G&P Gearbox Woes... Any help please?

[beta08]

Hey guys.

 

I have a G&P M4 (purchased here) that is having some pretty bad issues. I'll try to give you a general history of the weapon as it may help.

 

1. Purchased the rifle from WGC

2. Swapped the upper for another G&P upper with a different front end

3. Went to 1 game with it, it only chrono-ed 250

4. Stripped the pinion gear at said game, replaced it with a Guarder Steel pinion

5. Gun functioned for a short time afterward, still chrono-ing low, then started "jamming".

 

Perhaps a better word would be "locking up." When I pop a battery in and pull the trigger, I will get 1-3 shots off before the gearbox locks up. All I will hear is a clicking indicating that the motor is trying but nothing is happening. I then either release the ARL or take the gearbox apart, reassemble, try again and get the same results. Also worth mentioning is that when I took the weapon apart I was (unpleasantly) surprised to find one of G&P's crappy old gearboxes with black plastic bushings and not the new 8mm bearing gearbox I was expecting. There was close to zero compression in the cylinder.

 

Also worth mentioning is that I have done a bit of investigative work myself. My buddy has a perfectly running G&P M4 with the new 8mm gearbox, so we swapped uppers and lowers. These were my findings:

 

1. With his upper and my lower, it still only chrono-ed at around 250. I'm thinking compression issues in the gearbox.

 

2. With his lower and my upper, same results. Did I get a lemon hop-up as well?

 

So basically, my question is: What is the problem? I know for a fact that the compression sucks, and the hop up may be a lemon as well. However, I have no clue as to what the whole locking up problem is about.

 

This all seems really strange to me and I am considering just taking the entire thing and throwing it out the window.

 

Any help on this matter would be GREATLY appreciated.

[hwagan]

Also worth mentioning is that when I took the weapon apart I was (unpleasantly) surprised to find one of G&P's crappy old gearboxes with black plastic bushings and not the new 8mm bearing gearbox I was expecting. There was close to zero compression in the cylinder.

 

 

See, I have a feeling you may have been slightly scammed by WGC here. Well, maybe not scammed, but slightly mis-led. I'm almost entirely certain that G&P have never done plastic bushings; Hell, they were 7mm bearings in 2007, so it seems unlikely they've decided to do plastic bushing gearboxes inbetween 7 and 8mm bearings.

 

There's also the fact that WGC, who like most retailers usually specify 'G&P M120 8mm bearing gearbox'; in this case just states 'V2 gearbox'. They also list the FPS as 250-270, which is what you're getting. Lastly, $196 is a fair bit less than the usual cost of a rear wired, crane-stocked G&P M4.

 

My money is on that's not a G&P gearbox; It sounds like instead WGC have had a pile of G&P externals from custom guns or something, and fitted random sportline gearboxes of some type in the bodies and sold them as G&P's. I'd get onto WGC and ask them what the hell's going on, because that definitely doesn't sound like a G&P gearbox to me.

 

*edit* Also, M120 motor attached to sub-standard gearbox might be a reason for the repeated lockups?

[league 4]

It's one of their "sportline" M4's... I remember Redwolf having some up but IIRC they were listed as 6mm bushings, didn't know they were plastic though. But for the price they're asking for that and the description, sounds like a sportline one to me. Have you tried a thicker bucking to help compression? Is the hopup the same as the other G&P's (black dials)? What other internals are different? A picture of the gearbox opened up would be appreciated.

[beta08]

 

 

See, I have a feeling you may have been slightly scammed by WGC here. Well, maybe not scammed, but slightly mis-led. I'm almost entirely certain that G&P have never done plastic bushings; Hell, they were 7mm bearings in 2007, so it seems unlikely they've decided to do plastic bushing gearboxes inbetween 7 and 8mm bearings.

 

There's also the fact that WGC, who like most retailers usually specify 'G&P M120 8mm bearing gearbox'; in this case just states 'V2 gearbox'. They also list the FPS as 250-270, which is what you're getting. Lastly, $196 is a fair bit less than the usual cost of a rear wired, crane-stocked G&P M4.

 

My money is on that's not a G&P gearbox; It sounds like instead WGC have had a pile of G&P externals from custom guns or something, and fitted random sportline gearboxes of some type in the bodies and sold them as G&P's. I'd get onto WGC and ask them what the hell's going on, because that definitely doesn't sound like a G&P gearbox to me.

 

*edit* Also, M120 motor attached to sub-standard gearbox might be a reason for the repeated lockups?

See, for the price I paid, I was perfectly content with just paying for the externals at that point since they are the same as any other G&P and worth over what I paid anyways. I believe the gearbox is in fact G&P as the gears have G&P stamped on them.

 

It's one of their "sportline" M4's... I remember Redwolf having some up but IIRC they were listed as 6mm bushings, didn't know they were plastic though. But for the price they're asking for that and the description, sounds like a sportline one to me. Have you tried a thicker bucking to help compression? Is the hopup the same as the other G&P's (black dials)? What other internals are different? A picture of the gearbox opened up would be appreciated.

 

Ah yes, I'd forgotten about those completely. The hop up is identical to the newer G&P's with the black controls. The hop up that is jamming is fitted with a Prommy Red bucking, which is very well the problem. The other upper with the less-than-expected FPS is just a stock G&P bucking. At this point though, I'm 100% sure that you're right about it being a sportline gearbox. That's the only difference, right (the gearbox)? The externals seem like every other G&P I've owned which is excellent.

 

So pretty much, I'm considering just grabbing this and some sort of new hop-up and calling it good to go. What do you guys think?

 

EDIT: This is the guy in my G&P currently. Avoid like the plague.

[BaggyPants]

Yes to the G&P 8mm bearing gearbox. Bloody superb! I wouldn't change the hop unit, because G&P make one of the best, just the rubber bucking. Perhaps with a Marui rubber bucking, as they seem to get good reviews all the time.

[beta08]

Agreed, I can't say enough good things about their new 8mm gearboxes (I have owned them before). The only reason I am considering changing out the hop up is that both of mine can't seem to get a good seal on my friend's perfectly working G&P M4. Again though, do you think this is a hop up issue or just the bucking? Those are cheap and I could get 3 or 4 different ones just to experiment with I suppose. The Prommy Hard type one I have now is doing nothing but causing jams.

[BaggyPants]

As you say, buckings are fairly cheap, so I'd try a few different ones first before going the whole hog and replacing the complete unit. I still have the standard G&P bucking in mine, because it works fine for me, but it seems they're pretty hit and miss as to wether you get a good one or not. When it finally wears or tears, I'll be trying a TM bucking in it before anything else.

[hwagan]

See, for the price I paid, I was perfectly content with just paying for the externals at that point since they are the same as any other G&P and worth over what I paid anyways. I believe the gearbox is in fact G&P as the gears have G&P stamped on them.

 

 

Ha, makes 2 of us who forgot the sportline gearboxes! I think G&P even did an ABS version of them for a short while, but I don't think many ever sold.

 

Agreed, I can't say enough good things about their new 8mm gearboxes (I have owned them before). The only reason I am considering changing out the hop up is that both of mine can't seem to get a good seal on my friend's perfectly working G&P M4. Again though, do you think this is a hop up issue or just the bucking? Those are cheap and I could get 3 or 4 different ones just to experiment with I suppose. The Prommy Hard type one I have now is doing nothing but causing jams.

 

Unless there's any obvious deformities or flaws in the hop unit itself, I'd go with changing the bucking - Like everyone else is saying, experiment with a few different ones. I've had good results out of G&P's with stock TM, stock G&P (sometimes), Madbull blue, Guarder clear and King Arms - Generally *frootcagio* about with several different nub and bucking combos can increase your performance more than anything else I've ever done to an AEG. If the buckings don't fix the issue, buy a new hop, then you can still try out all the bucking combos. Money is on the rubber being at fault though.

[league 4]

I wouldn't bother with the new gearbox because 99% of the time, it's cheaper to replace the individual parts inside of it instead.... I also wouldn't want to deal with another set of G&P gears. If you do want a new complete gearbox, I HIGHLY recommend this one:

 

http://www.shootercbgear.com/product_info.php?products_id=2759&osCsid=5voa3264nj7m3np5n03c6sqpb2

 

Over a G&P one (and this is coming from a G&P fanboy....).

[beta08]

Huh, Lonex you say... I'm assuming you've had some pretty good experience with them?

[league 4]

440FPS, 27rps, for over a year/at least 70k shots with lonex everything except for the spring, motor, gearbox shell, and bearings. NO wear on anything, and it hasn't given me a single problem. I also use a bravo (US rebrand for lonex parts) tightbore and hopup chamber, both have given me better results than Prometheus parts that I used to have.

[beta08]

Wow, that's actually really impressive. It's a bit more expensive than the G&P gearbox but if it's as good as you say it is it'd definitely be worth it. Thanks for the help guys!