Overbuilt trailer? (2x2x1/8)

[GeoDrop]

I am building variation of a Grumman 2. It is 5ft by 10ft long. I had a trailer professionally welded using 2x2x1/8" (11 gauge) square steel tube. I was a bit shocked by the weight of the trailer when I picked it up. (Don't have an actual weight). Since we are intending to tow with a car, I've been trying to keep it light. (Design is basically a 2x2 square around the perimeter with two cross members made of angle)

Did I have him use the wrong thickness? @ 3.05 lb/ft for 11 gauge I figure about 140lbs. If I went down to 14ga, that is 2.16 lb/ft, that would save me about 40lbs. But I would be worried then about too much flex in the trailer.

Am I over-reacting!? I need to weigh the trailer and figure out exactly how much it does weigh.

[Cliffmeister2000]

Once you have a box on the trailer, it won't be able to flex. 2x2 is very popular, I would think 1/8 inch just about right, but I'm no metalworker. Mine is 5x10x5, and the frame is 1-1/2" angle iron. Very strong so far.

[asianflava]

This is the frame I built for my tear, it's all built out of 2X2X1/8. I had to change the tongue to 2X4X3/16 because they didn't have the 2X3X3/16 that I really wanted.

As mentioned, the box is very strong. The cabinets and shelves act like full length gussets that prevent it from racking.

[bobhenry]

I will confess I didn't build the frame for the barn. However the one I built on had been overloaded some time in its life and the second crossmember was bent downward about 2". I do not like putting all that down force on just that one member. There is about a 4 to one lever advantage on that first member so 100 pounds of tongue weight at the ball is 400 pounds of down force at that 2nd cross member. Add a pot hole and a big dip in the road and you have some serious force. I used 2x2x3/16 and as several on the board told me it was not enough I had some serious flexing. I do feel I did one thing right I ran the tongue clear to the rear of the frame. Yes it added another 15 +/- pounds but it did two things it greatly reduced the lever advantage at the end of the tongue and gave me a light duty receiver by shimming a bit with some 1/8 flat stock so I could install a 1 1/4 class 2 draw bar. In the shivaree pic you can see how I canceled out the flexing problem by making a bow truss. I placed a stub of 1 1/4 steel tube at the first crossmember

( yes in the pic the 1st crossmember is 2 foot back, the barn is cantilivered 2' forward)

then added a length of 1 1/4 by 1/8 flat stock. The flat stock ran approx. 4 feet each direction. We welded both ends and then with the aid of a hugh old "C" clamp drew the strap down and welded the side seams. This was done front and rear to tension the flat stock. When we were done it sounded like a bass chello when you slapped it. Took all the flex away. As you apply up lift at the ball the rear strap is tensioned and lift occures at the stub to lift the front crossmember.

I was never concerned with the box portion of the frame as the shell offers a great deal of assist to it but the tongue connections always scared the hell out of me I have seen pics of 3 tongue failures here on the forum and have seen the aftermath of 2 at roadside. At interstate speed it is a 1/4 mile path of broken parts, pots and pans, dishes, clothes and it is ugly.

[john]

Over time I have come to realize that the only things the frame truly provides for a TD is a place for your wheels to mount and a place for a hitch.

Andrew (angib) made the point with this frame.



A frame is not needed for supporting the floor or to resist racking. Torsional rigidity is provided for by the 'box' design of the tear drop. In essence the tear drop provides the torsional rigidity for the frame.

The weight of the teardrop or ttt is transferred to the axle through the wall and not the floor so a thick floor is not needed to 'carry the weight' and all you are left with for the floor to do after adding torsional strength in the completing the box of the tear, is to support youy sleeping or crawling body and the framing required for the suspension and hitch is more than enough to provide the floor the support needed for that use.

4X4 off roaders on the other hand....


I bent the frame below playing teeter-totter on it with one of my kids. I later straightened it by mounting the TTT walls to it. Most of it is 1x2x1/8 C channel. The smaller stuff for the drop floor is 1x1x1/8 angle. If not for the framing for the stub axles and the drop floor, this frame would have weighed around 1/4 to 1/3 less than it does. It weighs approximately 225 lbs.

[Dale M.]

Here is mine... 5' X 9' using 2" x 2" x 1/8" for frame and 3" x 3" X 1/8" for tongue.....



I intend to do a little off road behind the Jeep (not Honda in picture) and wanted something I can depend on.... At some point worrying about keeping it really "lite" starts bordering on safety.... Rather be slightly over built than under built...

Dale

[GeoDrop]

Thanks for everyone's input. I semi-committed to keeping what I have by wire brushing it today and getting a first coat of paint on it.

[doug hodder]

It may be a bit much...but on your first one, that's not such a bad thing to have. Gives you confidence. I've built a number in 1/8". I've built as light as 16 ga, but kept the tongue in the 1/8". What will flip you out on the lighter stuff is just how much action you get out of the frame jumping on it...once it's all together...it's not an issue. You'll be fine...build with confidence. Doug

[kennyrayandersen]

I think Gus brings up some really good points. Your removable ‘box’ will have posts that insert into your trailer, right? Why not put a floor in your box and the posts would serve to keep the box off the ground when it’s not on the trailer. That way you won’t have to worry about the bottom getting messed up. It looks like you have 4 posts on either side that are lower and at the same level. If you made a minimal frame and a ‘structural box, then it would be HEAPS lighter. You could use lighter gage steel as Gus suggested for the 8 support posts, or frankly you could even use wood. Since you aren’t on some ultimate weight-saving mission (like me ), I think this would be a really good application for the paper-covered foam core used in roofing (there were some previous posts on that stuff but I can’t remember what it’s called – hopefully someone will chime in). It’s not so expensive. It’s around 2 inches thick, and has a paper bonded to both sides. You could build the box out of that foam sheet and then add fiberglass, or you could even bond plywood to the foam and you’d have an incredibly strong sandwich; plus, it would be MUCH lighter than building a steel frame – just something to think about.