i pulled my 1 1/4 hotchkis sway bar off and found it was hollow,so it seems to me it would be weaker than a solid bar,i know tubeing is strong but on a twisting motion i would think it would fatige,i dont see springs made hollow, anybody do any testing on this

the hollow bars work all our oval track/road race bars are hollow.

Size for size, tubing is almost as strong as a solid bar. If strength is an issue, you step up to the next size tube. That's why they make race cars out of tube and not solid bars. I would have to dig out my "Strengths and Properties of Materials" books from college to be able to prove it but it's true. Yes there is less material but most of the force acts on the largest diameter so the missing material in the center doesn't influence things all that much.
I'd be more than happy to post up the equations if you're interested.

Jeff

Here (http://www.geocities.com/diels12000/SwayBar.html) is some good info on just this subject.

good point, i get it now,thanks for the input

Jpete is right, the material closer to the center of the shaft sees less and less torsional stress, at the center of the bar the stress is zero, therefore the material near the middle of the bar is mostly adding weight to the system rather than any advantageous strength. A hollow bar may have to be just slightly larger in outside diameter to accomplish the same torsional strength as the solid bar but it will be a lot lighter in weight than the solid bar. Hollow bars are not junk, in fact this is true in many other places as well. Some ultra high performance crankshafts are hollow in the connecting rod journal area now there's some real intense torsion to control there! Now I know this is primarily done to reduce weight in the rotating mass but the strength/torsional issue is still there. Think of those incredibly long overhead traffic light arms that hang over the roadway, don't think they would support the weight of the material they are made out of and the weight of the traffic lights if they were solid....there are many other industrial and architectural applications as well. As jpete said it's all in the equations.
Sam

Originally posted by Sams454SS:
Jpete is right,.....
Sam Hey thanks Sam, think you could come by and tell my wife? :D

Seriously, I knew tearing my hair out in "Strengths and Props" would pay off. graemlins/thumbsup.gif

Jeff