I also ordered the 52T hardened steel spur from Golden Horizons. As jhautz talked about it will add some needed space between the battery and the motor. I must say the metal on metal pinion/spur setup is really noisy and vibrates everything. The sound is pretty harsh. Kershaw sells some 5mm mod 1 delrin pinions with brass centers that might be worth trying. I just don't know how they would hold up though, probably not last long.