G&G L85A2 semi auto issue

defenderdude

Just wonder if anyone has come across an issue with the G&G L85A2 -
where when firing in semi-auto; it fires twice.
Then next shot wont fire,(like it half cycles the piston) then fires twice again with the next shot and so on...

Fires ok in full auto.

Any advice / experience with this problem before?

TIA.:)
Aidan.

defenderdude

Decided to pop the gearbox out - really easy to work with (so far)
Removed a small cover on the switch contacts and I think I've found the culprit - badly burnt contacts.

I'm guessing I need to replace these (as opposed to just clean up - as they look nicely fried).

Is this a good case for a mosfet addition?

Any advice appreciated.



Some not very good pics of the contacts...

Masada

Howya aido.,

yeah the contacts issue is a common culprit., as if by luck though, I think there's a new trigger contact set for one on my desk, will check for ya on tue.,:)

defenderdude

Thanks Richie:)
Cleaned them up and stuck em back together just to check if it would work as a temp fix for tomorrow but alas not.
I'm thinking there's something else - either broken or worn in the gb that's adding to/causing the problem. There's a lever for releasing the spring which is connected to what seems to be (without opening the lower gearbox) an anti-reversal latch. I'm wondering if it's spring loaded and if the spring is broken or something...

More investigation...:rolleyes::D

Masada

from what i remember (and its been a while for one of these) theres a little catch that engages with the cut off lever under that trigger block. thats what causes the issue in most cases.

defenderdude

Can anyone tell me if it's ok to use a different piston head to the stock G&G one? I see G&G seem to sell one specifically for the L85 and just wonder...

I noticed the fps levels were jumping all over the place on the gun - 310, 315, 240, 280, 310, 240...

Anyway, opened the tophalf of the gb again to find the piston head cracked (see pics.)
It wasnt as obvious as it looks in the pics. Full of grease and in-line - it was hard to see at first. I just lifted the top of the piston head to show the crack for the pic.








Also, another silly question - I understand the L85 air nozzle is specific but is the G&G L85A2 hopup unit specific to the gun or will any G&G m4 generic type unit work ok.

Thanks in advance.

Masada

I'm not sure on the nozzle issue there aido, but the piston head is a normal one, its just the piston itself that's different.

defenderdude

Masada wrote: »

I'm not sure on the nozzle issue there aido, but the piston head is a normal one, its just the piston itself that's different.

Cool - as I thought:p (well hoped:o).

Thanks as always Richie.

defenderdude

I figured it's better to continue this thread rather than start another for the same gun...


Anyway, did a few modifications to this damned gun and it still sucks. Just doesnt want to work consistently in semi...

New piston, nozzle, piston head, blowback disabled, stronger spring, trigger contacts, new battery etc...

fires more consistently (sorta) but just jams in semi after maybe 5 or 10 shots (if lucky). Grrrrrrrr.

Looks like I am going to do the piston/spacer and sector gear modification but before I do I was going to try replacing the motor.

Not sure but I am assuming a high-torque as opposed to hi-speed motor would be what's required?

It's got to be one of the nicest finished guns on the market but my patience and pockets are running thin...:( :rolleyes:

DeBurca

If you had an issue with burned contacts in the past then you may have the same problem again
I think it may be worth while fitting a MOSFET as this will reduce the current running through the contacts to something in the order of 1% of the normal current and eliminate any possible problem with burned contacts
If you fit a MOSFET with active breaking it would prevent any possible overrun of the gearbox and always stop the motor thus preventing it doing a half cycle

If you have fitted a stronger spring then a high torque motor would be of more use to you to help maintain a better ROF
But try the MOSFET first, the worst it will do is improve trigger responce and it may sort out your misfire issue

deceit

All these g&g l85a2's cause problems like this once dropped to 1joule. I bought a new one had the same problem and replaced it with another and exactly the same thing. Two other people i've spoke too so far have had the same problem and havent fixed it yet.
On the first one I got all the wiring/contacts replaced even though they where perfect and it still didnt sort it.
http://www.redwolfairsoft.com/redwolf/airsoft/Accessories_AEG_Misc_Gearbox_Parts_RWC_L85A1_Piston_Spacer_Kit_Version_2.htm
(They had them in stock a few days ago)
This is supposed to fix it, I havent tried yet as doesnt bother me as can fire semi while auto is selected pretty easy and the looks and quality of the gun makes me look past the little niggly bit.

Oh and on another note, one thing in the A2 you dont have to disable the blowback it doesnt damage the gun like the a1 variant did as its piston has one less tooth and has a slightly altered gearbox so the top part that can come loose cant fall into the gearbox shredding it.

Decoy

Motor: 25000 rpm Hi-torque Long axis

http://www.guay2.com/web/our_product/l85a2.php?lang=en

Keegan

My dad had the same issue with his stubby killer (only thing JG about it was the gear box shell). Took out the motor and stuck in a brand new one, hasn't had the issue since. Not a techie but from what I was told the old motor was just burnt out.

J.D.R

Hey, just looking for a simplified version of the fix if possible.

I have an Army armaments L85 with the exact same problem stated in the OP, it will fire twice in semi, then won't, then twice... but everything else about the gun is great, accuracy, range, ROF, all brilliant, just that one problem.

TO fix the semi issue, will I have to redo the internals like you did, or would replacing the motor solve the issue?

Dread-Lock

You need the part deceit listed. http://www.redwolfairsoft.com/redwolf/airsoft/Accessories_AEG_Misc_Gearbox_Parts_RWC_L85A1_Piston_Spacer_Kit_Version_2.htm

DeBurca

Dread-Lock wrote: »

You need the part deceit listed. http://www.redwolfairsoft.com/redwolf/airsoft/Accessories_AEG_Misc_Gearbox_Parts_RWC_L85A1_Piston_Spacer_Kit_Version_2.htm

I don’t see how that will help the semi auto problem
It is in essence a means of using a standard 15 tooth V2/V3 piston instead of the 18 tooth piston that is normal for that type of gearbox
You are in fact short stroking the piston only pulling it back 15 teeth instead of 18 teeth

All in all a clever idea in allowing you to use more readily available part in a non standard type gearbox

deceit

DeBurca wrote: »

I don’t see how that will help the semi auto problem
It is in essence a means of using a standard 15 tooth V2/V3 piston instead of the 18 tooth piston that is normal for that type of gearbox
You are in fact short stroking the piston only pulling it back 15 teeth instead of 18 teeth

All in all a clever idea in allowing you to use more readily available part in a non standard type gearbox

You can do it this way but it removes the pre tensioning feature or i've seen on some other websites (will try find if you want) where they alter the original gear sector so fixs it and keeps the pre tensioning feature. I've tried on my gun now if i hold in the button for it i can switch between both and works, I wouldnt put something to hold the button in though as i'm not sure how it works and if it will damage it.

defenderdude

J.D.R wrote: »

Hey, just looking for a simplified version of the fix if possible.

I have an Army armaments L85 with the exact same problem stated in the OP, it will fire twice in semi, then won't, then twice... but everything else about the gun is great, accuracy, range, ROF, all brilliant, just that one problem.

TO fix the semi issue, will I have to redo the internals like you did, or would replacing the motor solve the issue?

Like dread said, you need to change the piston (use a regular V2 or 3 one witha spacer to make up the length of the one were're replacing) and one of the sector gears (as opposed to cutting teeth off the existing one).

Dont think the motor will solve the issue on it's own tbh (if at all).
I need to get a new motor for another gearbox I am working on and this is just another excuse to help me justify the expense...:rolleyes:

The piston and gear chage will / should solve the problem ok. Might slow the responce a bit, but no slower than regular gearboxes.

They're a bit of a head wrecker. :rolleyes:

defenderdude

DeBurca wrote: »

If you had an issue with burned contacts in the past then you may have the same problem again
I think it may be worth while fitting a MOSFET as this will reduce the current running through the contacts to something in the order of 1% of the normal current and eliminate any possible problem with burned contacts
If you fit a MOSFET with active breaking it would prevent any possible overrun of the gearbox and always stop the motor thus preventing it doing a half cycle

If you have fitted a stronger spring then a high torque motor would be of more use to you to help maintain a better ROF
But try the MOSFET first, the worst it will do is improve trigger responce and it may sort out your misfire issue

Thanks Kevin

I think the MOSFET is a great idea. The old contacts were burned to sh1te ok (as can be seen in the pics at the start of the thread). Changed them but it's really just a matter of time before they go the same way I guess.

Can you recommend a particular MOSFET you've used or source for one.
I understand part of the issue is caused by softer springs (needed to downgrade to Irish law levels) and the stronger spring when used with a vented cylinder can sort the issue and be ok power wise.

I might just do the piston/spacer/V2 sector gear mod anyway and see what happens. The gearboxes are nice and fairly easy to work on. The motor torque thing just occured to me and although it's a long shot - I dont know how many rounds or what use the old stock motor has had on it. (very little I am guessing as it was never opened before I got it.)

DeBurca

defenderdude wrote: »

Thanks Kevin

I think the MOSFET is a great idea. The old contacts were burned to sh1te ok (as can be seen in the pics at the start of the thread). Changed them but it's really just a matter of time before they go the same way I guess.

Can you recommend a particular MOSFET you've used or source for one.
I understand part of the issue is caused by softer springs (needed to downgrade to Irish law levels) and the stronger spring when used with a vented cylinder can sort the issue and be ok power wise.

I might just do the piston/spacer/V2 sector gear mod anyway and see what happens. The gearboxes are nice and fairly easy to work on. The motor torque thing just occured to me and although it's a long shot - I dont know how many rounds or what use the old stock motor has had on it. (very little I am guessing as it was never opened before I got it.)

I have fitted a few MOSFETs to a variety of AEGs but have never used one with active breaking
Although saying that I do have one here that I got a few weeks ago here one boards that I have plans for just need to get the time to fit it
The only place that I believe had them was Eirsoft a while back

Crash0744

None of the solutions mentioned will cure the semi stall as it is caused by the semi disconnect lever not lifting the switch high enough for it to pass over the trigger bar. Changing sector gear and fitting stock piston with a spacer might cure it for a while but the parts will wear and soon enough you getting stalls again. I cured the fault on my 2 r85's by filling the switch block and trigger to allow them to pass over each other easier. Be very careful if you try this as taking too much material from them can render your gat useless. Also if your going to fit a MOSFET to these model of aeg just remember to remove the extra wire in the trigger circuit or it won't work.

defenderdude

Crash0744 wrote: »

None of the solutions mentioned will cure the semi stall as it is caused by the semi disconnect lever not lifting the switch high enough for it to pass over the trigger bar. Changing sector gear and fitting stock piston with a spacer might cure it for a while but the parts will wear and soon enough you getting stalls again. I cured the fault on my 2 r85's by filling the switch block and trigger to allow them to pass over each other easier. Be very careful if you try this as taking too much material from them can render your gat useless. Also if your going to fit a MOSFET to these model of aeg just remember to remove the extra wire in the trigger circuit or it won't work.

Thanks for the info. Could you perhaps show a pic of the mod you did to the switch block and trigger - sounds like it's a good solution.

I replaced the sector gear and did the piston /spacer mod - it improved it a bit but I found myself just sticking in full auto and semi / fullauto firing like the with the AUG.

I tried a more powerful motor also - made no difference except increased my rof (which I didnt want) so put back in the stock G&G motor.

Thanks again Crash0744;).

Crash0744

Ive got a spare gearbox to mod. I should be doing it soon but I'll try to get some pics of the trigger mod in the next few days posted up

defenderdude

Crash0744 wrote: »

Ive got a spare gearbox to mod. I should be doing it soon but I'll try to get some pics of the trigger mod in the next few days posted up

Whenever you get a chance - no rush. Really appreciate it.:);)

swervy

HI Crash second on this as i have the same problem and would be very interested in a way to sort it out

bullets

I need to read this thread in full once I am sober.
When I bought my army branded l85' I had similar issues.
(that never got fixed)

It would fire, then half cock, and I'd end up pulling the trigger more than once to fire on semi. It would often spit out 2 bb,s at once, and fps would go up and down drastically. The gun was brand new at the time, so could not been burnt contacts. Don't know how a motor or gearbox could cause the issue if it was firing at 1j on semi only. Will read with intrest in the morning.

~B

Gpruitt54

J.D.R wrote: »

Hey, just looking for a simplified version of the fix if possible.

I have an Army armaments L85 with the exact same problem stated in the OP, it will fire twice in semi, then won't, then twice... but everything else about the gun is great, accuracy, range, ROF, all brilliant, just that one problem.

TO fix the semi issue, will I have to redo the internals like you did, or would replacing the motor solve the issue?

I am not so sure that replacing the motor will fix this issue. But maybe.

I bought an Army Armament L85A1 on Ebay a few weeks ago. My L85 has the same issue, mine only gets one round in semi-auto. Full auto work great. I purchased a brand new lower gearbox from Evike. I installed it and guess what? The new gearbox is doing the same thing as the old one. So, clearly the issue seems to be in the design.

I bought a 9.6 volt 1600mAh small butterfly battery and it really increased the rate of fire (I highly recommend this upgrade). It comes with a small female Tamiya connector. So, you will have to install a small male Tamiya connector or use an adapter.

I plan to take the gearbox apart, clean it, shim it, and hope this helps. I am disappointed because it appears to be an issue with the gearbox itself. I love the L85 and I've wanted to add one to my connection for some time. So, I really want to fix this issue. Sure, I could keep it in full auto. I am doing that now.

Now that I have a gearbox that I can play with outside of the gun body, It seems like the sliding plate that covers the contact is not pulling back to its initial position. Both the old and new gearboxs are doing this. I've contacted Evike to see if their techs may have a solution.

If anyone knows exactly what needs to be replaced to resolve this, we would all appreciate it?

defenderdude

Gpruitt54 wrote: »

I am not so sure that replacing the motor will fix this issue. But maybe.

I bought an Army Armament L85A1 on Ebay a few weeks ago. My L85 has the same issue, mine only gets one round in semi-auto. Full auto work great. I purchased a brand new lower gearbox from Evike. I installed it and guess what? The new gearbox is doing the same thing as the old one. So, clearly the issue seems to be in the design.

I bought a 9.6 volt 1600mAh small butterfly battery and it really increased the rate of fire (I highly recommend this upgrade). It comes with a small female Tamiya connector. So, you will have to install a small male Tamiya connector or use an adapter.

I plan to take the gearbox apart, clean it, shim it, and hope this helps. I am disappointed because it appears to be an issue with the gearbox itself. I love the L85 and I've wanted to add one to my connection for some time. So, I really want to fix this issue. Sure, I could keep it in full auto. I am doing that now.

Now that I have a gearbox that I can play with outside of the gun body, It seems like the sliding plate that covers the contact is not pulling back to its initial position. Both the old and new gearboxs are doing this. I've contacted Evike to see if their techs may have a solution.

If anyone knows exactly what needs to be replaced to resolve this, we would all appreciate it?

Tried replacing the stock with a G&P motor and it just increased the ROF. No improvment in semi.
I did the sector gear and piston mod and while it improved - it's still not 100%.
It appears the best option is to keep the original spring (overpowered) and reduce the power to sub 1 joule by changing the cylinder to a vented one (which will reduce the power output but keep the gearbox cycling to set itself for the next shot.

It's the type of gearbox used - it precocks the piston prior to every shot (like the TM PSG-1). In theory it's a great idea and should increase response time, in reality - it doesnt work properly.

The Version 1 (L85A1) had this and other problems - eating itself, blowback failing etc and while the blowback was fixed and the chewing pistons issue was sorted by G&G using a piston with the first couple of teeth removed for reliability - they didnt sort the semi jamming issue (on downgraded guns).

The ARMY L85 is an exact clone (copy) of the G&G L85A1 model - it has the same issues (but without the build and finish quality of the G&G).

Shimming wont sort it either but will make it run smoother and quieter perhaps.

The vented cylinder is the best option - and the easiest to do. (I havent tried it yet so I cant vouch for the effectivness)
The sector gear and piston mod has improved mine a bit and allows me to use standard V2/3 sector gears and pistons.

Note: Be careful as the piston and cylinder are not standard - they are longer!

Gpruitt54

defenderdude wrote: »

Tried replacing the stock with a G&P motor and it just increased the ROF. No improvment in semi.
I did the sector gear and piston mod and while it improved - it's still not 100%.
It appears the best option is to keep the original spring (overpowered) and reduce the power to sub 1 joule by changing the cylinder to a vented one (which will reduce the power output but keep the gearbox cycling to set itself for the next shot.

It's the type of gearbox used - it precocks the piston prior to every shot (like the TM PSG-1). In theory it's a great idea and should increase response time, in reality - it doesnt work properly.

The Version 1 (L85A1) had this and other problems - eating itself, blowback failing etc and while the blowback was fixed and the chewing pistons issue was sorted by G&G using a piston with the first couple of teeth removed for reliability - they didnt sort the semi jamming issue (on downgraded guns).

The ARMY L85 is an exact clone (copy) of the G&G L85A1 model - it has the same issues (but without the build and finish quality of the G&G).

Shimming wont sort it either but will make it run smoother and quieter perhaps.

The vented cylinder is the best option - and the easiest to do. (I havent tried it yet so I cant vouch for the effectivness)
The sector gear and piston mod has improved mine a bit and allows me to use standard V2/3 sector gears and pistons.

Note: Be careful as the piston and cylinder are not standard - they are longer!

So, would you say this is an issue that cannot be resolved, and that the design of the G&G/Army L85 is flawed?

defenderdude

Gpruitt54 wrote: »

So, would you say this is an issue that cannot be resolved, and that the design of the G&G/Army L85 is flawed?

Maybe a flawed design but I'd have thought it can be resolved ok.

I'd like to see pics of Crash0744's fix mentioned in previous posts. It sounds like it too, could be a fix.

Gpruitt54

Crash0744 wrote: »

Ive got a spare gearbox to mod. I should be doing it soon but I'll try to get some pics of the trigger mod in the next few days posted up

Hay Crash0744
Looks like you have several L85 owners waiting to see what you come up with.