differnce of differnt milimeter bearings?

[Gills]

Hay my good friends, It has always puzzled me, what is the differnce between different milimeter berings?
I heard from somewhere that bigger berings reduce the stress that pertrudes on the gear box.
I've also heard stories of people putting differnt size berings in thier gearbox to reduce the stress on thier gears, is there any rule of thumb for bearings?

While looking at gun porn, i noticed that new 9mm bearings have came out, does bearing size make an impact on the gearbox?
your thoughts please.

[KileyHAZ]

Spell checker is your friend...

Bigger bearings means more heat dissipation and less friction. A 6mm bearing will only support up to a certain number of RPMs before they bind up, the 7mm supports more, and so on...

[AxisOfOil]

As usual, Kiley is, for all intents and purposes, spot on...just missing the word 'density' in his friction statements.

The larger bearings technically have MORE friction and MORE parasitic drag, but significantly lower friction per area of the bearing, and therefore wear down less.

They're more durable, are less likely to create stress fractures around your bearings in the gearbox (has anyone heard of this actually happening to a metal gearbox?), and give you the option of saying "I have a 9mm gearbox!!!"

[clayton]

that explains why the m249 has 8mm bearings.