trailer frame material

[Rescue6]

So I bought an old M100 as a base. It came with a new 3500# dexter axle with 5on4.5” hubs and electric brakes. Brackets for a RTT that had been purchased. And a few other little odds and ends. With a title already. Got it all for under $400. The tub is in great shape as far as dents etc. it does have a small rust hole in the floor and the floor is pretty bent between the supports. The frame however. It has a crack on one side rail under one of the suspension mounts and the tongue was cut off and has been butchered pretty bad. So I’m going to build an new frame from scratch and put the tub onto it along with a new floor. Make the frame extended up front for the spare and a tongue box. It will have an extendable tongue as well. I also plan to build new fenders and extend the area front and rear of the fender to allow the areas to carry water tanks or fuel etc. I plan to run receiver stock front to rear. Then I’m trying to decide weather to build the rest of the frame out of 2x2 .120 wall or with something lighter like .095 wall. Or even going 2x3 .120 wall. The fenders and side platforms will be made using 1.25” .095wall tubing bent with my tube bender and skinned with steel. Anyway. What size frame do you guys with experience recommend I go with. I tend to overbuild things. I’ll be pulling it with a Jeep Tj on 1 ton axles, 37” tires, 5.13 gears, lockers, 4 speed t case etc etc. I plan on going with 33” or 35” tires in a 10.50 width for the trailer. I know that the Tj has a towing limitation that is pretty low. However with my stretched wheelbase, 1 ton axles and brakes along with the electric trailer brakes I think I’ll be ok towing it on and offroad. However I still don’t want it overbuilt and heavy as hell. Hoping once done and fully loaded I’m under 1500#
any help is appreciated.

 

[CampStewart]

I think 3x2 with the 3 vertical is better and for that matter 3x1.5 is better yet. If the tubing is welded to the metal bed than there is very little horizontal stress. .095 is probably ok but I would go ,120 If you want to gusset to spread the load around the spring mounts than thats great but 2 inch wide throughout the trailer is a waste. Running 2.5 inch receiver tubing front to rear is really heavy, I would run a 4 ft piece in the front extending 3ft in front of the box and 1ft piece in the back and connect them with something lighter along the lines of 2.5 x 1 x .125 angle lap welded on either side to connect the two

 

[Rescue6]

Yeah I really don’t want to run the 2.5x2.5 .250 wall front to back as it’s roughly 7 pounds per foot but I was thinking that it is really only about a 10 foot stick. So a total of 70#. And that would give me a four foot tongue in front of the trailer box. Then I could make an extendable 2” receiver slide in and out of up front for a little longer tongue in certain situations if needed. And would make for a super strong rear anchor point etc. If I did it the other way I was looking at like a 5.5 foot piece for the front section and another roughly 2 foot for the rear piece. That way it would tie into at least two cross rails front and rear. So I’d only save about 2.5 foot or like 18 pounds. I just thought what the hell. I’ll just run it the full length. I am still playing with my design drawings. And I do see a way I could do it with a shorter section up front but would need to do some gusseting for peace of mind. I may look into a 3x1.5 tubing. I had not even thought of that size. Thanks

 

[billiebob]

I'm a fan of 3x2..... I think on a per pound basis, 3x2 gives better strength per foot than square tubing, given the stresses/loads on a trailer. Why pick the heavier/weaker alternative ?

 

[old_CWO]

2x2 - .120 is plenty good for a quarter ton trailer frame and usually very common and affordable. Chassis made from that and an A frame tongue in 2x3 - .120. Good split between weight and strength in my observation. Tube thinner than .120 seems to dent up a little easy so I don't know if the lighter weight is worth the trade off.

Make your center cross members from angle instead of tube. They will be more than adequate and shed some weight and cost from the total.