What makes a trailer start to sway?

[Tinkerer]

Ain't happened to me and I don't want it to, but I'm curious. <br /><br />Obviously it's probably not set up right in the first place, but there are people who've towed the same rig on the same car for a considerable distance or on earlier trips with no problems.<br /><br />Then she starts to sway and then if it gets out of control it's curtains. This suggests that there's some combination of factors that starts the sway.<br /><br />What's the best way to deal with it if it starts to sway? I've heard of people accelerating but then just crashing at a higher speed, where a mate of mine did it and regained control. Probably wouldn't work in my manual transmission car because I'd probably be in overdrive and have to change down a couple of gears to get any real acceleration, and the change in the car's speed and attitude on changing gears would be the same as light braking for a few seconds.<br /><br />Anyone actually dealt with it on the road?

 

[Dunaruna]

Re: What makes a trailer start to sway?

I can pick the time that you knock off work tink, it's about the same time I sit down and start my end of day invoicing.<br /><br />Lots of things can affect the way a trailer tracks, tyres, brakes, suspension but the big three are tongue weight, tracking true (not crabbing) and the weight relationship between the vehicle and the trailer. <br /><br />You are probably going to get replies quoting all sorts of equations and percentages but in my humble opinion it comes down to one thing when the trailer begins to do the hookie pookie - if the trailer is heavier than the tow vehicle you are in for a ride of your life. If she starts to sway, accelerating is the best way to ATTEMPT to pull the trailer out of the sway, jumping out the door is also a viable option .<br /><br />Aldo

 

[AK_Chappy]

Re: What makes a trailer start to sway?

I had a full load once, two ATV's, meat trailer already loaded and an ATV in the bed. We were on an 8 hour drive to reach our hunting camp trailhead. On the way through the mountains, I could not maintain speed. The trailer would start to sway BAD. I could feel it trying to break the back of the truck loose. I tried braking and that made it worse. Acceleration would straighten the trailer out and then I could immediately brake and keep it under control. We were only about an hour from the next town and no street lights to speak of, pullovers or anything so we pressed on. Stopped for gas and found out that one of the straps had rubbed and broke. One ATV on the trailer was about a foot further forward than where it started. We pushed it back and put on a new strap. Trailer handled great from then on.<br /><br />Long story to say - too much tongue weight. Not enough tongue weight will also cause it. Seems to be associated with higher speeds also. It has always been my experience that a good hard steady acceleration straightens it out. You can then brake while it is still straightened out and slow down to where the trailer doesn't sway. This will get you to the next stop to readjust trailer weight.<br /><br />AK Chappy

 

[all thumbs]

Re: What makes a trailer start to sway?

If you have trailer brakes where you can just hit the lever for those [not using your vehicle brakes]that will stop the sway.

 

[jtexas]

Re: What makes a trailer start to sway?

what makes a trailer sway? too many beers, not enough sleep, talking on the phone, trying to read a map, strong crosswind, misaligned wheels, avoiding potholes, not avoiding potholes, blowout, bad luck, uneven pavement, worn springs, unequal tire pressure, bikini babe on the side of the road, armadillo in your lane, jerk cutting it too close, worn shocks, unbalanced load, teenagers, democrats, lawyers, failing to brush & floss regularly, inadequate roughage in the diet...wait, think I went too far there...sorry...

 

[imstillatwork]

Re: What makes a trailer start to sway?

Bwahhh-haaaa...

 

[jtexas]

Re: What makes a trailer start to sway?

did I mention eating a cheeseburger, smoking a joint, girlfriend sitting too close, "hey Dad look at this", mother-in-law won't shut up...

 

[noelm]

Re: What makes a trailer start to sway?

HI<br /> done a lot of towing and without a doubt the biggest cause of trailer sway is too little weight in the tow ball/car, this is especially bad on a single axle trailer, as the added weight in the rear of the boat/caravan whatever it is, acts like a large pendulum and once it starts it can prove to be rather "exciting" best practice to have the correct weight on the tow vehicle tow bar (which can vary according to vehicle and trailer weight) and travel at a speed that is safe for the conditions and the setup in tow.

 

[noelm]

Re: What makes a trailer start to sway?

ooops sorry, the post should say too little weight ON the tow ball

 

[jimmbo]

Re: What makes a trailer start to sway?

If you're putting so much weight on the towing vehicle hitch that it starts to make the front end light and skitish you really need a weight distribution hitch.

 

[trebot]

Re: What makes a trailer start to sway?

TOO LITTLE WEGHT ON TRAILER TONGUE IS USUALLY CAUSE OF TRAILER SWAY.<br /> As a general rule, you should have 8% to 10% of the trailer total weight on the tow vehicle hitch.<br /> Take boat on trailer to a weigh scale. Truck stops or moving companies have them. 1) Drop the boat/trailer on the scale & weigh only the boat/trailer. 2) Hook-up to tow vehicle and weigh again with ONLY trailer tires on scale. 3)Subtract weight 1 from weight 2. This is your tongue wight. Calculate what percentage of total weight this is.<br /> To increase tongue weight, move boat forward on trailer OR move axle(s) back .<br /> Ain't easy, but a smooth tow is worth the effort.

 

[roscoe]

Re: What makes a trailer start to sway?

Had a real bad experience towing a camper with a 1970 Olds Delta 88 Land Yacht. It always behaved very well until one day on a long trip when we started down a very steep hill. Couldn't hit the brakes to slow down as this increased the sway to the violent level. We just cinched up the belts and let her run that hill. Hit the bottom at 100 on the speedometer and crossed a very very narrow two lane bridge at the same time a tractor trailer was crossing the other direction.<br /><br />Knees were shakin and sweat was rolling, miraculously the pants stayed dry. Lessons learned that day.

 

[notinbig]

Re: What makes a trailer start to sway?

Towed trailers all over the country never had a sway problem. I take along time to load and make sure it is even though-out the trailer or boat or car whatever your towing.

 

[Johnshan1]

Re: What makes a trailer start to sway?

My buddy always has issues with swaying trailers, he never has enough tounge weight, but he has not taken my advice yet, he has ruined 2 tounges to the point where the attachment bolt point breaks, some people just know everything.

 

[Bondo]

Re: What makes a trailer start to sway?

What makes a trailer start to sway?

An Imbalanced Load .....<br />Or, Possibly a Mechanical Issue.........(Alignment)

 

[chrisg]

Re: What makes a trailer start to sway?

I saw a sight on I-80 at the bottom of a hill. Someone's vacation was ruined!. It looked like a new pick-up and 5-wheeler park model ( big) on their sides!!<br /><br />I felt bad for the guy, as I drove past, he was having a tong lashing from the She-boss as they stood at the side of the highway. At least he just got passed the river, otherwise the new toys would have become submarines!

 

[Silvertip]

Re: What makes a trailer start to sway?

CanadianInIowa -- I drive I-80 frequently from Des Moine enroute to Denver and there are several hills and valleys in Iowa where cross-winds catch people by surprise. I can't remember one trip where I didn't see a camper or boat in the ditch. Bet those folks also had a bit of sway before being caught by the wind.

 

[rwidman]

Re: What makes a trailer start to sway?

Tongue weight needs to be correct. For boat trailers, it should be between 5% and 7% of the weight of the trailer with the boat and fuel, etc. with tandem axle trailers at the low end of the range. The trailer should be level with the pavement when connected to the tow vehicle.<br /><br />Cross winds can have an effect as can passing vehicles, especially large trucks moving at a speed greater than yours.<br /><br />To avoid these conditions, be aware of your surroundings, check your mirrors for approaching vehicles, and slow down when appropriate. Don't make any sudden changes to speed or direction. If you suspect a problem, let off the gas and slow down gently. Don't apply the brakes, it will make the sway worse.<br /><br />trebot's method for measuring tongue weight is correct but it's important to have the boat positioned correctly on the trailer (transom supported, etc.). Once this is done, move the axle(s) to get the correct tongue weight.

 

[BoLin]

Re: What makes a trailer start to sway?

We just brought home (to MD) a boat (20 ft Grady) that we purchased used in NJ. We did fine except whe a semi or especially a bus passed us. The sway was very scary, but we just eased up on the accelerator and were able to get through each episode.<br />If the sway only occurs with passing buses, should we make any of the adjustments mentioned above or are they not going to make a difference?

 

[QC]

Re: What makes a trailer start to sway?

My experience with the bus/truck thing is that the big wave of air off the front of the bus/truck blows on four different pieces of the vehicle combo and causes that wiggle. First, if they are pasing you, their air hits the stern of the boat causing the bow to move the opposite direction, then the air hits the bow section, pushing the other way and continues pushing that way on the back of the tow vehicle, finally it hits the truck/car in front of the rear wheels pushing the opposite direction again.<br /><br />If it settles down immediately after the offending vehicle passes you, and behaves well under all other circumstances, then I am not sure you can do much about that except go faster . . . i.e. don't let 'em pass you.