I’ve refined my safety cage a bit and done some more research into safety cages used in racing. I found a kit that featured 1.75″ tubing with .135″ thick walls. Running that through the online weight calculator I’d found, that comes out to 2.133 lb/ft. I also did a calculation on 3/4″ tubing of the same wall thickness for use in cross ties and such. Figuring out the length of the tubing in this design, I was able to do some weight calculations:
This is all obviously napkin math, but the result is pretty surprising. If I use the 1-3/4″ tubing for the main structural hoops, then tie it all together with 3/4″ tubing, my entire safety cage and main chassis would only weigh about 100 lbs 130 lbs. This doesn’t include some sub-frame pieces and none of the front suspension components, but still, that puts me well on my way, I think, toward making my < 600 lb design criteria.
Those numbers look great. Would you mind adding the link/s that you used in figuring out what size/thickness tubing to use for the safety cage? .134 wall is thicker than I recall anyone using for rock crawler offroad safety cages. They usually go up to .120 I think. But they also do a lot of backyard engineering too so I wouldn’t be surprised if you found a more authoritative resource. Either way, 100lbs (ballpark) is a great number.
The kit I found was here and upon looking at it again, I’m further encouraged that they only want $165 for it. That means that if I find a good steel supplier, the materials shouldn’t cost much at all if I’m going to cut, bend and weld them all myself. What’s super encouraging is that according to this supplier, this .134 kit “exceed the requirements of the NHRA and IHRA.”
Looks like I suck at math. That total should be 128.3 lbs. Still not bad though.