Harbor Freight 4x8 Center Beam or overengineering?

[AgentOrange]

I am starting construction on a HF 4x8 folding trailer with my squaredrop platform being 5x10. Its gonna be a foamie so I expect well under 1000lbs, and I expect to be mild terrain if not all highway. My tow vehicle is an Outback. I have an opportunity to add a center beam (1/8 square tube) and attaching it from tongue to the first crossbar member. Was thinking bolts but it could be welded. My question, what does adding a center beam buy you for the above specs?

A bigger question...how do you define over-engineering? Is there such a thing? Would it be "doing something or adding materials that do not add to preclude any feasible eventuality". If so, then is there acceptable over-engineering (some eventuality, but remote) and ludicrous over-engineering (will not help in any eventuality)? Is there middle ground? Without having the requisite experience, I suppose the first instinct is to over-engineer.

 

[Brumasterm01]

While, I can't speak to the structural integrity of adding a "backbone" to the trailer. I can tell you that bolting a 12' 2”x2” .120” wall square tube "backbone" to my Harbor Freight was one of the easier tasks when building my square drop.

Simple mark, drill and attach 3/8" hardened bolts. I also see no reason why this could not be done after building the cabin, if you were so inclined. All my bolts are still accessible after the build, since they are attached to the bottom of the frame.

 

[Pmullen503]

While, I can't speak to the structural integrity of adding a "backbone" to the trailer. I can tell you that bolting a 12' 2”x2” .120” wall square tube "backbone" to my Harbor Freight was one of the easier tasks when building my square drop.

Simple mark, drill and attach 3/8" hardened bolts. I also see no reason why this could not be done after building the cabin, if you were so inclined. All my bolts are still accessible after the build, since they are attached to the bottom of the frame.

I did the same to lengthen the tongue on an HF trailer. I ran it to the cross member just past the center. I welded tabs at each cross member and front and bolted it to those. New diagonals were made from C channel. I was happy with the result.

You can no longer use the tilt or fold features however.

 

[QueticoBill]

I added a 2x2 tube to both extend hitch a little and leave too for a box AND because I saw failures were often where the wish bone members cross the first frame piece. Mine went to 3rd cross member. All bolted.

 

[AgentOrange]

While, I can't speak to the structural integrity of adding a "backbone" to the trailer. I can tell you that bolting a 12' 2”x2” .120” wall square tube "backbone" to my Harbor Freight was one of the easier tasks when building my square drop.

Simple mark, drill and attach 3/8" hardened bolts. I also see no reason why this could not be done after building the cabin, if you were so inclined. All my bolts are still accessible after the build, since they are attached to the bottom of the frame.

Well, gosh darn...it didn't even occur to me that I could lengthen the tongue...great idea and I just might need to.

So aside from what seems to be the universal reason was to lengthen the tongue, I will assume that there is no huge stability advantage to adding a 'backbone' if you're not offroading, etc.

 

[AgentOrange]

I added a 2x2 tube to both extend hitch a little and leave too for a box AND because I saw failures were often where the wish bone members cross the first frame piece. Mine went to 3rd cross member. All bolted.

The failures you refer to at the wishbone where they cross the first crossmember, if I remember correctly is where there are hitch pins (to fold the tongue down). I have replaced those with bolts.

What are the kinds of failures, can you elaborate?

 

[Brumasterm01]

Well, gosh darn...it didn't even occur to me that I could lengthen the tongue...great idea and I just might need to.

So aside from what seems to be the universal reason was to lengthen the tongue, I will assume that there is no huge stability advantage to adding a 'backbone' if you're not offroading, etc.

My motivation was to increase structural integrity specifically for offroad. I saw others using a backbone for offroad HF trailers builds. (https://tventuring.com/how-to-enhance-a-harbor-freight-frame-for-use-unde-t888.html).
I eventually wanted a bit of lift and bigger tires too. Being my first build and not an engineer, I adopted the "Monkey- See-Monkey Do" approach.

The longer tongue is a byproduct of the 2"x2" steel tube. The standard length was 12'. It would have cost more to have it cut to a smaller size. It also gave me a few inches overhang off the stern to add hitch.

In my smallish noodle it seemed that dragging one solid steel tube tongue to aft (that everything bolts to) made sense. Was it necessary? I don't know. It does give me peace of mind.

 

[QueticoBill]

The failures you refer to at the wishbone where they cross the first crossmember, if I remember correctly is where there are hitch pins (to fold the tongue down). I have replaced those with bolts.

What are the kinds of failures, can you elaborate?

I have seen more than one picture on this site of a trailer the "folded" at that point - the two pieces of the wishbone or "A" bent. You could reinforce those members. I found the tube in the midfke easier plus the lengthening.

 

[QueticoBill]

The longer tongue is a byproduct of the 2"x2" steel tube. The standard length was 12'. It would have cost more to have it cut to a smaller size. It also gave me a few inches overhang off the stern to add hitch.

I would have liked to extend it to rear but I underslung the axel which prevented the tube from going that far.