Tongue Weights

[honda03842]

The following is a picture of our set up for weighing the trailer that I described earlier in the thread.

I think there are a number of factors that contribute to sway such as trailer tire pressure, distance to the tow vehicle's rear axle, tow vehicle tire pressure, weight distribution in the trailer and tongue weight.

All recommendations in publications in the United States refer to 10-15% tongue weight number. This, 10-15%, would be considered on the high side in Europe.

As you can calculate, we are typically in the 8% tongue range. We have never experienced sway.

Though no one wants sway and every effort should be made to set up your trailer to prevent sway, applying 'just' the trailer brakes can stop sway before it gets out of control. I think this is another reason to have trailer brakes.

I know most worry about sway, but the biggest cause of trailer accidents seems to be the trailer coming off the ball, an easy situation to prevent. Now after locking the ball, we use to the trailer's front jack to try and jack the receiver off the ball, a quick test.

[steve dunham]

Originally Posted by cpaharley2008

In other words the waste is completely removed but you leave some residual liquid.

Yes ,about 1/2 to 1 gallon of clean water plus a couple of ounces of Pinesol . I left the tank almost full one time and found I couldn't shift or lift the tongue by hand , but I can when the tank has only a little water and Pinesol.
in it. I did read that when your hooked to a sewer you should not leave the valve open all the time because the solids build up. I think you and and I are doing the same thing only expressed differently.
Thanks Jim
Steve D

[Andrew Gibbens]

The scientific evidence, whilst in fairly short supply, says that a certain tongue weight percentage on its own is not necessarily enough for safety - the distribution of weight must also be sensible.

In particular, a trailer loaded with heavy weights on the front and back will be much less stable than the same trailer loaded to the same tongue weight with the heavy weights in the middle near the axle.

I've posted a link to this European study before but it is so well presented that it bears repeating: Caravan Stability Study

The 'Stability Studies Game' may be called a game, but is actually a proper simulation program in which you can alter the loading and tow speed to see what effect it has. I think everyone can learn from this - and they don't have to risk rolling their trailer over to do so.

[honda03842]

Andrew,
Thanks for posting the Stability Study. Well worth reading with clear suggestions: keep the weight over the axle, drive at reasonable speeds, and even a mention of 7% tongue weight.

Bailey Caravans has a competition each year, 2011 was their 28th year, forbest tow vehicle of the year. Very impressive. You can see the results at the top of the page of the Stability Study.

Thanks

[honda03842]

The neatest aspect of Andrew's post is the fact that here's a trailer company that actually tests and publishes the results of towing their trailer's with various tow vehicles, openly providing information.

This is smart and impressive. The only other company I know that does this is Can-Am RV.

[Donna D.]

Originally Posted by wklose99

Is sway a result of tongue weight or is sway a result of the angle at which it connects to your ball?

You missed Jim's answer:

Originally Posted by cpaharley2008

Both, too light and the tail starts wagging and if not level more chance of sway, if both exists, then it becomes un towable.

[floyd]

Each of these Escapes has done well towing with a 29 battery, a full propane tank and two Trek 820s on the tongue of our Scamp13D front bath.

[honda03842]

Floyd,

What is your tongue weight with bikes?

Thank you

[Carol H]

[QUOTE=honda03842;328392]
As you can calculate, we are typically in the 8% tongue range. We have never experienced sway.
/QUOTE]

hummm correct me if I am wrong Norm but I could have sworn that you have an anti sway bar on your hitch. I would be really worried if it was to manage to sway with one of those on it.

[honda03842]

Hi Carol,

I know you can get sway even with an anti-sway bar. No one should ever think that because they've added an anti-sway bar that they're free of a sway situation.

Every day when I start up in the morning I reach for the brake controller's trailer brake activiation switch and activate the trailer's brakes to test them and to reinforce that should I get sway, that I can stop it by activating the trailer's brakes.

I do have an anti-sway bar on the Scamp 16 however I've towed our Scamp 16 about 2000 miles without an anti-sway bar and towed a Casita 16 about 4000 miles without an anti-sway bar. In both cases I have never seen sway and in both cases I had well less than a 10% tongue weight.

As to the anti-sway bar, before we ever towed I investigated whether I should purchase an anti-sway bar. The reponse was you'll probably never need it but in an emergency it's nice to have. Since it was only about $50 and easy to install I bought one.

We have had two emergencies, neither related to sway. I've published the second on this site where our trailer's receiver hopped off the ball due to a receiver modification by a previous owner. In that case the anti-sway bar held it all together.

The first situation was a full bore emergency stop, the worst of my life, where an extend cab truck pulled across the highway blocking both lanes forcing an emergency stop from 55 mph, smoking tires and all. The trailer stayed perfectly in line with the Honda. Did the anti-sway bar do anything in this situation? I don't know but I was glad every thing stayed together as it should.

It's quite clear that the Scamp tracks very well. It has never moved from side to side at all with or without the anti-sway bar. I make no secret of the existance of the bar and have mentioned it many times on the site.

I will also say that load distribution is important. We had an earlier non-fiberglass trailer where we mounted a small generator on the rear bumper. We had an anti-sway bar on that trailer, yet it swayed in the first 10 miles, enough so I stopped and pulled over and moved the generator inside. Obviously balance matters with or without an anti-sway bar. I think part of the Bailey testing mentioned in an earlier post shows that weight distribution is important.

When someones sends me a PM asking about towing with our CRV, I send them a 3 page document where I state we tow with an anti-sway bar and as well that we've towed without an anti-sway bar. I try to take this subject seriously and be totally open because some people are suspicious of our Honda CRV and our towing methods. After 5 years of towing all over the continent with our Honda CRV I am very happy with the results and more than willing to share what we've learned, just PM me if you want a copy.

I considered posting this document on Towing with a Honda CRV on the site but have refrained because too many people get their dander up over our towing style. Some are concerned about our potential liability, some think I'm a danger to others.

The reality is that we're very careful and conservative people, checking and rechecking our tow vehicle and trailer almost daily. We've even gone so far as to install pressure sensors on our tires to know what the tires are doing. We're careful but more importantly our Honda has done the job without a single drive line repair in 8 years, 5 years of extensive towing. We're now into our 284th day on the road this year. No one has tooted at us because we're too slow or too fast, even on the many long and high passes we've crossed. We're happy with our Honda. We only wish Honda's marketing department would give us the same ratings they give the Europeans. More so we wish they would import their 4 cylinder diesel. Then we could do well better than 23 mpg.

Safe Travels,

[Carol H]

Sorry Norm you seem to have gotten side tracked. I wasn't questioning your choose of car or trailer combo. This thread is in regards to tongue weights as was my question.

The reason for my question was I felt the OP who may be new to towing should know that IMHO a very important piece of information was missing from your post in regards to your practise of towing with a 8% tongue weight. As you went to the expense of purchasing and installing a sway bar you obviously felt it was a worth while investment with your set up. Its a piece of equipment that I think you will agree will have a pretty big impact on how frequently or infrequent you find yourself with a sway with such a light tongue weight.

As you know I tow the same make and model and vintage trailer as yourself & actually manged to towed 12,000 miles last year without a sway bar and without any sway issues. But I know very well that under certain circumstances I could very easily get my trailer to sway especially with an 8% tongue weight. Bottom line is sending someone out who is new to towing with an 8% tongue weight IMHO its a recipe for a disaster, especially when one considers the party may not know under what circumstances a sway is likely to occur or even know what to do or not do if the trailer does start to sway

As indicated its just MHO.

[cpaharley2008]

I believe Norm's trailer came equipped with the sway from prior owner and Norm utilizes it. Whether or not he has some sway can not be determined. But proper weight on the tongue should help alleviate sway. Thus any newcomer should be aware of following the trailer manufacturer's recommendations. I think it is better to have the trailer handle sway in lieu of the sway control constantly fighting to keep things straight. I have seen dual sway setups and I wonder why someone would want to tow knowing the unit had an issue with swaying so much. I once owned a trailer for less than 6 months because of it's horrible sway which I could not alleviate no matter what I did.

[Bob Miller]

In my experience, sway is a result of inadequate tongue weight and the "Tail wags the dog". Years ago a friend of mine somehow thought that less tongue weight was better and loaded up the back of an 18' ski boat on a trailer to almost zero out tongue weight, a really bad idea.
He hit his brakes going down a steep grade on I-90 in WA and the trailer started whipping around and, before he thought to accelerate or try manual trailer brakes to stop things, they were off the road and the trailer was on it's side, having twisted the entire front part of the frame into a pretzel and the boat was damaged beyond repair. Fortunately no injuries, but lots of pants needed changing.

That said, I carry a $5 flea market scale and try to stick with about 15% tongue weight, it do make a difference.

[Thomas G.]

For engineers and wonks, I found this excellent analysis of tongue weight and trailer sway on another forum. See postings by Ron Gratz

Don't ask me to explain it.



RV.Net Open Roads Forum: Travel Trailers: Towing stability physics

[honda03842]

1. I've towed 3 trailers, a 15.5 foot stick built Sunline, a 16 foot Casita and a 16 foot Scamp.

2, Each trailer had tongue weights in the 8-9% range. My intention is to keep the tongue weight at or below 220 lbs, the Honda's limit.

3. None of these trailers had anti-sway bars when purchased.

4. Initially I towed all these trailers without anti-sway bars. The Casita and Scamp were towed for 1,000s of miles without anti-sway bars. Sway was never experienced.

5. I installed an anti-sway bar on the Sunline. It swayed once with the anti-sway bar in place when I put a small generator on the rear bumper. The anti-sway bar did not stop the sway; I stopped it by hitting the trailer brakes (note not the Honda's brakes) and eleminated the sway by moving the generator to over the trailer axle.

6. I added a anti-sway bar to both the Sunline and Scamp, not to prevent sway though I'm sure it would help with sway, but rather for emergencies. The Casita was never towed with an anti-sway bar.

6. My opinion after 2 non-sway emergencies is that an anti-sway bar is very inexpensive insurance.

7. I am not suggesting what others should do but rather stating what works for me. Simply sharing information.

The only thing that bothers me about 10 to 15% is that people state it but never seem to be able to explain why it's necessary.

[Bob Miller]

I don't think that the physics of the question are as important as the results.
As Norm pointed out, placing a generator on the back of his trailer (thus reducing tongue weight or, more correctly, front to rear trailer balance) contributed to sway, and moving it forward fixed the problem. Again, the tail wags the dog.
Not mentioned is the probabilty that vehicles with front wheel drive may be more prone to sway issues simply because the point of "pull" is further away from the pivoting center of the trailer, as well as FWD vehicles have a higher ratio of vehicle weight on the front wheels and less on the back.
I know when I pull either of our trailers with our 4 cylinder Sonoma pick-up rather than with our 2009 Honda CRV, it seems that the trailer has less control over tow vehicle.

[Thomas G.]

Originally Posted by Bob Miller

I don't think that the physics of the question are as important as the results.
...........

I have a hunch that the two are not separable.

[Bob Miller]

What with all of the formulae offered in the link explaining trailer sway, maybe I should have said:
"I don't think that "understanding" the physics of the question are as important as the results. "
If I drop a bowling ball on my foot, I don't need to know why it hurts more than a tennis ball.

[Thomas G.]

Originally Posted by Bob Miller

What with all of the formulae offered in the link explaining trailer sway, maybe I should have said:
"I don't think that "understanding" the physics of the question are as important as the results. "
If I drop a bowling ball on my foot, I don't need to know why it hurts more than a tennis ball.

I'm not sure. Could you post a video of you dropping a bowling ball on your foot?

But seriously, getting the "it isn't the tongue weight, it is the lateral forces due to angular momentum of the trailer" part keeps you from adding large weights to the ends of the trailer.

[Bob Miller]

Want's Pain Pics?
Actually I had to give up bowling from frustration after blowing my very first 300 game, (in the second frame). After that it was all down hill.....

And... It's the trailers transrotational nexxus value, when added to the angle of the hitch dangle, divided by the current phase of the moon that determines actual sway pressure when measured as inverse momograms. Needless to say, this makes it much safer to drive in a full moon when the pressure value will be the inverse of 1.