Scary times as trailer sways violently on downhill grade

Dear Eric, I pull a 19 foot Airstream “Bambi” with a long bed Dodge 4X4 diesel truck. Storage is very limited in the trailer and I wanted to make some extra room. So I put a 60″X20″ cargo carrier on the back of the trailer. On my RV last trip I had my generator and some firewood on the back carrier, estimated weight of all at less than 150 pounds. I had no problems with the trailer performance for the first 250 miles but when we got to the summit on Interstate 80 and started downhill toward Reno I experienced a hair raising ordeal. I was traveling at 60 mph and just activated my exhaust brake to get back to the speed limit when the trailer began a violent sway from side to side. I knew that normally you should accelerate to pull out of this condition, however I was going downhill and that would have complicated the situation. I knew if I hit the brakes it would have made the situation worse. I thought about using the manual electric trailer brake but wasn’t sure it that was wise, either. I had to move into the center of the two lane highway and ride out the swaying as I let the unit slow down gradually. It took about 3-5 miles and was very scary. I think the problem is that I must have changed the tongue weight on the trailer with the carrier on the back. If so, is there a way I can make the trailer operate safely again without removing the back carrier? Or am I wrong and have a more serious problem and must remove the carrier? – Jeff Locke

Dear Jeff, Adding the weight of the storage box to the rear of your trailer must have been enought to unload the tongue weight on the trailer. I see this a lot on trailers and motorhomes when additional weight is added to the rear of the unit. The additional weight will unload the front and make it handle poorly. You did not say if you were using a sway control unit with the hitch. If not, that would have helped a lot. But you should probably give up the storage unit on the rear. As for getting out of the situation that you were in with the out-of-control swaying, you might have been able to stop it by manually applying the trailer brakes without the truck brakes. That would have put all the braking in the rear on and would have straightend out the tail waging the dog. Doing so, it would not take too long for the trailer brakes to get hot, but it most likely would have done the trick.