Where's the engine mass in relation to the rear axle, in front or behind? NM, see it now-- Reason i asked, it think a lot of the cracked Gy6 tails are from some of the engine mass acting as a counterweight behind the axle and working against the suspension movement. Been looking long and hard at swingarm mounts, shock points and rear axle in relation to the weight of the engine and how it acts on the suspension and swingarm. Looks like your one crack started possibly from the fender hole, the drill may have left a stress riser when it first broke through inside the tube if you went in from the "inside" of the swingarm. Likewise, maybe not from big hits, but harmonics from a lot of short, rapid suspension oscillations ... do you ride on any washboarded-out trails/roads?
Last edited by x-bird; 04-08-2012 at 06:20 PM.
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