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turbojimmy's avatar
turbojimmy
Explorer
Nov 16, 2015

Trailer Sway - non RV question

I rented a U-Haul trailer to tow our latest project back to NJ from SC. I've used these trailers several times in the past without any issues, with the same tow vehicle (my '07 Avalanche) and cars that are a similar weight.

This trip was about 700-miles each way. So you could imagine my panic when I loaded up and got on the highway and the thing was swaying all over the place. I was not looking forward to a white-knuckle, 14-hour ride home. I made it, but I'm looking for some insight to avoid this in the future.

Max towing capacity is 8,000 lbs. on the Avalanche. U-Haul trailer weighs 2,200 lbs. The car's (1964 Impala wagon) "shipping weight" is 3,900 lbs. That's 6,100 lbs. total. The wheelbase of the car was pretty much as long as the trailer, with a significant amount of overhang out over the back of the trailer (I'd say 3-4 feet). I'm thinking this might have been part of the problem.

Upon accelerating onto the highway the first time, it started swaying at around 55 MPH. It got worse and worse so I let up on the gas (did not apply brakes) and let it coast until it was under control. I slowly accelerated to 50 MPH where it seemed okay. On the flats and uphill it seemed okay, but going downhill it would start to sway pretty bad above 55 MPH. I got off on the next exit.

I remembered reading here (I think) that increasing the tongue weight can help. I took the spare out of the back of the wagon (even though it only weighs like 50 lbs) and put it in my truck. Even though the trailer and truck were level (I have a drop hitch), I pulled the fuse for the auto-level suspension and let it drop a bit hoping for more weight on the tongue. That seemed to help a lot, but it was still pretty sketchy.

My dad commented that the tongue on the trailer seemed to be unusually long - and it was. It had the trailer probably 4-5 feet behind the truck. Not sure if that's a factor or not.

We stopped for the night after about 8 hours. My nerves were frayed.

For the last leg of the trip, I tightened up the surge brake on the trailer so that it would engage earlier. I made sure it was still free at a stop. This seemed to make a huge difference - the rest of the ride home was pretty good. Going down hills the surge brake would seem to kick in and keep the sway under control, or if I braked slightly the surge brake would immediately correct the sway (I know you're not supposed to brake). Trucks passing would upset it a bit, but that's to be expected.

Any guesses as to what the issue was here? I know it's not a lot go to on, but it's really shaken my confidence in towing with these trailers.

18 Replies

  • Thanks all. Here are a couple of pics:





    See how long the tongue is? Is that a factor. You can see the overhang, too. I was happy to get everything and everyone home in one piece!
  • donkeydew wrote:
    was the car all the way forward on the trailer? sound like not enough tongue weight and to much overhang on the rear taking weight off the hitch.
    Like others have said not enough tongue weight.
  • Ivylog's avatar
    Ivylog
    Explorer III
    I have a tilting car trailer that wants to sway, even empty. It has torque flex axles (non equalizing) and I' ve learned to use a raised ball (trailer higher in the front) so more weight is on the rear axle which results in more tongue weight and no sway. Have to do the same on a 31' Airstream with torque flex axles. I've thought about lowering the rear axle 1/2" so I can keep it lever.
  • Yes, it was the overhang.............in a round about way.

    Hears the deal. When a car is very long and the trailer is short a lot of weight can go behind the trailer axle. Not a good deal. Just like a fat kid on the end of a teeter totter the rear end of the car will take tongue weight off of the front of the trailer.

    You did good by putting the spare up front. Very smart move. Even a few lbs can make a difference.

    I towed a trailer with 0 tongue weight this last weekend. Only had to go about 2 miles at no more than 40 MPH. It was only about 1,500 lbs but it wanted to take my diesel off of the road and put it into a ditch.
  • Thanks both!

    Yes, the car was all the way up to the wheel stops on the trailer. I'm starting to think it might have been the overhang, too. There was no way to reposition the car, unfortunately. The last car I towed was a more modern version of that Impala - a '96 Roadmaster Wagon. It was about 500 lbs heavier with a longer wheelbase which made for less overhang off the back of the trailer. That towed very well. I think it had more out front, too, putting the engine farther forward on the trailer. The engine on the '64 sits pretty far back, relatively speaking.

    U-Haul suggested I check the tire pressures and I did - all good. There wasn't any wind. Might have been something goofy with the suspension on the trailer- I don't know.
  • I remember the last time I went to rent a U-Haul trailer, when we were hooking it up noticed the front frame on the trailer was bent, not a little but enough to notice it. We requested another trailer and they did not have one on the lot so we decided not to rent it at all. I have never rented from U-Haul since this experience.
  • The main cause of trailer sway is lack of tongue weight. Other possibilities are tires, suspension, wind, etc.

    Glad you made it safely.
  • was the car all the way forward on the trailer? sound like not enough tongue weight and to much overhang on the rear taking weight off the hitch.

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