Ladder bar material question.

I am doing a bucket style roadster. I have radius arm setup on the front. I have decided to do ladder bars on the back ouside of frame, about 3.5 feet long as a replacement for hairpins that came on the car. These will work like the hairpin, but be much beefier with the bushing ends, etc.
I bought 1 1/2" thick wall steel pipe to make these from. The pipe has a seam, because it is not DOM. Anyway, I would think that being a ladder bar with the triangulated braces would really help the strength, plus I'm running two pipes to the rear. I thought about running a bead along the outside of the pipe seam as a preventative measure, such as Henry Ford did on the front radius rods. Am I over-anylizing the possible weakness of the pipe seam? I wouldn't think that I would HAVE to build the bars from DOM tubing since I'm using pipe more than three times the diameter of a hairpin. Any thoughts? Thanks.

 

i've always made rear ladder bars from 7/8" OD DOM tubing. when you say "pipe" do you really mean pipe..the stuff they plumb with? what is wrong with the hairpins you have now? we need to see some pictures

 

Don't use pipe,too weak as said use 7/8 tube tap to 5/8

 

If you're using 1-1/2" black pipe, and triangulated, you will be fine. No way you will break that. Might get kind of heavy, at nearly 10' of material per side.

Get ready, nobody else here will like this.

 

1 1/2" will look HUGE on the side of a small car like that. As posted above, 7/8 or 1" DOM will be more than adequate when you brace it.

 

I believe that you have RSW (resistance seam welded) tubing. Which should be fine. I wouldn't run a bead of weld over it, too much like work for no added value. Plus it will look fugly when you're done.

For the size, eyeball it up to another similar build if you want, but over a length of 3.5' you should be ok with the 1.5 diameter tubing. Make sure the ID size can be drilled and tapped for your heim fitting or whatever you want to plug into it.

Bob

 

As others have pointed out, 1 1/2" tubing ain't gonna look right, mock it up with shipping tube and you'll see what they mean. 7/8 dom is small for me, i'd go 1" X .134 wall and tap to 3/4" (like a drag race ladder bar), since it is visible the proportions (tube size/length vs body panels/frame) would look professional.

 

Thanks for your replies, I didn't see the replies right away and built them from 1 1/2 RSW pipe. They do look big, but I think it will blend in well. I went this big to kindof mock the front radius rods made by Henry Ford. Here's a pic, so laugh if you want.

 

If you can't swing DOM tubing at the very least get yourself some mechanical tubing. 1.5 is large BTW. 3/4" to 1" is a gracious plenty I've seen built with 5/8 that held up on a light vehicle.

 

I use 1" OD tube for rears and would only use seamless, the one problem that hasn't been mentioned is that the rear axle won't articulate very far with the wishbones on the outside of the frame.