Uging 3x3 for s-10 Stock Floors?

Originally posted by bdroppeddak



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.

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.......

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

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

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.

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.

s10 forum sucks

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?

also what is scrubby from aftermath using on his frame??? it looks like square tubing under the cab, its a 1999 blue s10 extcab on 24's front and rear

Originally posted by lunatiksblazer

i dont fully agree with it tho

I dont either. If I built my truck frame from one rail it would be applicable, but I dont, I build it from two parallel rails with crossmembers and gussets and braces. The laddering of the frame increases rigidity.

Art Morrison sells street frame kits, made with straight 5 ft sections under cab, made of mild steel in 2x4x.120. As soon as you change their mind, you will change mine.

This isnt a matter of a misguided minitrucker saying "it worked for me", this is one of the most respected chassis builders in the United States selling hundreds of frame kits a year for the last 20 years.

Thats the other thing about that deflection calculator, are they putting all the pressure right on the center of the beam with a hydraulic? Cause >correct me if i wrong? where the cab is connected to the frame or at the ends where it is gussetted? I think the deflection calculator was based on a single hydraulic pressing in the center of a beam, If im wrong please correct me like i said, But just wondering..

rusty 2x4 .120 is a HUGE difference from 2x3 .083..... when you get those rails here is what you do.... clamp one end down and push down on the other end.... if you read art morrisons website, look at what they say about their 2x3 .120 wall rails......... i wouldnt even want to think how little torsional stiffness that frame would have with that thin tubing.....