Help
I'm in need of the formula too calculate the swaybar diameter, and the length of the arm needed for the rear of my milk truck. At times it can be just a little hairy . Just don't know why it doesn't handle like a go cart.

LOLOLO
Bob

I don't think you really want to make one, heating 4340 for the bends, blacksmithing the ends flat, then sending the whole thing out for heat treating. If you just want to compare different bars, the stiffness varies directly with the diameter to the 4th power and inversely with the length of the bar and the length of the arms squared. Look under some box vans and grab a bar you think will work.

Phil thanks for your concern! But I do have knowledge to fabricate a swaybar standard and adjustable. I've been a prototype metal model maker for thirty years here in Detroit. Over those years I've have made them, and had them heat treated.
I just want too do the calculation for my self. This one of those parts that needs to be just right, for a quality ride!
Did you know they now use hydraformed tubing for swaybars in production,some are 40-43 MM in dia 8 MM wall thickness for weight saving. (new Chevrolet Envoy for one)

thanks Bob

OK. This formula only calculated the stiffness factor K. You'll still need to apply it to lean, CG, etc.
K=500,000D**4
-------------
.4244A**2B+.2264C**3
Where D is the diameter of the bar. If you use a hollow bar it would be (D**4-d**4). B is the length of the bar between the arms, A is the distance from the centerline of the bar to the mounting point of the arm and C is the length of the arm from centerline of the bar to the mounting point since the arm may not be at 90 degrees to the bar. You'd have to compensate for these being hollow the same way in the calcs. heat the inside of the bends to yellow and use as large a radius as possible. Heat treat to 160,000 to 180,000 psi.