Originally Posted by BLACKWATER204
Bushings are crap (unless your mechbox is 6mm then you really have no choice). Simple fact bearings have less rotational resistance than bushings and givin you purchuse good quality bearings (kanzen comes to mind) you shouldnt have problems with them reguardless of the load or speed of your set up. Think about the solid steel axle on your gear set, now think about the solid steel bushing. Those two pieces are creating mass amounts of friction when your gear train is moving and both (givin the material density is the same or close) are wearing out causing more and more play between axle and bushing making your gear train less stable and more prone to failure. Yes one may argue that they grease these two parts but the loading from the gear train will eventualy squeeze this lubricant out of the bushing journal and cause metal to metal contact. I am aware that there are a number of brands that produce a bushing with "lubricant grooves'' in the bushing channel but this is not really helping the situation much as there will still be metal to metal contact were the grooves are not cut in the journal ( these groves dont dispurse lubricant they just kinda trap it in 1-2 areas in the bushing journal)
If you have the option for bearings 7mm minimum, I would recomend using them.
That's a car.
You're forgetting that the ball bearings in these are TINY are prone to failure. I just sold a buddy a 9mm bearing gearbox which I trust more, because the bearings and balls themself are huge compared to 6mm ones.
I'd still recommend solid metal bushings over bearings any day.