5 ft. axle on a 4 ft. trailer?

[andreuther]

Has anyone aside from myself used a 5 ft. axle on a 4 ft. wide trailer? I got a screaming deal on a 4 ft wide trailer with full sized wheels on craigslist, but the trailer is only 4 ft. wide and my wife said the TD must be 5 ft. wide, and I agree. So I had my friend cut the 1.5 inch square axle and use a 4 ft. 2 inch sleeve to widen it 1 ft. This costed me a case of beer. The axle attaches to the trailer 6 inches from the frame. Has anyone else done this? If so has anyone had a problem with it? I built my TD to be removable from the trailer frame so that if there was ever an issue I could fix it. Thanks for your input.

[KCStudly]

Not sure that I can quite picture what you are describing, but I'll take a shot.

There should be no problem cutting an axle in the middle and extending it (or even shortening it within reason), so long as the "patch" is of adequate strength, is engineered properly, and the welds are sound.

Some things to be aware of are that some (most) axles come with camber (they are bent up in the middle so that the tops of the wheels tip out) to compensate for flex when loaded; and perhaps some toe (front of tires tipped toward each other) to promote good trailing characteristics and tire wear underway. On a dropped spindle axle (where the spindles are elevated or offset above the axle tube) it is more important to also keep the tube "clocked" the same when it goes back together; otherwise cargo load can induce twist in the axle (probably not a big concern unless you get really sloppy and miss by a couple of degrees or more). In and of itself this isn't catastrophic, but it may increase the number of load cycles the axle sees in this aspect over it's life cycle (i.e. a drop spindle axle will see different loads from side to side that tend to induce and relax in a twisting direction, but if you create a condition that guarantees that this will happen frequently and with more severity, it could come into play sooner rather than never).

What you do not want to do is to take a wider axle and move the spring perches in so far that you violate the makers specifications for hub face to spring perch distance. If you put the spring perches too far in from the hub face the leverage will magnify the load and may exceed the axles design capacity; that is you could bend or fail the axle under less weight than it is rated for if installed correctly.

For example, the Dexter D20 (2000 lb) straight axle has an overhang specification of between 5-3/4 inch and 7-5/8 inch.

The D30 (3000 lb) axle goes from 5-5/8 to 9 inches.

All that being said, someone will invariable speak up with a picture of the old pop up trailer frame where the middle rails and springs are 18 inches (or whatever) away from the spindles. That's fine, but who knows how that chassis was engineered, what the axle tube thickness is vs. the assigned capacity, and whether that company is still in business building them the same way. For that axle with that load, I am sure it is fine. For your axle with your load, it may be an apples to oranges comparison.

If you can identify the axle maker you should be able to look up or contact them for their spec (but you may want to keep the fact that you changed it's length to yourself. That is not significant compared to the load vs. leverage vs. axle tube strength relationship that occurs between the spring where the load is applied and the spindle where the load is transferred. The middle of the axle has more mechanical advantage (leverage) compared to the outside, so as long as it is as strong as it originally was, it is still under less stress than the outside.

On my tandem axle drop spindle car trailer with D35 axles that I bought surplus (take what you get) I made them a couple of inches wider by jigging them to a welding bench; indexing the spindles; cutting them in the middle; inserting a spud (the spud was round bar that had been drilled thru with a moderate size hole that would allow me to snake the brake wires thru, and had the ends turned down so that they would fit into the axle tubes on each side of the cut by several inches); and welding them all the way around. In addition to the circumferential welds, before inserting the spuds I drilled a few holes around the ends of the cut tubes almost to where the spuds would reach, and plug welded the tubes to the tips of the spud thru these holes.

[mikeschn]

Has anyone aside from myself used a 5 ft. axle on a 4 ft. wide trailer? I got a screaming deal on a 4 ft wide trailer with full sized wheels on craigslist, but the trailer is only 4 ft. wide and my wife said the TD must be 5 ft. wide, and I agree. So I had my friend cut the 1.5 inch square axle and use a 4 ft. 2 inch sleeve to widen it 1 ft. This costed me a case of beer. The axle attaches to the trailer 6 inches from the frame. Has anyone else done this? If so has anyone had a problem with it? I built my TD to be removable from the trailer frame so that if there was ever an issue I could fix it. Thanks for your input.

If the axle is not strong enough then the excess overhang will cause the axle to bend.

Lots of folks build a 5' wide on a 4' trailer, by tucking the wheels underneath the body.

Mike...

[KCStudly]

If the axle is not strong enough then the excess overhang will cause the axle to bend.

That's the Reader's Digest version of what I was trying to say. Cliffs Notes.

[andreuther]

I have no clue what brand the axle is. On center the springs attach 8'' from where the axle bends up. Here is a hand drawn picture of what it looks like. The total trailer weight is close to 1000 lbs.

[KCStudly]

Uh, yeah. That's not the way that I would have done it. Might be okay, though.

How far did you say the old axle slides into the new sleeve, and was it a sloppy or snug fit before welding? Is the 2 inch sleeve tubing (2 inch od x .25 wall thickness) or 1-1/2 nominal pipe (1.90 od x .145 wall)? If pipe, then the id is more like 1-5/8 inch and there is wiggle room ( not preferred, IMO).

Are there any plug welds inboard of the springs or is it just welded around where the two slip together?

You show the 8 inch measurement from about the middle of the drop forging. I'm not sure where Dexter's backspacing spec's are in reference to, but I suspect it is at the brake flange or wheel hub face. (Although some of the smaller numbers they list seem like it would not be possible if referencing the hub face, so... )

8 inches doesn't scare me too much.

The axle is already installed/in service? If so I think the thing to do is test it out with an empty camper first. Start by making a few short trips around the block, make sure to hit a few potholes or speed bumps (gentle) and inspect. Do it a little faster/longer and inspect again. Put some load on it and do it again; inspect. Eventually you will either see a problem developing, or you will gain confidence that the "fix" is sound for you application. Assuming that the workmanship and materials used are good, and that you don't overload like crazy, I doubt that it would fail dramatically (although if the weld cracks from fatigue you could loose an axle stub).

I'm not a lawyer and there is no way that I can offer you professional advice from a far, so you will have to decide for yourself (or get someone local to give you a second opinion). Translation: I would like to remain conservative on this one.

[andreuther]

My friend works as a professional welder for some heave equipment company so I am not worried about the strength of the sleeve. He did four plug welds and the 4 ft. sleeve was a very tight fit.
I will take you up on testing it gradually. Thanks for your help, I feel a little better about it now.

[KCStudly]

Yes, that sounds like he did it well. I fell better about it now, too, after hearing that.