Trailer Road Resonance

[AlibyOK]

I am towing my 2619 with my 2011 AWD Toyota Sienna. It has a weight distribution hitch and a P2 brake controller.

I found last weekend that the trailer began to tug cyclically at the car as soon as we got onto the section of the highway that was constructed of typical concrete slabs. If I went at 60 mph it was gone, but at 55 mph it was target jarring.

At one stage I thought our may be brakes that were causing it, but I am certain that out was the undulations of the road.

Has anyone else experienced that and if so are the ways to mitigate it. It certainly can't be good for the vehicle/trailer and it definitely made us shook feel rather ill.

[Riwright]

The phenomenon is called "chucking." I had a problem with it when I towed a trailer too heavy for a Lexus RX300.

You need to get it fixed, it is dangerous. That kind of yanking will tear the transmission out of the car -- or perhaps do something worse.

The trailer shop I took the rig to said that he suspected that the tongue weight was too high and that the frame was flexing under the load.

We never verified this or worked through the problem. I decided to trade for a pickup which has worked out great.

If you can get the trailer to a set of scales safely, weigh it and get the weight of all three axles both with and without the weight distributing hitch engaged. Search the threads here and you will find a lot of data on how to weigh.

These numbers will give a place to start on getting to a rig that you can tow safely.

You want to make sure the trailer is light enough for the vehicle and that the tongue weight is not too high. It might be that a simple adjustment of the chains will get it sorted out, or it could be you need to lighten the trailer or get a heavier vehicle.

In any case you are close to the limits towing with a Sienna so you will need to make sure everything is right.

Also run a search for "Sienna" as I believe there is at least one person here who tows with one.

[Mr. Adventure]

This problem can be caused by the WDH being set too tight, so that you're enjoying every bump a little too much on all 3 axles. Start by measuring the front fender to road distance on level pavement hitched and unhitched. You'll want these to be about the same to put you in the ballpark until you can get to a truck scale for more exact numbers.

This link tells you how to do that and gives you a spreadsheet for the calculations: http://www.trailmanorowners.com/foru...ad.php?t=12552

[Mr. Adventure]

Originally Posted by Riwright

The phenomenon is called "chucking." I had a problem with it when I towed a trailer too heavy for a Lexus RX300...

I've owned quite a few RV's over the years, and heavy is great until you find something heavier, until eventually it's all so heavy that it's too heavy and expensive to want to move it at all. These days I'm very fond of the idea of towing my RV with my daily driver.

Everyone makes their own decisions, and I don't fault yours. Depending on where you tow and go, more tow vehicle can be a very good answer. But your repair guy is way over his head when he offers those ideas about flexing the body and suggesting that chucking has something to do with the transmission. Most likely he doesn't tow and doesn't know.

G E T - A - T R U C K.....

I'm sorry. Too much coffee this morning...

I have to stir up trouble where I can.

[Brittany Dogs]

Wait a minute guys, while I will certainly agree that a bigger tow vehicle is always better, the problem is said to only happen where there are concrete slab highways. If the problem does not happen otherwise, then I tend to think it is just a problem with the tow vehicle dancing with the trailer on the dance floor.

Just go to a different dance floor.

[mjlaupp]

Originally Posted by AlibyOK

I am towing my 2619 with my 2011 AWD Toyota Sienna. It has a weight distribution hitch and a P2 brake controller.....

....I found last weekend that the trailer began to tug cyclically at the car as soon as we got onto the section of the highway that was constructed of typical concrete slabs. If I went at 60 mph it was gone, but at 55 mph it was target jarring.....

First of all. No matter what you do to the TV/TM combination, you will always have a chucking problem on this section of highway at 55 mph. The chucking is a result of the wheel base of the Senna and the distance between the Senna rear axle and the TM axle. So don't drive at 55 mph or get a different tow vehicle. Note that a tow vehicle with a different wheel base will also have this problem but at a different speed.

What can you do with what you have?

Weigh the Senna and 2619 as suggested Mr. Adventure above. The tongue weight of the TM should be 15-17% of the Gross Vehicle Weight of the TM. Adjust by repacking the TM. Also avoid packing heavy in the back of the Senna.

Double check the WDH settings as suggested by Mr. Adventure above.

Make sure the Senna tires (at least the rears) are inflated to the max rating on the tire side wall while towing. Upgrade to LT tires?

Upgrade the rear shocks on the Senna to heavy duty air charged shocks. Your existing shocks may be ok when lightly loaded but can't handle the extra dynamic load while towing.

If the 2619 has 14 inch tires, make sure they are inflated to the max setting on the tire sidewall (50#). 15 inch tires on this size TM should be inflated to at least 55#.

Originally Posted by Brittany Dogs

...
Just go to a different dance floor.

There you go!

We had something similar happen on some concrete pavement when towing with our earlier 4x4 Tacoma. Sort of a resonant bouncing that was almost sickening. Didn't feel too dangerous though ... seemed like the Tacoma could handle it. And it only happened once or twice over 10,000 miles.

Hasn't happened yet with our F150 which may be due to a softer suspension (4x2), longer wheelbase, and heavier weight. Or maybe we just haven't met that particular piece of pavement yet.

[MudDog]

We towed with a Sienna for over a year before going to the Tacoma.

We had the same issue towing home from the dealer and on the first trip after that. The next trip I checked and adjusted my WDH setup 1 link tighter and never had the issue again.

The Tacoma can handle more tongue weight, so we backed off a link we when switched to the Tacoma.

Several on-line guides (including some on this forum) on how to properly adjust the WDH.

Not much margin with the Sienna, so your optimal WDH settings may vary from trip to trip depending on the load in your Van and TM load.

Certainly make sure your hitch is set right. But I think that is not the problem.

I don't use a WDH, never have. But I've experienced exactly what the OP describes. So while it might be a WDH set too aggressively, it very well may not be.

I have towed with a 3/4 ton short box diesel and had exactly this problem. And with a 3/4 ton long box gas (different roads) truck. And with a 1/2 ton long bed gas truck (yet different roads). With a properly loaded trailer with just under 500 lbs tongue weight. It's when the seams are just at the right locations for the vehicle plus the trailer. Different vehicles and trailers will do it on different roads. Changing your speed helps. So does learning what roads to avoid (that's what I do). Of coure you have to relearn every time you get a different tow vehicle or truck.

Some tow vehicles are a lot more prone to this than others. There's no real easy way to figure out when it will do it, other than to try different roads.