I know this topic is many years old but I've recently bent two 1" diameter crankshafts on a Honda push mower because they use a steel Woodruff. The first crank bent when i hit a low stump from a bush. I had it replaced to the song of $250 parts and labor. The second I bent back straight this afternoon with a 3lb hand maul, after hitting a fist sized rock that bent the crank to a runout of 2.5mm (I was using a metric dial indicator). My hands wwre numb for 30min after using the vibrating mower. Anyway why would Honda use steel keys? Just to provide their service centers with hundreds of dollars of repair work and many angry customers? I got my shaft runout to about 0.6mm and it runs very nice now. But I'm shopping for zinc/aluminum keys right away.