I have tried a 12 point, just rounded the nut shoulders, I tried a 1/2 drive imapct with a claimed 500 ft pounds and a 6 point impact socket, still no luck. At least its not rounding off the shoulders anymore. I tried securing the sprocket with the socket trick described here, still no luck. Dang, looks like I am cutting this thing off, but before I do, any one have other ideas? Any guesses as to how much torque one needs to get this damn thing off? It sure as @%$#$@ has a lot more than 90 ft lbs on it originally. Yes I have flattened the cup washer, I am turning counter clockwise, and generally frustrated.