How thick is to thick?

[Corban_White]

I understand that, and I probably shouldn't have said anything about wall thickness--but with the diameter of a typical driveshaft, if it's a spring steel trying to be a torsion bar, we're still going to see incredibly minimal twist, I'm thinking. Just too much spring rate at the large diameter to really matter.

Plus, if there were much deflection at all, they'd fail at/near the weld consistently, since the heat-treatment would be ruined right there.

Sorry, I commented out of context. I was not referring to driveshafts or the special material it has been said they are made of as I know little about them. I was simply responding to a couple of materials properties questions/statements that I DID know the answer to.:greg:

 

[Caleb]

After thinking about this, Since DOM is a process and not a material, it could be that they all use DOM tubing, but it may be some special tubing material as well. I'm curious what the name of this special tubing is (the internet doesn't seem to know ). All tubing, pipe, etc will have some deflection, like Carl said though, it's such a short piece of tubing that it's not going to be noticeable.

 

[Chevycrew]

http://www.wipo.int/pctdb/en/wo.jsp?wo=2004071686

A method of manufacturing a seamless steel tube for a drive shaft and a method of manufacturing the seamless steel tube, wherein a hollow member for the drive shaft having excellent fatigue strength and suitable for reducing the weight of a vehicle body can be manufactured by applying a facilitated inner surface cutting and the subsequent cold reduction to a steel tube hot-drawn by a Mannesmann tube manufacturing method to specify the recessed part depth (d), surface roughness (Ra), and recessed part inlet width (w) of recessed and protruded parts forming the inner surface of the steel tube or, in the same manner, to specify the recessed part depth (d), Vickers hardness (Hv) of the inner surface layer, and recessed part inlet width (w) of the recessed and protruded parts. Since the drive shaft for car can be efficiently manufactured at low production cost, the effect thereof can be industrially increased



But that doesnt mean I know what it means...

 

[Chevycrew]

I googled driveshaft tube steel and got a few hits along with suppliers

 

[Craig S]

Drive shafts all have to be welded. If the steel had twist or flex like a sway bar or leaf spring it could not be reliably welded (high carbon steel). Any flex must come from using a thinner wall (weaker shaft). I want my drive shafts made from a DOM mild steel material that won't twist or flex from rotation (1020/1026 steel, see http://www.teamtubellc.com/products/round-tubing-products/mechanical-tubing/driveline-tubing.aspx). Thick is good for rock crawling. Thin light shafts are better for transferring horsepower. Stick with the thick stuff for off road vehicles. I recommend Tom's rock and roll for off road only. The next best is to use a long heavy splined section. By this I mean that instead of the 6" to 12" splines seen on most shafts I use about 24" (depending on shaft length). This way when my drive shaft is hitting a rock with the vehicle weight on it, it won't bend because I have a solid shaft in the middle that only lets it flex a little instead of kinking. Small OD diameter shafts are best for this with thick tubing say.120 or thicker. That gives the solid spline section a closer tolerance and less prone to bending. I hope this makes sense. I have never had a failure from either style of shaft, but the rock & roll is by far the best and probably the last shaft you will ever buy for a buggy.