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Question regarding Ladder Bars

Discussion in 'The Hokey Ass Message Board' started by Fatrod, Oct 22, 2008.

  1. Hi All,

    I'm just about to start making the ladder bars for my 32 Roadster. I was planning to use 1" 303 stainless round bar. However all the kits you can buy use .156 tube. Apart from the weight and I guess a little flexing is there any reason for this?

    Can I use the Round bar or should I use tube with is about 5 times the price of the bar!

    Thanks in advance

    Chris
     
  2. alchemy
    Joined: Sep 27, 2002
    Posts: 18,339

    alchemy
    Member

    A lot of weight, doncha think?!
     
  3. v8 Bake
    Joined: Dec 23, 2007
    Posts: 296

    v8 Bake
    Member

    I made my 4 bar from 1 in hex shaft.They are very short so when I drilled them in the lathe the holes nearly conect and they are still heavy but it will work.
     
  4. Shifty Shifterton
    Joined: Oct 1, 2006
    Posts: 4,964

    Shifty Shifterton
    Member

    If you look at how a tube carries stress, the majority of it is thru the skin. All that extra weight down the center doesn't carry the same strength per pound as the little circle of mass around the edge.

    It's also unsprung mass. Super heavy suspension arms need bigger bumps/more energy to initiate movement.
     

  5. Andy
    Joined: Nov 17, 2002
    Posts: 4,940

    Andy
    Member

    Tube is stronger per weight but bar is stronger. If tube was stronger you could increase strength by reducing wall thickness untill it was really strong and no wall at all. Think about it. I used bar for my front radius rods,. The difference in weight was minor. Only downside is tapping holes without a hole in the center. A lathe fixes that.
     
  6. 7/8" .156 wall tubing can be easily drilled and taped for 5/8" fine thread rod ends and cleviceses (sp).

    Use the DOM. It is more expensive and well worth the price.
     
  7. Andy
    Joined: Nov 17, 2002
    Posts: 4,940

    Andy
    Member

    Tube weighs 1.19 lb/ft. Solid 2.04. Saving .84 lb/ ft. If radius rods are 30in x 4=120 in--Saving of weight would be 8.4 lb. I am cheap so used solid. Stronger too!
     
  8. 7/8" x .156 wall is used by the aftermarket because it's the right wall thickness for 11/16-18 taps.

    7/8 x .156 is commonly used for tie rods and drag links as well as radius rods.

    11/16" x 18 is the thread size used on Ford tie rod ends.


    1" x .156 is correct for 3/4-16 which is the Ford truck tie rod end size if I remember right.

    You can use 1" x .120 wall for rear 4-bars and ladder bars.
    There's not enough wall thickness to use 3/4-16 rod ends, but you can drill it out and tap it with a Helicoil tap for 3/4-16 and install a Helicoil thread repair piece.


    Speedway also sells threaded bungs for a modest price that you can weld into the tubing of your choice.
     
  9. Thanks everyone. I'm going to look at the cost of the tubing again. I have a lathe so machine is no problem.
     
  10. DollaBill
    Joined: Dec 23, 2003
    Posts: 372

    DollaBill
    Member

    Fatrod

    The basic premise is that, pound for pound, tubing is stronger than bar. This is predicated on the fact that tubing has TWO surfaces with which to inhibit axial deformation.

    Of course, there is a standard, relative to a given tubes diameter, that specifies a particular wall thickness for the particular application.

    C9 makes a great point, as well, relative to common tube sizes...they are far easier to fabricate with because they have "standard" wall thicknesses to faciltate common rod ends.

    Obviously, a propely fabricated ladder bar could be built from bar, tube, (round or square), flat stock, mild steel, stainless...it's all been done.

    I would go with the tubing that "fits" the rod ends you plan on using
     

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