8mm gearbox
 

Hi, I'm looking for a new gearbox and I've seen a G&P 8mm Bearing Gearbox at a low price. But I was wondering if a 8mm gearbox will fit my G&P m4 receiver.
whats the difference betwen a 7mm and a 8mm.

thank you.

The size of the bushing used for the gears.

More to the point you should be asking "What benefits are 8mm bearing guides over regular 6mm metal bushings?".................... low fps and high rpm set up, sure, but aside from that they are largely useless and higher fps springs will wreck the bearing bushings. Add in bearing bushings aren't very friendly to some types of gear sets, if you have to force it on, expect to never get it back off, makes shimming a nightmare.

My $0.02 worth. And yes, I'm biased, have chased around too many 1mm balls due to the bearing coming apart because of springs or gear shafts.

would a.. lets say m120 spring l'be to high for this kind of gearbox.
intending of shooting at least 370 fps.
sorry for my english

I have been using 7mm and 8mm bearing bushing with M110, M120 and PDI 170%/190% spring for over a year with heavy use and both bearing bushing have not failed me yet.

I agree to the point that I've killed every set of 7mm bearings that have come my way, even the supposed best like the Kanzen... but they still take me 50,000+ rounds at 450 FPS/25 RPS to break. 8mm should be extremely robust just like how 7mm bearings are so much better than 6mm.

I just got my first 8mm G&P gearbox and it's running at 400 FPS at 30 RPS so we'll see how it goes. Unfortunately I don't play much in winter so I won't have any first hand usage experience for quite a while.

Common install problems with larger bushings is the grip hitting the bottom bearing (quick dremel/sand job on the inside of the grip fixes that), and the selector plate might need to be shaved so it doesn't get jammed on the bearing.

Get a Modify 100 spring, it'll get you around 370 with a bearing spring guide. 120 is too high for that target velocity, and is too risky as it can also get you up to 425fps at times, depending on the brand (120 is supposed to be 120 meters per second, which translates to just over 390fps). I've installed a few types of 110 springs (shoudl be close ot 360fps) and have gotten 410fps out of them at least (Madbull brand, think Guarder is the same).

Yes I had a Guarder m110 in an other aeg and it gets around 410 fps. You reccomend to add a bearing spring guide to the g&p gearbox?
And by the way thanks for your advices.

Ya, bearing spring guide lets the spring torgue when it compresses/decompresses. Also tends to add an extra 15fps as well. Work having anyways, but is likely your G&P will have one anyways.

Here's a question: Is the tappet plate still the original G&P one? If so, toss it in the trash and replace with a decent one. Modify makes a good one too. G&P AEGs all tend to have their tappet plates snap within the first thousand or few rounds, unless you've noticed already.

Yes, tappet plate is original G&P. Is a systema version 2 tappet plate would be good? Or should I order an other brand.

Systema stopped producing theirs a while ago, they're now Area 1000 tappet plates if you want one by the same company, and they're fine to use. The stock one should be fine though, the G&P ones haven't been breaking for the last 1+ years (although tons of shops still sell the older G&P's and I don't know which one you own).

If you are going with my recommendations of using Modify parts, get all that brand through Jugglez, V2 tappet plate, 100 spring, etc. as yo ulike. And the piston (even the bassic one) is amazing. All for really nice prices too. If ordering the 100 spring from Jugglez, might as well get all from there, and Modify I'm super imporessed with, high quality, predictable......... I wish Systema (and other high end brands actually) parts were as good!