darn you max(frame size revisited)

Max why could you not have been discussing all this stuff on material size 8 months ago. Here's where I'm at. I'm working on my 74 crew cab dually, I purchased 2 lengths of 4x2 .250 wall rectangular tubing, and having my notches cut out of .250 thick sheet. Now you got me second guessing myself. Is there any real downside to this thick and heavy of a frame except for the weight? You know if you would have mentioned all this earlier I could have saved some money, so I blame you.

or you could have reassurance your thicker material is more than likely a good thing on such a heavy ass truck.

the strength of tubing is in that its a tube, not just in the wall thickness. by the same degree, the strength of a frame is in its ladder design, not in the wall thickness. frames need to have "give", if they dont, they will break at the weakest joint. Even big truck frames, I should say ESPECIALLY big truck frames, are built to allow for torsional twist for energy transfer. Anyone remember the ford commercial where they deflected the truck frame 8 inches or so on one corner? The only thing you gain with a heavy frame is a low center of gravity.

and you will really regret trying to weld that 1/4 to the 1/16th thick original frame, because if the weld gets hot enough to penetrate the 1/4 you are USUALLY blasting clean through the 1/16th.

russ is right in all accounts. if you dont run hot on the 1/4 and "pull the bead" over to the 1/16 and back to the 1/4.......your f*cked.

1/16?? thats sheetmetal, frames are at least 1/8"

my 89 ramcharger is almost 3/16 thick stock. and its a 2wd, 106" wheelbase truck. im sure your frame is thick as hell. but, overkill i guess.

Russ-D is right about the frame flex issue. There are many, many frames out there that are over-built and so would be considered poorly engineered. That doesn't mean that you should sell your tubing and start over though. When attaching the new frame section to the stock frame, be sure to use fish-plates to spread the stress out over the weld joint (there have been a few threads about the subject). It's really tough for me to explain all of the little stuff to watch out for. Engineering is not something easily explained, but if you try to imagine where all of the stresses are going as things flex and try to eliminate any of the obvious problems, you should be alright.

sorry, I said 1/16 but I meant 1/8. although the inside quarter of my mazda frame was thinner than that. maybe not 1/16, but not more than 3/32.

I just measured the stock frame it is .225 so I don't think I'm to heavy. I had measured a c-10 frame before.

Originally posted by BioMax



Russ-D is right about the frame flex issue. There are many, many frames out there that are over-built and so would be considered poorly engineered. That doesn't mean that you should sell your tubing and start over though. When attaching the new frame section to the stock frame, be sure to use fish-plates to spread the stress out over the weld joint (there have been a few threads about the subject). It's really tough for me to explain all of the little stuff to watch out for. Engineering is not something easily explained, but if you try to imagine where all of the stresses are going as things flex and try to eliminate any of the obvious problems, you should be alright.

max, technically isnt a 2x3 1/8 inch frame weaker than a 2x5 1/8 frame? by loosing the height isnt it more prone to flexing length wise? so using a thicker frame material would make it as stiff as the factory unit. i'm not so much questioning you as i am making sure that i could safely build a full frame with thinner(and cheaper)material. plus i can weld 1/8 inch with my welder, to build a frame with 3/16 or 1/4 id have to buy a new welder.