6mm v 7mm gearbox

[Ares]

so im left to assume that 7 is better than 6, but are there any down sides? i've used both, but cant tell any major difference.

G&P AEG's, which are they built with? would it be wise to use a CA rifle with a 7mm box over a G&P rifle IF the GP uses 6mm gearboxes? any GP rifles have 7mm boxes?

[babybackribs]

I took the gearbox out of my G&P and it has 7mm bearings.  All G&P guns come with 7mm bearings.

[Ares]

fantastic! that finalized my decision.

but as far as the real advantages, is it simply gearbox integrity? longevity? are there any adverse effects like increased maintenance? does that add any variables in performance that otherwise don't effect a 6mm gearbox? I try not to start new threads, but i cant find any data thats this specific, so i thought i'd probe around here

[babybackribs]

Most of the time it depends on the setup.  6mm gearboxes generally have bushings and are low ROF.  7mm gearboxes usually have bearings that are used for higher ROF and durability.  8mm gearboxes are used for high ROF and longevity.  Basically, it just comes down to personal preference.

[BATMAN]

Speaking from experience, here's what I can tell you about bushings:

The difference between 6mm and 7mm bushings is just the ability to absorb energy over a larger surface area, resulting in theoretically longer life-time, HOWEVER, most metal busings will wear out due to friction with the gears long before they break due to stress, so, really a 7mm gearbox doesn't give you any real advantage unless you're using ball-bearing bushings.  

The idea behind ball-bearing bushings is to nearly eliminate the friction caused by the gears, and to transfer energy to a series of ball bearings, instead of a machined piece of metal.  Because of these factors, well-designed ball-bearing bushings will have substantial longevity, as well as let your gears spin more freely, often resulting in a higher rate of fire.  (It is important to note that precise shimming is even MORE important for bearings than it is for standard bushings.)  Plastic bushings also do a good job of reducing friction and flexing to the torque of the gears, but ONLY under low-stress conditions.  That's why it's important to consider upgrading your bushings when raising the the tension of your spring significantly.

NEVER use 6mm ball-bearing bushings.  They are a waste of your money;  I've never had a set last longer than a month.  They're just too weak to hold up to any amount of stress.  7mm, however, are much more solid, and will last much, much longer, especially if the gears are shimmed properly.  8mm, as you can imagine, are even stronger, but they can be harder to come by, and are certainly more expensive.  In my opinion, 7mm or 8mm ball-bearing bushings are the best choice for most AEG's.  

Keep in mind, there are SOME guns that have parts that fit around the gearbox very tightly, (such as selectors, or a selector plate) that absolutely WILL NOT FIT to 7mm or 8mm bushings, without modification.  Examine those things before upgrading.  Another important note is that if you are using solid metal bushings, make sure they fit tightly into their holes in the gearbox.  I have seen dozens of gearboxes completely destroyed because the metal bushings actually bore out the holes in the gearbox from spinning too freely.

I'm not sure exactly why I just took the time to write all that when I have finals to study for, but I really hope all that information helps.   Let me know if you have any questions.
-BATMAN

[Ares]

it helped for sure, put it all in perspective for me, thanks. I'll look into the ball bearing bushings for the 7mm box, even though im sure that they require special attention, no matter, im willing to give the extra attention to increase efficiency and longevity.