all gear drives are a bad idea... why do you think professional racers run chain drives still.... no matter the quality, you're still adding harmonics to the rolling assembly.... its like running a motor without it being balanced... it'll run, might even womp hard.... but its gonna wear out fast.... i went thru 2 cranks with my mustang before i researched the problem more, kept spinning bearings, i line honed, took it to machine shops for second opinions, and then finally i got the right guy that asked me if i was running a gear drive