To all AEG Gear Heads (Gun Doctors)

[HaZarD SFD]

This should be interesting.

What is the difference and why between Bevel Gears?
Also troubleshoot the problem below if related.

Rules:
1. Dont post in here at all if you dont know what your talking about.
2. Please have experience installing gears in an AEG
3. Gun doctors are more than welcome to post

Reason for this question is! I have a G&G M14 (dont knock it as its a kickass rifle when stock)
it was upgraded and Star Gears were put in. The stock G&G gears have a 5* bevel gear as per
the Star Gears have a 4*. Now the rifle shoots a good 200ft but sometimes it shoots 100ft, 5ft,
5ft, 10ft, 150ft, 200ft. Verry erratic. and sometimes lower velocity. It has a G&P 120 spring,
Prom Spring guide, King Arms 7mm Bearing Bushings.

[Skruface]

Firstly, the only difference in the bevel gear's number of "bevel teeth" (5 vs 4 vs 2 on old Marui gearsets) is where, during the gearset's cycle, that the anti-reversal latch catches. The more "bevel teeth" your gearset has, the faster the anti-reversal latch will catch, and this allows for a somewhat faster followup shot when shooting in semi-auto. However, I don't have any benchtests to prove this - theorhetically, that's how it works, but I doubt it makes a real huge difference in a real game situation - we're talking fractions of a second of difference.

Now, that aside, I doubt the gears are the issue with your inconsistent velocity. It sounds more like a hopup or airseal related issue to me.

[CDN_Stalker]

I'm the one that did the work on his gun, and if you think about it, something is most likely causing the nozzle to be in different positions when the piston is released. Only things that were replaced was the spring, gears and spring guide, ok, the bushings too. But the airseal issue wouldn't be that sporatic, it'd be more consistant. The gun has had shots over 400fps, but others the BB could be thrown by hand farther. So if the nozzle isn't fully in the breech, then that would be the airseal problem, but only once in a while.

I suggested he post the question on here because we're both baffled, and the only difference noticed in a change to the gun was the number of catches on the new bevel gear compared to the stock one. Only other thing that comes to mind is the sector gear, maybe the relationship between it and where it rests on the sector gear axle has changed with the gear swap.

[Cushak]

Is it possible to swap back in the stock Bevel gear and see what it does?

[HaZarD SFD]

Also when it does that once in a while full auto burst of like 2-5 rounds it will
all of a sudden go shooting 200ft untill you start to pull the trigger faster in which it feels as if its only shooting like 100fps.. it fires at a lower power if you pull the trigger at a faster pace.. then it might full auto burst again then its the 200ft, 10ft, 5ft, 5ft, 5ft problem all over again.

Stock gears are going back in.

[Cushak]

Originally Posted by HaZarD SFD

Also when it does that once in a while full auto burst of like 2-5 rounds it will
all of a sudden go shooting 200ft untill you start to pull the trigger faster in which it feels as if its only shooting like 100fps.. it fires at a lower power if you pull the trigger at a faster pace.. then it might full auto burst again then its the 200ft, 10ft, 5ft, 5ft, 5ft problem all over again.

Stock gears are going back in.

Originally Posted by Skruface

and this allows for a somewhat faster followup shot when shooting in semi-auto.

Make no mistake, I'm not gun doctor, but based on Skruface's description of the bevel gear, and how this problem "fixes" itself if you do a full auto burst, I wouldn't be surprised if it was the bevel gear.

[HaZarD SFD]

other tiny issue is without the RAS on it shoots nice and straight.. but with it on
it shoots to the right after 100ft.. hard curve.. IMHO tension on barrel and body
from the RAS fitting so tight.. gunna crack out the dremel

[HellRanger]

Hopup chocking the rounds?
When you go back to a longer range is the hopup still set properly or is it off (too low)?
If the hopup chocks a round in the chamber or a rounds gets stuck in the barrel this will happen. Does this only happen in full-auto or semi only?

[HaZarD SFD]

Ok with Rifle assembled and RAS not installed it shoots fine and dandy 200ft
Now with the Ras Installed it shoots 200ft but after 100-150ft they veer right.

Hopup doesnt move at all when set. Its an AUG style hopup in a G&G.. damn
nice and easy to set too.

[ILLusion]

The position at which the anti-reversal latch catches on should not affect the chambering of the BB in any way. The bevel gear starts the cycle, and regardless of where it gets caught by the latch, the nozzle will always chamber at the end of the cycle.

I can't see how changing the bevel gear can affect velocity in any way.

Skruface has it right - the number of catches only allows for faster pickup time, as the bevel gear can catch a bit later in the cycle during gear overturn. It allows for a noticeably faster semi-auto fire reaction time.

[HaZarD SFD]

Im not blaming this on velocity im asking why it shoots the way it is and what the differences between the gears might or might not cause it. Also it fires fine its just the distances that it shoots at are erratic. every shot is nice and hard but sometimes it just dont spit em out hard enough.

[Spa]

What are those gears in the top picture?

But on to the topic:P
I used to have a problem like yours with an AEG of mine. Check if the cylinder and the piston head if they are actually creating a perfect seal for air compression. If its not and the O ring on the piston head is actually getting stuck stucking to the piston head, sometimes it could be a reason for FPS variation. You can check this by putting the nozzle on the cylinder head and putting your finger on it to block the air flow and then you start pumping the piston to see if the air is actually holding the piston back due to air pressure. If its not, you might have to clean you piston head and take out some grease so it doesnt stick and this will help the Oring expand to make a better seal in the cylinder.

good luck:P

[mcguyver]

The trouble encountered with gear compatability usually begins and ends with the sector gear. The size of the tappet nub and it's position on the gear, coupled with the profile of the tappet is what pulls the tappet back at precisely the right time. This is what "times" your nozzle engagement. This can be altered by changing the tappet, the sector gear or by addition of aftermarket clips to the tappet nub. Small changes is size or positon of the nub on a different sector gear can and will have a big impact on the engagement of the nozzle.

This is why companies like King Arms makes then, and why changing tappets to a different brand can have differing effects.

If you carefully compare the G&G sector gear to the Star gear, and paya close attention to the precise size and position of the tappet nub, you may find there are differences there that will explain your problem.

[ILLusion]

Originally Posted by Spa

What are those gears in the top picture?

Phoenix high protection gears.

[Spa]

protection from what Illusion? lol.