Effects of trailer brakes and sway

JBarca wrote:
The reason for this is, trailer axles have a toe setting built in from the factory.

I'd like to see a proper citation to support that claim. Camber is often built in, I've never seen anything saying toe is.

flhtci2006 wrote:
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.

Hi,

I may be able to add some to the discussion as I can see a several things going on and we do not know what happened exactly when.

First off, yes there is a front and back to the axle tubes. I am talking just about the axle tube at this point. You are correct, the wire hole is supposed to point to the rear of the trailer. The reason for this is, trailer axles have a toe setting built in from the factory. Depending on which axle manufacture makes them, they declare slightly different tolerances. You did not say if you had torsion axles or leaf springs as there are differences in them too. See here, scroll down a little and you can see the tolerancesTT axle alignment & install - Detailed (long lot's of pics)

Bottom line, the toe adjustment can be out of spec if you install the axle tube backwards. Wire hole to the front= backwards. If you manage to install it upside down, bottom on top and top on bottom, not likely but not impossible, the camber will be messed up.

The brakes have a left and right hand also. They do not work well when reversed.

When you took the trailer back, the shop could of goofed up a few things on the axle re-install to even more aggravate axle alignment to be worse. We need to be talking specifics here, the thrust angle on the front axle could be shifted out of spec if the play in the spring seat pin was excessive and fully skewed to the max play. This puts the front axle not square to the center of the trailer. Then the rear axle, assuming this is tandem, could be skewed the other way not making front and rear axle very aggravated in not being parallel. The axle alignment is now out, and if the hangers are welded on the trailer wrong from day 1, trust me it happens, then you can have a very out of aligned trailer grinding up rubber going down the road as the trailer is dog tracking the truck.

BUT... this mega out of aligned trailer will scrub tires badly but you may not get induced sway out of it that you feel "pending" other factors. You did not say what total weight the trailer was or what size truck you have. Do you have antisway control hitch? A heavy suspension truck can help hold this setup more stable then a soft sprung truck with soft tires on it.

Your hangers bent to the tune of the wheels being 2" shifted. This is another issue. We need more info on how your trailer is built. Especially if it is an I beam frame. Pics of the hangers and frame will help greatly. Trailers now a days have many axle hangers issues and are no where considered heavy duty. The side flex of the hanger into an unsupported I beam frame can and will crack the frame web over time. The lower flange of the I beam is so weak it flexes without much side thrust. The hangers if they are the long ones, 3 to 5" long, and have no extra support will bend in turns OR high up and overs on off road travel. The toy hauler guys who go off road often, sometimes reinforce their hangers before they start going in the outback.

Heat in your tires: Between possible axle alignment issues from the shop, bent hangers that then totally messed up the axle alignment, you can easily get heat from tire scrub against the road and it can affect your gas mileage if it is bad enough. You are dragging the trailer down the road rather then rolling it down the road.

Now to the brakes. I just helped my neighbor troubleshoot his brakes. He has a 28 foot, approx 6,500# trailer being towed with a 1 ton SRW Dodge Ram. Only 1 trailer wheel had any kind of braking. The front axle, both sides the wires were broke and on the rear axle, one wheel had a broken magnet coil inside the wheel. He only had 1 brake that had power to the magnet coil and it was very far out of adjustment. That 1 wheel was trying to stop the camper and not doing a very good job of it. There was no sway and the 1 ton truck was doing the braking.

On my camper, 32 foot, just under 10,000# loaded. I installed self adjusting brakes. One brake drum had 0.020" out of round runout to it and that allowed the self adjusting brake to adjust into that out of round and ended up over adjusting it. We are towing to camp and I am in town. I start out from the red light and the truck is up shifting very different. After a short distance of this I pull over and one wheel is smoking hot on the brake. Oh boy.. Let it cool, crawl under and un-adjust it. Here I have been towing out on the highway with a partially locked on brake. And before I could get home, I had to stop a second time and unadjust the brake for the same thing. Point is, I had one wheel almost totally locked on and I'm towing at speed with it. With the mass of the trailer and the size of the 1 ton truck, there was no sway.

To your situation, your rig started swaying on the way back from the shop. First tell us the weight of the camper and the size of the truck. Do you have and anti-sway WD hitch? Think back in your mind, when did the sway start to happen during your trip? Immediately when you left the shop and made it over 45mph or less? Was it after 30 miles of towing above 45mph? or less. There are a lot of factors in what went wrong. This one is not going to be simple to pin point. Once your hangers bent, that is a totally different scenario. The trailer is then severely out of wheel alignment. When was the sway in relation to when the hangers being bent? When did you realize the hangers bent?

Your going to need to find a better shop to do the repair, verify the axle alignment and correct as needed and if your hangers bent, odds are high your frame and hangers are going to need to be addressed so it does not happen again.

Really curious on how this will all play out. We too learn from you on these kinds of situations.

Hope this helps.

John

I believe trailer axles have a little toe in. If the axle is reversed then the axle will have toe out which could possibly aggravate a trailer that is already close to wanting to sway.

My father had a front end shop and he always gave trailer axles a little toe in.

The only way trailer brakes could induce sway is if they pulsed only one side with high power and perfect timing. And that's a big stretch.

More often, applying the trailer brakes will stop sway. That's how the new truck "anti-sway" features operate. They apply the trailer brakes. (In some rare cases, this proves to kill MPG's and create an unpleasant towing experience)


Sounds to me that your dealer messed up installing/reinstalling your axles, they are probably misaligned now, and no way in H E double L is any of that your fault if you never put a wrench on it!

An dragging brake will pull the trailer to one side, and CONTINUE to pull the trailer to one side. It won't cause sway, because it's still pulling the trailer to that one side, a stabilizing force. It would pull crooked but it won't sway.

Now if that force suddenly went away, and then returned, repeatedly, at the right frequency, then it might induce sway. However, that's a scenario you are not going to encounter out "in nature." It would have to be artificially induced, by manually applying and releasing the trailer brake. No person in their right mind would intentionally do something like that, so if you're in your right mind you have nothing to worry about.

Over time, the dragging brake will build up heat and gradually lose effectiveness. As this happens the trailer will move back toward pulling straight again.

Weird, other than auto adjusters on drum brakes I cant see any other adverse effects to installing a straight leaf spring trailer axle backwards.
Can’t explain the sway issue.

Turtle n Peeps wrote:
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.

I agree and like you over the years have had various combos of brakes up to three fail due to wiring issues, mainly broke wires. Never even a hint of any adverse effect on the handling of the trailer except for lack of stopping power.

Larry

It's a toy hauler and at the furthest back was my trike. Remember, I drove the same road to the facility with the exact same load with no issues. Also, per Lippert the data plate on the axle is to face rearward. This also will put the brake wire exit holes from the axle going rearward. Heartland has a recall out for axles installed backwards. So yes, they can be put on backwards and upside down.

How can spring axles get installed backwards? Only the brakes are handed, and swapping brakes side-to-side is easier than reversing an axle.

Downhill makes sway more likely, there's less pull to drag the trailer into line, and braking can amplify the sway, especially if the vehicle/trailer braking isn't in balance. With new axles/brakes, that may have been the case - the trailer brakes wouldn't have been broken in.

The relationship between sway and tongue weight is only a rough rule-of-thumb.

The actual loading is more important - weight near the axle is good, weight at the front and back extremes is bad, since the former doesn't increase stability and the latter creates a greater moment of inertia.

To picture why, think of a large weight on the very front of the tongue, maybe directly over the ball - it adds lots of tongue weight, but does next to nothing for stability. Same for propane cylinders and batteries on the tongue - even if you're at 15% tongue weight in static balance, they don't offset (for sway) weight in rear storage, which has lot of inertia once sway begins.

I once found, but lost, a good physics exposition of weight distribution vs. sway. Basically, the "forward" weight is best when it's concentrated about half way between the axles and hitch. Rear weight should be as close to the axle as possible.

Speed was 35mph increasing to 45-50mph.