Sway Control

Equalizer bars, anti-sway control, weight distribution hitch, spring bars … even if you are a seasoned Airstreamer you might think you know the difference, but it’s easy to be confused because the industry uses these terms interchangeably. And after seeing a viral video recently circulating online—footage of a trailer alarmingly fishtailing on the freeway—you may be downright apprehensive.

“Many new Airstream owners don’t know if they need sway bars, or how to use them,” said David Montijo, Airstream Sales Consultant at Lazydays RV in Tucson, Arizona. Are you doing it wrong when it comes to sway control? Answers below.

What’s the difference between all these terms?

Sway controls and weight distribution “have two completely different functions,” said Montijo. Confusion reigns because sway control systems are integrated into many popular weight distributing hitches. That means the long black weight distribution bars on your Equal-i-zer, Reese Dual-Cam and many other hitches fill a dual role: distributing weight from the trailer’s tongue to the front wheels of the tow vehicle AND limiting sway. These systems rely on friction to discourage rapid movement of the trailer, which helps prevent sway.

More sophisticated “sway prevention” hitches such as Hensley and Pro-Pride prevent sway inherently as a result of their internal geometry, so on those hitches the weight distribution bars are just doing one job.

But some other hitches don’t have integrated sway control at all, and some people tow just by putting the trailer on the ball without any additional hitch system. For those people, an add-on friction sway control is a very good idea.

What causes sway?

A myriad of conditions can allow your any trailer to erratically—and dangerously—fishtail, including: crosswinds (including the blow-by gust created by passing semi trucks and other high-profile vehicles); improper loading (too much weight at the back of trailer); or too much (or too little) tension on the sway bars.

Do I even need sway control?

It’s a good idea. “Sway bars are not required, but are necessary in case of crosswind, or when trucks are passing the unit,” said Montijo. The problem is that you can’t just slap on a sway control the moment you need it. So advance preparation is the best strategy, kind of like wearing a seat belt.

Most dealers will recommend standard weight-distribution hitch that includes sway control, so check that the one you’re using has that feature, and that it is adjusted correctly.

If you don’t have such a hitch, an independent friction sway control can be added. A typical design has a bar mechanism that moves freely as your trailer turns normally, but applies friction to create resistance—similar to the way shock absorbers reduce bounce—if your trailer begins an unwelcome swaying movement.

I have a small Bambi—but it was built in the 1960s. Do I need to worry about sway control and weight distribution?

The need for weight distribution depends on the tongue weight of the trailer. Short and light trailers from the 1950s and early 1960s often have tongue weights below 300 pounds. Weight distribution will have a minimal positive impact with such light loads, especially if the weight distribution hitch itself adds 50 or more pounds.

But that doesn’t negate the possibility of sway. “All trailers, vintage as well as new models, can and should use some type of anti-sway control for added safety,” said Montijo. Sway control helps with side winds and also when you’re towing down a steep, winding hill, and going over bumps or around corners.

Uh oh. I’m swaying on the road. What do I do?

Don’t panic. “Manually apply the brake to the towable by using the manual switch on the brake controller in the cab of the tow vehicle,” advised Montijo. “When it’s safe to pull over, adjust the tension on the anti-sway bars.”

When the trailer is swaying, it’s because it has more kinetic energy than the tow vehicle. In other words, it is no longer under the control of the tow vehicle—and this can happen regardless of the size or weight of the tow vehicle. The trailer responds by using up that energy by swaying from side to side.

One incident of sway is a warning: something is wrong. If you don’t correct the cause, it will probably happen again. So think about why the sway started. Is there a mechanical problem with the trailer? Is the tongue too light? Heavy winds? Get professional advice before you tow again.

Sway bar tips

(These tips apply to independent sway controls, not those that are integrated into weight distributing hitches.)

You’ll know when an independent sway control is too tight: it’ll squeak. If it’s too loose, fishtailing or swaying can occur. “Each name brand has a different adjustment,” said Montijo. “For proper adjustment it’s best to refer to the owner manual.”

Remove your friction-style sway bars before backing into your campsite. Reversing will be easier (and you won’t damage the tension system).

Avoid towing on icy roads, but if you must, loosen the tension when towing on icy roads. Otherwise the sway control might force the trailer to track badly behind the tow vehicle, making things worse.