Posted: Monday, February 05, 2007 4:07 PM  

Posted: Monday, February 05, 2007 4:18 PM  

I've always wondered about that as well, even a 2x2 is thicker than most stock frames. It would also give a lot more room that using a 3x3. Also, is there a difference in using a 2x3 upright or on its side?

Posted: Monday, February 05, 2007 4:28 PM  

2x3 at least .120 wall is fine. think of it this way, 2x3 .083 wall is what we use to make our frames fro 1000hp pro street cars.. (of course they have cages built also...)

IfItsGotWheels.com

Posted: Monday, February 05, 2007 4:41 PM  

Rectangular tubing is stronger than square. This is why stock frames are rectangular and not square. Use 2X3" 1/4" wall and 3/16" wall on shorter runs and crossmembers.

Posted: Monday, February 05, 2007 4:46 PM  

so is there a difference in using a 2x3 with 2" high instead of 3" high?

Posted: Monday, February 05, 2007 4:49 PM  

I am doing 2x3x3/16 on mine, but only under the cab, the back half will be 2x3x.083. Using 7 ga for plating. I am doing the 2x3 with the 3 up though.

Posted: Monday, February 05, 2007 5:26 PM  

Factory Frames are highly engineered. Every bend, contour, and dimension has a purpose. The average guy building a minitruck in his driveway isnt taking much into account other then body mount placement and keeping it level and square. Overbuilding compenastes (somewhat) for the lack of engineering. That being said, 2x2 simply does not have the vertical strenth you need and it will flex. 2x3 standing vertical 3/16 wall is the minum i would build with from the front to the back of the cab. What is the point of running 2x2 anyways?? You might save your floor pans, but you still need more then 2" to run exhaust and it doesnt give you much space to build bodymounts etc..

Posted: Monday, February 05, 2007 7:48 PM  

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Originally posted by Russ-D
I am doing 2x3x3/16 on mine, but only under the cab, the back half will be 2x3x.083. Using 7 ga for plating. I am doing the 2x3 with the 3 up though.

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rusty i hope you are putting a 12 point cage on that frame, that 3x2 .083 will flex like a mother, i just built a frame from 3x2 .120 wall and used a bit of round tubing to triangulate the rear of the frame behind the cab and make sort of a "backbone" down the center to take alot of the flex out of it.......

-------- every day above the ground is a good day.

Posted: Monday, February 05, 2007 8:04 PM  

3/16 and 1/4 wall are needed if you are going to drag the piss out of it. If you are not going to drag it you can use thinner tubing with proper cross bracing. Most race cars use the roll cage to keep the car from flexing. with out a roll cage your frame needs more bracing to keep it from twisting and bowing. 2x2 or 2x3 laid on its side will bow and twist unless there is some kind of bracing through the cab.

Posted: Monday, February 05, 2007 8:59 PM  

thanks for answering all the questions, so are you guys taking into consideration that the tube is welded on both sides and gussetted at both ends? are you guys judging flex with or without solid ends and also w/ prolly 3/16" 1/2way boxed around it also? i wish someone would take there old frame that there build a firewall back, cut it right behind where the cab would end and the bar be gussetted and then cut it out and attached it to something and do a real world test of how much weight the truck would put on that peice, cause all these flex calculators dont put all this into consideration it seems like. i realize that cage and triangulation strengthen the hell out ofrace car frames but still. like ILL said arewe just making up for not completly understand what were doing? I use 2x3 standing up, i wasjust simply asking if 2x2 would work, but aparently it flexes too much.

Posted: Monday, February 05, 2007 9:06 PM  

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Originally posted by bdroppeddak


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Originally posted by Russ-D
I am doing 2x3x3/16 on mine, but only under the cab, the back half will be 2x3x.083. Using 7 ga for plating. I am doing the 2x3 with the 3 up though.

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rusty i hope you are putting a 12 point cage on that frame, that 3x2 .083 will flex like a mother, i just built a frame from 3x2 .120 wall and used a bit of round tubing to triangulate the rear of the frame behind the cab and make sort of a "backbone" down the center to take alot of the flex out of it.......

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it will have crossmembers on the backhalf, and the tubing is mandrel bent. I'm 1000 percent confident in my choice.

Posted: Monday, February 05, 2007 9:22 PM  

well, im surprised i havent seen biomax in this forum yet because im sure he can answer this. But im a mechanical engineer major and we were talkin about this between a few of us at school that builds cars to. I have seen the table on s10forum about wat size tube to use, i dont fully agree with it tho. But us pluggin through some equations i have found that delfection gets less the bigger the tube. I can work this out for you if you tell me what type of steel the tubing is (for example 1020cr, 1040cr). Ive been actually wanting to do this so someone just tell me what type of steel. Ill do it between dodging the exams

I dont care if you say it can't be done, I'll do it! I have the scares to prove I built my rides.

Posted: Monday, February 05, 2007 9:25 PM  

For more of a reference, you can check out this chart on s10forum (youll need to be logged in to view it): http://www.s10forum.com/forum/f143/those-wit-sfbd-frame-size-qs-68110/ It shows that a simple piece of 2x2x1/4 that you propose to build a frame out of has more than 7 times (2.63") the deflection of the stock frame (.36") with 1000lbs across a 5' beam. I wouldnt even get on the same road as a truck like that.

~Serving the Tri-state: New Jersey - New York - Pennsylvania~

Posted: Monday, February 05, 2007 9:33 PM  

thanks very much for explaining this to us people that didn't know, I always like learning more and getting to understand better why things are done certain ways. And it does really Help when its not a bunch of guys saying not to do anything and just leave it all alone. Nobody learns that way either.

Posted: Monday, February 05, 2007 9:35 PM  

s10 forum sucks

Posted: Monday, February 05, 2007 9:53 PM  

a friend of mine and me were talkin about this about a year ago and he was plannin on doin a quad cab dually, and tossing around the idea of using2x3x1/4 or better on its side with 2-3 inserts of some super thick square tubing then welded the ends together and capped the ends.. and i was thinkin the same thing like why it wouldnt work if your adding internal walls to the rectangular tubing. and have properly placed crossmembers and maybe some extra round tubing to run along the driveshaft. ??? i understand the deflection. and i know that the longer the material the more leverage that can be exerted on it. but what if you were using rect. tubing on its side and all that i mentioned on a midsize or minitruck?

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