After engine removal the swingarm literally folded up - the engine bolts were the only thing holding it together!!!!!
Tom- I've never seen a factory swingarm for a GY6 made from round tubing? but I'm sheltered!!!
I believe the THIN (16 gauge) rectangular tubing cracked due to stress near the holes I drilled for the fenders & welds creating a chain reaction on the rest of the tubing due to torque loads from the engine and the excessive bouncing when doing slides/donuts. I knew the stock swingarm was thin- just didn't realize how thin!!!! As I said before about which is stronger- depends on the loads and distance between the next structural component. I went to buy some rectangular tubing- the only thing they had in stock was 2" x 3" x 1/4"(way too heavy) So I'm using 1-1/2" x 1-1/2" x 3/16" square tubing for the swingarm rails (too many parts that need a flat surface). Since I just got started rebuilding it AGAIN, I'll decide as I go based off the loads I think will be apllied. I can say that every part will be at least 1/8"/12g. min. Something that we noticed soon after the fender installation was a vibration/sound frequency from the plastic at higher RPM's. I know from my construction experience that the right frequency can cause all kinds of damage to certain materials. The swingarm I made on the Spiderbox is a much heavier gauge tubing- no failures so far with the same abuse.
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