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Gearbox Upgrading

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My gun uses a v2 gearbox with plastic bushing. I'm planning on upgrading it to 500 fps (0.2g). My questions are:


1. What type of gearbox shell should I get that can handle 500 - 550 fps?


2. If I get a SP150/SP170 spring, what other gearbox internals should I Upgrade?


I've read a guide here that says "..the Cylinder, air nozzle and Cylinder head are not really upgradeable stuff, Some brand migh be a little better than the other". Is this true?

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1st, what is your gun? most likely, the gearbox shell is strong enough for the spring of your choosing.


2nd an SP150 spring will put you over the 500fps mark. I would suggest an SP140 instead. An SP170 will put you WAY over 500fps, it should put you a little over 600fps I believe.


The cylinder, cylinder head, and air nozzle are upgradeable in most guns. But I don't know what gun you have, so I can't tell you for sure if it's upgradeable or not.

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Its like Star said...we need to know what gun you have so we can tell you what parts should be replaced and what would be wasting your money.


Though in general....


Most stock gearboxes that you find in AEGs can take a high fps if you do the correct mods: Sorbo and Radiusing the GB will preserve its life. Or you can buy an Ajax STS if its a V2.


If you are getting a Spring to shoot 500-550, but you mentioned you wanted 500 with 0.20g...I would go with an SP130, it should put you really close.


With the good compression my DMRs get, I got 530fps on a Guarder SP140 and on my PSG-1 Guarder SP150 I got 551 fps (using 0.20g though it was a used spring too)


So basically a SP140 should be 520-530ish and an Sp150 should be 550-560ish (brand new made by guarder using 0.20g with good compression)


Lets see, to get all the fps out of your spring you can, hit the Compression areas hard: a new 14# O ring (found at your local hardware store) stretch it using a match lighter....ahhh...we have a guide section for all this. In the Upgrades section of the forum. Look at the top of the stickied threads and you will see a Link to the DIY compression and mechanical mods that you NEED to do :)


I would grab a Ball Bearing Spring guide for that FPS.


You could get a metal tooth piston but as long as you correct AOE, most stock pistons should be fine.


I suggest a ported polycarb piston head (I like to use Prometheus but JG stock piston heads are great too)


For a budget CH, grab SHS (red) and same with the Air nozzle (for a tighter seal) again...DIY compression mods here.


Buy a full cylinder, Element/Deep Fire/ Systema any aftermarket full cylinder(non ported) is fine, remember the DIY mods (polishing)


A standard 18:1 gearset is fine (the stock one)


A HT (high torque) motor. I prefer G&P motors, the M160 is VERY good. Then you have the M170 which is basically the torque of the M160 with the speed of the M120. Then you have the M180 which rivals the budget JG blue and Red torque motors if not better.


Which brings me to the point where I say, a lot of techs now, recommend using the clone motors (like JG, SHS, Element, etc..) as they are cheaper and they say they perform better than the name brands. I still prefer my G&P torque motors myself though but if you are on a budget or would simply like to, grab an SHS/JG blue or red/Guarder/Element Torque motor (long type).


Grab Modify Bushings (the size in mm should be designated by the brand of gearbox).


Shims! You can't ever go wrong with having shims! :) I love Systema shims but they should all do the same thing in theory.


I am going to let you digest this and respond with something eloquent! xD


Good luck friend!


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Make sure you do all of the gearbox-specific tweaks and mods from the guides you see sticky'd in this forum. They will keep you from breaking parts right and left. With harder springs, all components of your gearbox will take much more abuse. The biggest thing that often gets overlooked is correcting the AOE. Use sorbo and/or plastic spacers to make sure the sector gear picks up exactly vertically with the pickup tooth on the piston, and be sure to shave the second and possibly third teeth.


Sorbo will help reduce the impact of the piston on the gearbox shell. This will help keep it from cracking if it's a V2. Same with radiusing the gearbox- you will DRASTICALLY reduce the stress concentration on those corners.


The cheap mods that are labor-intensive can be intimidating sometimes, but they can help more than just throwing parts at the gun until it gets to the FPS you're looking for.

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