I've never actually used stone or steel gears or rods, always skipped straight from wood to diamond before I manage to eventually claw my way into bedrock. Thus explosions from too much torque/speed are just a matter of making sure I don't screw up which way I gear.
That strategy is very heavy on the diamonds though, definitely not for everyone.
Oh, I always went straight to bedrock gears. I remember now. The coils initially had a safety and would charge up to their max, (or indefinately?) and then stop charging. The update made it so they explode if overcharged. Of course, I couldn't get to the overcharged ones before they exploded after the server update, and they all had a rather large quantity of excess energy. There was a big hole.