Yaw, more commonly known as sway in the RV industry, is a dirty word for trailer owners. The definition of yaw or roll is a movement from side to side. Nothing will ruin the way you feel about camping faster than the first time you experience trailer sway.
You’ve been camping in a tent for years and now you decide it’s time to move to a pop-up. You go to your local dealership and find a pop-up window with the perfect floor plan for you and your family. The seller knows that he will be close to the maximum weight his vehicle can tow. It really needs a sale because things have been slow. Rather than risk losing the sale, he decides not to explain the added expense of proper hitch work to safely tow his new trailer.
You are ready for a weekend getaway. He’s done all the pre-trip checks and is ready to go. You load the most precious cargo you have, your family, into your tow vehicle and head out on a new adventure. Everything is fine when you leave home. You take the ramp to the interstate. You are driving at the speed limit enjoying the music on the radio. Suddenly, out of nowhere, a transfer truck going twenty miles over the speed limit passes you as if you were standing still. The popup is inserted into the draft created by the truck. In an attempt to correct this totally unexpected event, you oversteer and the trailer starts going in the opposite direction. Not sure what to do, he hits the brakes and turns the wheel to the left and then to the right. Now that one-ton trailer behind your SUV is yanking from side to side and starting to affect what little control you have over the vehicle. The results are catastrophic.
Ok, since this is just an article, let’s start over and fix this before you even realize there’s a potential problem. She purchased her popup from a reputable local RV dealer. At the risk of losing the sale, your salesman explains that he will need specialized hitch work to pull his new trailer safely. You are a bit skeptical, you feel like they just want more of your money. Besides, your father never needed any of this. He just hitched the trailer to the ball and off he went.
He decides to give the salesperson the benefit of the doubt and listen for a minute. He shows her in his book that his tow vehicle is rated to tow a maximum of 3,500 pounds. He then explains what he should consider for that tow rating. It includes the weight of your new motorhome, all aftermarket accessories such as roof-mounted air conditioning and battery to be installed by the dealer, all cargo and personal belongings you load in the trailer and tow vehicle, and the weight of the passengers in the vehicle. Now, all of a sudden, the salesman has his full attention. You had no idea that all of this had to be considered.
He shows her the weight tag on his new trailer. Unloaded Vehicle Weight (UVW) is 2,100 lbs. The air conditioner weighs 100 pounds and the deep cycle battery weighs 50 pounds. To be on the safe side, he estimates that he will carry about 300 pounds of cargo and then adds another 300 pounds for his wife and his two children. He surprises you how quickly things add up.
You now have 2,850 pounds instead of the 2,100 pounds you thought you were. It is not over yet. Your salesperson begins by explaining that each state has different requirements for how much a trailer can weigh before it requires trailer brakes. In your state, the weight is 3,000 pounds, but your dealer has brakes installed on any trailer you order that weighs more than 2,000 pounds. He explains that even though his vehicle is rated to tow 3,500 pounds, the vehicle’s brakes were designed to safely stop the weight of the vehicle, not pull an additional ton and a half behind it.
He takes him to the parts department and shows him a brake controller and explains that this is what activates the trailer brakes and that the dealer will install it when he wires the trailer lights. He likes the features that he explained about the brake controller. The fact that he can manually adjust the amount of braking action so that when he hits the brake pedal, the tow vehicle and trailer work together to stop the weight in a reasonable amount of time. What he really likes is the part he explained about the manual override lever that activates the trailer brakes without using the vehicle brakes.
He said if you’re on a steep grade and you don’t want to prematurely wear out the vehicle’s brakes, slowly slide the lever and the trailer brakes will slow you down. But what he really sold on was when he explained that if the trailer starts to sway, you can gently move the lever, activating the trailer brakes, to help straighten the trailer. He went on to explain that trailer sway is one of the biggest potential problems you can encounter when towing a trailer. He points out some of the factors that contribute to trailer sway.
o First and foremost, poor trailer design contributes to trailer sway. When there is too much weight behind the trailer axles, causing the tongue weight to be less than 10% of the trailer weight, it has a natural tendency to sway.
o Incorrect tire inflation
o Improper weight distribution hitch adjustments
o No trailer sway control
o A transfer truck passing from the rear of the trailer.
o Descending slopes
o Towing speeds
o Tow vehicle is not properly matched to trailer
o Improper load, overload and poor weight distribution
He took the time to explain that for the trailer to pull properly, the manufacturer recommends that the weight of the tongue resting on the ball mount be 10-15% of the total weight of the trailer. He said if it’s more than 15% they have what’s called a weight distribution hitch that takes the extra weight off the tongue and distributes it to the axles of the tow vehicle and trailer where it should be, and if it’s less than 10% when you carry your load, it spreads it out to add some extra weight on the tongue. He looked up the popup you were buying in the brochure and the tab weight was 305 pounds. With the air conditioning installed and your load loaded, it would be between 10 and 15%. He explained that a weight distribution hitch was more commonly used with heavier trailers and in some cases with pop-ups depending on the towing vehicle, but in this case it would not be necessary.
The next thing he asked was if his vehicle had a receiver. You reply, do you mean a hitch? He explains that the part that is bolted to the vehicle is called a receiver and shows you a chart that has several different kinds of receivers depending on the amount of weight it will be towing. The Class II receiver was rated for 3,500 lbs. gross trailer weight and 300 lbs. Maximum weight of the tongue. For a small price difference, he recommended a Class III receiver rated for 5,000 lbs. gross trailer weight and 500 lbs. maximum tongue weight as your trailer tongue weight exceeded 300 lbs.
With that done, he said, let me show you the one component our dealership highly recommends to anyone buying a popup. She reached over and picked up a part of the shelf. This is called friction roll control. We mount one end to the ball mount and the other end to the lug on the camper. Adjust the amount of friction by turning the lever clockwise for more friction and counterclockwise for less friction. He explained that you should turn it in 1/8″ increments until you get it where you feel comfortable. This won’t totally eliminate the sway, but once the sway forces are in motion, it will dampen the sway and help you control it when you’re towing. your caravan
Well, he said, that’s all. For less than 10% of the pop-up price, you can do all the snagging work and make sure your family is safe when you go on the road. At this point, he is convinced that the seller has his best interests in mind and was not just trying to make more money.
You are ready for the first weekend getaway with your new popup. He performs all the pre-trip checks that the dealer explained to him and he is ready to go. You load the most precious cargo you have, your family, in your vehicle and head out on a new adventure. You take the ramp to the interstate. You are cruising at the speed limit enjoying the music on the radio. Suddenly, out of nowhere, a transfer truck going twenty miles over the speed limit passes you as if you were standing still. You feel a slight movement behind you. It was enough to remind you that you are pulling the popup. You look at your watch and tell the family that you should be at camp in a couple of hours.
Knowing how to react when a trailer begins to sway can be the difference between your safety and disaster.
Copyright 2006 by Mark J. Polk owner of RV Education 101