Thickness of box and round frame tube.

[JakeDW]

I am on the last stretch of building my truck after I get it on the road and enjoy it for a bit I want to build a complete chassis for it while its in use.

I have always used 3/16 square/rectangle tube or 1 1/4 round tube.

I want to be able to bend the round tube.

So my question to build a complete frame how thick of material should be used.

I want the main chassis to be rectangular tube and k member ect to be round.

Thanks Jake

[tinydb84]

I am no expert but I have seen many builds on here and other site where they run .120 wall with rectangle tube. If you look at back half kits they are usually the same thickness.

They height of the frame plays a big factor though.

[JakeDW]

The truck will have air ride front back.

Jake

[SCOTI]

Originally Posted by tinydb84

I am no expert but I have seen many builds on here and other site where they run .120 wall with rectangle tube. If you look at back half kits they are usually the same thickness.

They height of the frame plays a big factor though.

Originally Posted by JakeDW

The truck will have air ride front back.

Frame rail height.

[JakeDW]

Originally Posted by SCOTI

Frame rail height.

Thinking 2x4 for the main rails

Jake

[PGSigns]

If not running a cage in the truck 2X6 would be better. Will be closer to the stiffness of a stock frame and will have a lot less flex than the 2X4.
Jimmy

[JakeDW]

Originally Posted by PGSigns

If not running a cage in the truck 2X6 would be better. Will be closer to the stiffness of a stock frame and will have a lot less flex than the 2X4.
Jimmy

That seams really tall it would not be stiff enough with front cross and k member and at least 3 other crossmembers in the bed area?


thanks jake

[tinydb84]

If you are running 1/8 wall 6 would be good. If you were doing 3/16 I would do 4.

[Snailed]

Ladder frames have terrible torsional strength because they have no height and little connecting the two sides. Most of the stuff offered out there for custom frames is .120 wall 2x4 and it's pretty flexy but has OK beam strength. I would do .120 2 x 6 mostly so you can make your cross members taller and try to get some torsional strength. If you are not trying to make stiff suspension work correctly then maybe it doesn't matter to you. Some air springs end up with a pretty low rate so torsional strength may not matter as much.

I would be curious how many pounds/degree a stock 60's truck frame would come in at in a torsion test. I bet it's about 900lbs/degree. A modern sedan is around ten times that and they handle as such.