Gearbox Upgrade

[Casey]

Hi all,

My SRC M4 gearbox has had it. To get it fixed will cost nearly as much as a replacement one. (Buy the time I pay for postage there and back) So i was thinking about looking into another make gearbox, only trouble is, none of the gearbox specifications give you a rough FPS.

I would be looking for something that could offer a better rate of fire and maybe some extra distance, I already have two brand new hopup bucking rubbers that have not been used plus a madbull tight bore barrel. I was not able to get the FPS checked with these upgrades due to the gearbox packing in.

Do you think it would be worth while getting a "better branded gearbox" or just buy the straight swap replacement? I would like to keep the cost to around the £100 mark or less

 

[Airsoft-Ed]

I'd just replace the gearbox with the one you had, personally. Buying a better branded one won't offer you any advantages really. It might be built using better materials but the performance difference it would make would be too small to even notice.

If you want more range you want a stronger spring + tightbore barrel + upgrade hop rubber/hop unit. All the gearbox can really make better is the consistency of your shots by making the spring behave the same every time you fire, ensuring that the fps doesn't jump about much from shot to shot and you could upgrade/tune a cheap gearbox to do that for much less money than buying a better branded one.

My 2 pence.

The reason it doesn't tell you what fps a gearbox will put out when you're looking at buying one, is because no gearbox can offer any fps at all without being coupled to a barrel and hop unit - A gun.

If it tells you the spring that it comes with then you could make a rough guess though. An M100 or an SP100 spring is named so because it propels .20g BBs at roughly 100 metres per second, which is around 330fps. However, with a tightbore you could expect this to jump up by about 20fps. So M100 with your set up = 350fps or there abouts.

 

[sl1k]

Airsoft-Ed has basically touched on the main points. In a gearbox, there are 2 main aspects, the drive train and air seal components. The drivetrain consists of the motor, pulling the gears, that pull your piston back onto the spring. So the more tension your spring as, the harder the pistonhead will compress the air into your cylinder, releasing it through the nozzle behind the bb. So as Airsoft-Ed said, your springs determine the velocity. However, how much actual velocity you get depends on how good your air seal is, determined by the quality of your piston head, cylinder, cylinder head, air nozzle, and a tight fit hop unit with a tight fit rubber bucking. You can increase range by adding a stronger spring, but range and effective range are 2 different things. TM guns come with very low fps, but shoot further than any chinese made gun shooting 400+ fps. That's because of their hop unit design and how well their air is sealed, as well as how well the backspin is applied to the bb as it enters the barrel.

So as you can imagine, designer labels in airsoft don't mean much. Every company has good and bad products. As for a good value drop in gearbox, I can recommend JG, cheap and a solid drivetrain. If you want something a little more higher end, than guarder and lonex make fantastic gearboxes too. I think a guarder one will set you close enough to £100 though.

Note: Springs that are named with an "S" as opposed to the usual "M", tend to shoot one grade above their actual number. Example, my modify s100 spring shoots 385fps solely with air seal mods. So yeah, way over the expected 330fps.