7, 8, & 9mm bearing gearbox

Sam Fisher

Educate me please. What are the pros and cons of the various types of gearbox?

Thanks in advance.

Hope I am posting this in the right pleace Mods.

Firekitten

Essentially, (in the case of ball bearings) The larger the size of the bearing, the faster the gear axle can spin inside it. so eight millimeters is better than seven, nine better than eight, and so on, Also, with larger size, the rate of failure of the bearings falls, as the overall size of the ball bearing itself is increased. This improves the structural integrity of the all bearing and they are able to withstand a great deal more stress. (there is a LOT of stress inside a gearbox... especially latterally against the axles when under load).

Essentially, a 9mm bearing gearbox will have a higher rate of fire as the axle is more free to spin, and will perform more reliably (lower bearing fail rate) than a 7mm box.

Airsoft bearings have increased in size to improve performance essentially. Bigger in this instance, does mean better. :rolleyes:

Hope this helps

Decoy

So if that's what bearings do can you explain what benefits you get from 'shimming' a motor? I'm guessing they are used to ensure the motor doesn't move laterally so all the energy is focused in the correct axis but don't quote me on that as I am mechanically challenged!

BioHazRd

Shimming your gears properly will position them in the gearbox so they mesh together optimally with minimum lateral movement. it compensates for the tolerances in gearbox sizes by esentially adding spacers between the gear and the bearing / bushing. Too much shim and the gears will bind when the gearbox is closed, at best, the motor will have to work harder to turn the gears - at worst, your gearbox will lock up. Too little shimming and the gears may move laterally when rotating which could cause premature wear. Shimming is very much specific to your gearbox so the shim setup on one m4 for example may not be optimal on your m4. I may even suggest that shimming is something you can't be shown, bit rather something you must learn from experience.

Sam Fisher

Firekitten wrote: »

Essentially, (in the case of ball bearings) The larger the size of the bearing, the faster the gear axle can spin inside it. so eight millimeters is better than seven, nine better than eight, and so on, Also, with larger size, the rate of failure of the bearings falls, as the overall size of the ball bearing itself is increased. This improves the structural integrity of the all bearing and they are able to withstand a great deal more stress. (there is a LOT of stress inside a gearbox... especially latterally against the axles when under load).

Essentially, a 9mm bearing gearbox will have a higher rate of fire as the axle is more free to spin, and will perform more reliably (lower bearing fail rate) than a 7mm box.

Airsoft bearings have increased in size to improve performance essentially. Bigger in this instance, does mean better. :rolleyes:

Hope this helps

This sure does help, Firekitten!! However, if the bearing are bigger, even by 1mm, something else have to give because the gearbox are standard size?

So, is it worth changing a 7mm bearing gearbox to a, say, 9mm bearing just to get better performance? Does this upgrade make your AEG more reliable?

Really appreciate all the help so far from everyone responded.

Puding

bearing ca give you the best speeds possible from your gearbox, but unfortunately they have natural weakness and in essence, what makes them great for speed also makes the brittle , its the added strength the larger sizes add to bearings, with large diameters the flanges can be stronger and stand up to more abuse within the gearbox, its not really the rotational force that is the problem more the mis align meant of gears within the gearbox putting undue pressure unevenly on the bearing, this can happen if the apertures are not aligned correctly in gearboxes for example, correct shimming has so many benefits for a gearbox, increased rof better battery life less sound etc etc but its definitely the alignment that has caused me (note as i said this is my own personal experience and nothing more ) the greatest problems in the passed with bearings so much so that i just use bushings

so for speed bigger is better



but for 9 out of 10 people who just want to play and are not looking to do weird and wonderful things with there gearbox, just want to shoot a normal rof at 1j and not have to constantly be working on there gearbox 7mm bushing are fine

its very easy to go made on upgrades and to be honest for most people use there completely pointless and a waist of money, i've seen people going out and spending 200euros + on branded internal parts for a gearbox where there stock cyma shoot just as well

Puding

This sure does help, Firekitten!! However, if the bearing are bigger, even by 1mm, something else have to give because the gearbox are standard size?

yes gearbox are a set size, but go even up to 9mm apertures for bushing/bearings has little structural impact on the gearbox walls, the stress exerted on the walls within the gearbox does not cause a problem

your greatest concern with any high speed set up is the strain on the front end, an issue you commonly see with kwa, is hairline cracks developing and the front end breaking off

on this point 'upgraded gearbox' upgrade in completely the wrong areas, normal adding material to the ass end of the gearbox, have yet to see the new kwa gearbox that are meant to be correctly reinforced

Firekitten

Sam Fisher wrote: »

This sure does help, Firekitten!! However, if the bearing are bigger, even by 1mm, something else have to give because the gearbox are standard size?

So, is it worth changing a 7mm bearing gearbox to a, say, 9mm bearing just to get better performance? Does this upgrade make your AEG more reliable?

Really appreciate all the help so far from everyone responded.

MMmmm, Its not an 'upgrade' on its own. To use 8 or 9 mm bearings, if your gun takes 6 or 7, one requires a new gearbox shell, with the correct sized holes for the new bearings. Obviously one that fits a 6mm wont take 9! You can buy new shells from most of the HK retailers, and its not a gun... so not really a biggie with customs, if it even hits them.

a 7 to 9 upgrade will make the bearings more reliable, and run more smoothly. However is the difference discernable? Possibly not, possibly so, is it worth it for reliability? yup. Again its a game of pennies.

Sam Fisher

Puding wrote: »

the greatest problems in the passed with bearings so much so that i just use bushings

More questions, if you don't mind...

What is the difference between bushings and bearings? (no funny answers please:P)

Puding

bearings http://en.wikipedia.org/wiki/Bearing_(mechanical)

bushings http://en.wikipedia.org/wiki/Bushing

Masada

In airsoft we refer to the solid ones as bushings and the bearing ones as bearings as puding said, but they are both just a type of bushing. a solid one and a bearing one. The bearing having a rotating core for the gear axels and the solids are exactly that, solid.

I typically use bearings, mostly 7mm without any problems.
The only bearing problem ive had was with 6mm bearings which are too small and under too much load for their design.

One big benefit to bearings and one of the main reasons i used them is because they reduce gearbox noise and are really smooth. solids arn't as quiet but are stronger and less likely to fail. At 1J though its unlikely you'll have bearing problems unless they are either shit bearings or not installed/shimmed correctly.

Sam Fisher

Thanks Masada, and welcome back!

Firekitten

Post deleted, Puding is self diagnosed mad, thus the post is irelevant

Puding

I may be confused with your words here Puding... but theres two 'bearings' there and one 'bushing' Somehow i have this idea you're saying the smaller bearing is a 'combo'?

ignore me im going mad and going to get some sleep :rolleyes: