Crunk, Hot racing has hardened spur gears and pinion gears. They are available, you just have to search the web for them. Robinson Racing and Kimbrough Racing are two other places you can order harden steel spurs and pinions. If you go to a harden spur you will also have to go to a harden pinion. You don't want to mix a harden spur with a mild steel pinion and vise versa.
I have two Amp Crushs, one blue and the orange one. Both have been upgraded from suspension, to night running, to brushless. I have recently started using the Hobbywing Easy Run 4000kv brushess motors and have absolutely no problems. Both trucks run on Gen Ace 3S 7000 mAh (7 amps) batteries. I also have the first generation ECX Amp which is also upgraded as above. These trucks are awesome when they are upgraded. Out of the 36 rc's that i have they are my favorite. Here are some pictures of my blue Crush and my Amp. Happy Rc'ing to you and use your imagination and ideas.
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