Effects of trailer brakes and sway

You don't say how fast you pull, higher speed induces more sway, if you're getting enough sway to bend stuff, you're going too fast.

So here's the deal: My trailer was loaded to 400 pounds below max weight. Tongue weight percentage was 12.3. I had just gotten the trailer back from a "repair" facility and was getting ready to head to the east coast. I happened to notice they had installed the axles backwards, rt vs lt, not up vs down. I drove back to the shop to have them reverse the axles (130 miles). They reversed the axles and I headed home. The trailer had minor sway which I thought was canyon winds. Also, the truck was working harder and gas mileage dropped from 8.9mpg to 5.8mpg. Also, two tires were running 45º hotter than the other two. Slowed to 35mph in a construction area on a 7º down grade. Upon exiting the construction doing 35, I proceeded to speed up due to the grade. The trailer then swayed dramatically and caused all 6 hanger brackets to bend, shifting the axles 2 inches to the left. The road was straight with no bumps. They are saying it's my fault. There are a lot of mistakes they made prior to this (which is why they installed new axles...backwards) that really isn't pertinent.

Long answer short; no.

I have had a wire go bad on my trailer brakes many times. No sway. In fact I would not likely know if it wasn't for the error code on my controller.

Typically trailer brakes are wired in parallel. A cable runs down the left trailer frame. Then from each brake on left side to the brakes on the right side.

The brakes to the rear have a couple more feet of wire to the magnet.

The brakes on the right side have at least 7 feet more wire to the magnets.

Due to voltage drop the right hand brakes will receive less current thus less braking effort than the brakes on the left side. Same for the rear brakes.

The difference is small and most likely is of little consequence.

But under a certain braking situation possible for left front brake to lockup before the others.

I would say yes it could cause the trailer to sway. Any side /lateral force can induce sway so a miss adjusted, improperly installed, or broken brake assembly can cause a sudden pull to one side. Pull the drums and take a look if that’s what you suspect.

flhtci2006 wrote:
is there a brake situation that could better induce sway,

Yes. If one side brakes harder than the other, that produces a sideways force which starts a sway.

Whether that sway dampens out or builds then depends on other factors. It's not just tongue weight.

Putting tension on the hitch reduces sway. I would expect that the additional tension applied to the hitch by any dragging brakes would do more to counteract any potential sway than any instability/imbalance caused by uneven brake application/sticking.

Unequal braking on one side could but with 12% tongue weight it should stop on it's own.

little,

electrical brakes (all 4) receive equal power.
mechanical problems... one wheel could drag and might cause to trailer to pull to one side... slightly.. and the HEAT will soon destroy that brake.

so a possible intermittent issue could cause sway.. but limited in time.
and it would have to happen that the same point in time... like every 2 seconds... to cause sway.
a none even event should NOT cause a sway.

my opinion.