How to control or eliminate trailer sway?

Trailer sway is not only frightening for RVers, but if not controlled can cause an accident. But is there anything you can do to prevent or at least minimize trailer sway?

The first step is understanding the causes of trailer sway, or fishtailing. Weight distribution is a primary factor: You need at least 10-percent of your trailer’s total weight “on the hitch.” With a properly designed trailer, weight distribution is up to you. If you have a lot of personal stuff in your trailer, put the heavier stuff forward of the axles.

Another cause of sway is a bad match-up between tow vehicle and trailer. Exceeding a tow vehicle’s capacity will often lead to problems. Some RVers will match their trailer and tow vehicle based on the unloaded weight of the trailer, but then fill the holding tanks and stuff the trailer full of cargo and merrily head off down the road, by then exceeding the tow rig’s ability to pull safely.

Factors encountered on the road make up the balance of most sway issues. Wind gusts blasting the trailer, “bow waves” or winds pushing onto the trailer/tow combination by big trucks, steep downgrades, and vehicle speed all can cause sway problems.

The most common sway control is a friction sway control that links your tow vehicle to the trailer and reduces that nasty pivoting between trailer and tow rig. These units are inexpensive – we’ve seen them for less than $50 up to a little under $200, and you may be able to do the installation yourself.

Wind gusts and blasts from trucks passing your rig are often unpredictable and can catch you off-guard. If you’re hit and your trailer begins to sway, RESIST the temptation to jump on the brake pedal – this will often make things worse. Gradually reduce speed by backing off on the throttle. If the sway is severe or doesn’t respond, use the manual lever on your brake controller and gradually apply trailer brake power to let the trailer do the braking and eliminate the sway.

Your speed can create sway problems. “Keep it down to a dull roar” should be common sense. If you find your combination swaying, ease off the throttle, get back into control. If you find a repeat of the problem as you speed up, then your speed is too fast for conditions. Be especially wary on downgrades and keep your speed down. Being on a downgrade, swaying, and trying to slow down all at the same time can be a real hair-raiser.