You really do not have a clue how to work on those hubs do you? This isn't the first time you've mentioned you've had problems. Freecoasters in my experience typically do not spin free the same way a front hub does. They look as if they spin "slower" but they really don't when you ride them.
Front vs Rear: GEEZE. look at at the internals in you rear hub and chain tension causes issues too.
How the heck are you breaking your driver teeth? You riding street on it? Chain tension?