

Later I drove the same roads, towing the same trailler, using a Toyota 4Runner. Same problem, but not as vertigo-inducing as with the Odyssey.

So, I think the primary problem is the road + the compliance of the Ody's suspension. Since your trailer's tires are probably speed-limited to 65 mph, decreasing speed, to get out of the peak resonance regime, seems to be the only solution (short of using other roads).


Denny_A

When I brought my new 2720 home I too noticed that it bucked like a bronco more than I thought it should. I have a relatively long wheel base and plenty of carrying capacity with my crew cab and 6 foot bed. The initial suggestions here on the TMO board were a WD hitch and/or new shocks.

Actually, all I needed to do was inflate the tires a little more. I had never actually checked the pressure. They seemed hard enough to the touch. It turns out I was running 50 psi. I now run 70-75 and all is well. Tire is rated for 80.

I recommend you start with the cheap stuff and work your way up. Air is free. Shocks are pretty cheap.

I do agree that harmonic oscillation is a likely culprit. Try to find an equally bumby road, but one where the distance between the bumps is different. That should result in the same problem, but at a different speed.

One of the examples used in an engineering class many years ago was a new design for a railroad flat car that came out. It had the unfortunate property of derailing if they rode at a particular speed for too long. The problem was that the distance between the front and rear wheels was the same as the distance between rail joints. 33 feet as I recall. Rail joints are evenly staggard. At a particular speed both the front and rear wheels are bumped upwards on one side. Then the same happens on the other side. It is like pushing a kid on a swing. As long as you use the right rithym you can get the kid very high with almost no effort.

Any road with equally spaced bumps can trigger the same problem when towing a trialer. Faster might be better, but be careful getting there.

THey are all right! We had the same thing happen in NY State from Albany most of the way across to Erie on the southern route with a travel trailer last year. THis year it was better with the TM when paired with a Mercury Mountaineer. It is the combination of wheelbases you have. Annoying but probably not a catastrophy. Queeniereads aka Judi

Thanks for all the suggestions. I too, thought about air pressure. I will try increasing it slightly. Would decreasing it make it better or worse? How low should I go? I think the dealer said to run with 60 psi.

[Denny_A]

Originally Posted by camp_in_pa

Thanks for all the suggestions. I too, thought about air pressure. I will try increasing it slightly. Would decreasing it make it better or worse? How low should I go? I think the dealer said to run with 60 psi.

...... is lmited to 50 psi cold. Increasing to 60 could be asking for trouble. This statement assumes your 60 psi was referring to Goodyear 14" trailer tires. If in fact you meant the tow vehicle then (...as leticia would say...) nevermind!

Denny_A

Just a clarification on my previous comment.

It was my TV tire pressure that was low. That allowed too much flex, thus the bouncing.

I would try maxing out the rated pressure for the TM tires (should be 50) and at least the rear of the TV. I'm not sure how much bounce would occur from under inflated front tires but I would guess that the TV rear tires are much more critical.


Car manufactures are sometimes accused of specifying too low of a tire pressure on the door. The claim is that they write the spec for a soft comfortable ride. Check the rating on the sidewall of the TV tires. Probably higher than what the label in the TV door says.

[Denny_A]

Originally Posted by PopBeavers

Just a clarification on my previous comment.

It was my TV tire pressure that was low. That allowed too much flex, thus the bouncing.

I would try maxing out the rated pressure for the TM tires (should be 50) and at least the rear of the TV. I'm not sure how much bounce would occur from under inflated front tires but I would guess that the TV rear tires are much more critical.


Car manufactures are sometimes accused of specifying too low of a tire pressure on the door. The claim is that they write the spec for a soft comfortable ride. Check the rating on the sidewall of the TV tires. Probably higher than what the label in the TV door says.

In fact, if one uses the max pressure indicated on the tires sidewall the following benefits will be realized:

1. Delayed onset of hydroplaning. Hydroplaning speed is, by rule of thumb, 9 x Sqrt of tire press. At 32 psi; 9 x Sqrt 32 = 51 mph. At 60 psi, 9 x sqrt 60 = 70 mph.

2. Handling improves. Less understeer; i.e., greater control.

3. [Errata...Braking degraded. Smaller tire surface area in contact with the road.] Braking is NOT degraded. My original sources were in error; therefore am I. Braking performance is better, wet and dry, at higher tire pressures. Here's a link:

http://www.nhtsa.dot.gov/cars/rules/...FEA/TPMS3.html

Scroll to charts at end of the long dissertation.

4. Stiffer sidewalls means less flexing, thus reduced heat generation. Tires will last longer.

5. Inproved fuel efficiency (reduced rolling resistance).

I infate my Prius tires to 44 front and 42 psi rear. Sidewall has 44 psi max stamped on it!

So, there is no downside to running with the highest allowable tire pressure (unless your false teeth aren't tightly fixed )! If the rear tire pressures are increased, the front should also be increased. Otherwise a handling problem can develop. Front understeering while rear tires provide greater traction. Also a braking inbalance when the front dives, transferring wt fwd, during hard braking.

Denny_A

On RV.net I have found several postings where various tire manufacturers web sites report optimum tire pressure as a function of weight being carried. Just weigh each axle and then look up the pressure to use.

However, I have never found a similar chart for my TV Dunlaps.

I can think of two reasons to run lower than normal tire pressure:

1. Sand. At the beach it is common to reduce tire pressure to increase surface area contact. Of course speeds are quite low. 15-25mph

2. Certain dirt roads that I have encountered have what could best be described as tread marks from a caterpillar tractor. They go on for dozens of miles. Hard tires tend to skip like a rock. Steering is non existent. Reducing tire pressure improves steering.

These are both very unusul exceptions.

I run hard tires when towing and then (sometimes remember to) soften them up a little for my daily commute.