ICS L85 TDC hop mod and mosfet?

[NickM]

Been reading loads on some of the sniper forums about the top down centre mod on hops, basically a screw is fitted that pushes directly on the hop arm over the nub. It is fitted through the metal and I'm thinking that there is a slight twist on my hop arm due to the way it is shaped that it might be a good way to improve accuracy.

 

Anyone know if it might work on an AEG, I might do this in combination with shimming the hop? I don’t want to wreck the gun.

 

The trigger response is not great, I was having a look at maybe installing a mosfet but can’t seem to find out if anyone has ever done it on one of these. Has anyone seen a guide for this or know someone who has done it so I can see some pictures/find out how they did it. I’m not really wanting to spend £85 on a new motor (especially as mine seems to be working really well at the moment) which seems to have been Ed’s solution.

 

If any of the above sounds like a really bad idea or you’ve heard of someone doing it before on an AEG or even better on an L85 please let me know.

 

Cheers, Nick

[Airsoft-Ed]

You can get other hi-torque motors for a lot less than I did, I didn't take much time to look into it so I just went with the most expensive because I'm an idiot lol.

You could also try shimming the gears, or buying hi-speed gears. Or, you could buy a weaker spring and get a tighter barrel, weaker spring means the motor doesn't have to work as hard to turn the spring over so it can do it faster, and a tightbore will give you back the fps you lose from having a weaker spring.

Or of course, you could just get a higher voltage battery. If the gears are shimmed right then the ICS L85 gearbox ought to be able to take an 11.1v LiPo relatively easily, I've heard of them going up to 45 rounds per second before the piston shredded.

 

I don't find that the hop is really bad enough to try any special fancy mods, I just use a madbull blue rubber and a Big Out H Nub, which can be bought from Fire-Support. I'm planning on trying out other hop rubbers though.

[NickM]

Cheers Ed, I'm thinking about trying to make sure all the air seals are spot on in the L85 and then downgrading the spring, might help. I might start using my 9.6V battery instead of the 8.4V I run normally, (I’m not happy about LiPo just at the min) and stick with semi. I've got a 6.03 tightbore on order (I was using a twist barrel) and will be making an aluminium hop arm so I’ll see how that goes. I see you’ve picked one up.

 

I was thinking about shimming the gears in an effort to quieten the gearbox, any chance you could point me in the direction of the correct size shims. I’ve never done it and most of the vids I can find don’t explain how to figure out the best setup. Also you wouldn’t happen to know how to work out the angle of engagement thing people are on about? Or maybe explain what mine should look like

 

By the way, I've found out why my gun keeps locking up on semi. If you press on the fire selector leaver and it pushes in a bit chances are it will miss the bump that stops it going past semi. If the selector leaver goes past it moves the black leaver on the outside of the gearbox and pushes the rearmost grey bar on the trigger box down to stop the trigger sliding forwards. There is a screw on the other side from the selector and mine was a touch loose. Amazing difference it's made! It’s also stopped it switching over so much from the 3 point sling rubbing on it.

[Airsoft-Ed]

Cheers Ed, I'm thinking about trying to make sure all the air seals are spot on in the L85 and then downgrading the spring, might help. I might start using my 9.6V battery instead of the 8.4V I run normally, (I’m not happy about LiPo just at the min) and stick with semi. I've got a 6.03 tightbore on order (I was using a twist barrel) and will be making an aluminium hop arm so I’ll see how that goes. I see you’ve picked one up.

 

I was thinking about shimming the gears in an effort to quieten the gearbox, any chance you could point me in the direction of the correct size shims. I’ve never done it and most of the vids I can find don’t explain how to figure out the best setup. Also you wouldn’t happen to know how to work out the angle of engagement thing people are on about? Or maybe explain what mine should look like

 

By the way, I've found out why my gun keeps locking up on semi. If you press on the fire selector leaver and it pushes in a bit chances are it will miss the bump that stops it going past semi. If the selector leaver goes past it moves the black leaver on the outside of the gearbox and pushes the rearmost grey bar on the trigger box down to stop the trigger sliding forwards. There is a screw on the other side from the selector and mine was a touch loose. Amazing difference it's made! It’s also stopped it switching over so much from the 3 point sling rubbing on it.

 

Sorry, slightly delayed reply.

 

I just bought a standard shim set from Patrol Base for about £4, I think the ones I have are .1 .2 and .3mm in diameter. But I'd say to just buy one or two packs of the smallest set you can find, I worked out the ideal spacing by using the .1mm shims and then swapped them out to .2 or .3mm ones accordingly.

If I needed 3 of the .1mm ones then I'd just swap them for a .3mm one, for example.

 

Shimming is pretty straight forward, just take all the stuff out of the gearbox and just have the gears sat in there, you want at least one shim on both sides of every gear just to ease the spin of it, but all the others ought to go on the opposite side to the serrated gear side, or the back of the gear - this is so that the shims will force the gears to mesh together better, so there's less chance of them slipping or meshing to a different degree each time you cycle the gearbox by pulling the trigger.

The gear that the motor meets with will probably have a shim or two on it already, you can just leave that one as it stands because the motor will push against it enough for shimming it further to be unnecessary.

 

To shim the remaining two gears just add the thinnest shims you have to the back side of the gears, then close the gearbox shell - don't bother screwing it together or adding the piston and everything back in, just the gears and the shims.

 

Then poke at the shafts that the gears are mounted on from outside the gearbox, if there's movement in them, add more shims. Just keep doing that until there's no movement, then reassemble the gun and test. If it sounds strained, then you've added too many and they're jamming the g'box, open it back up and remove a shim from each gear.

 

It's just a case of rinse and repeat until the gearbox sounds normal again. It's pretty unlikely you'll actually notice a huge difference, or really any at all. I just managed to pick up a tiny weenie increase in trigger response, but the sound it makes is about the same.

 

But, every little helps, right? Plus, it's an easy enough task to just do it anyway.

 

The angle of engagement refers to how your piston's first tooth meets the first tooth of the pinion gear. Just open the gearbox up, push the air nozzle inwards and take the second gear out (to allow free movement of the pinion gear) and then just spin the pinion gear with your fingers until it meets with the piston.

If it meshes with the first tooth of the piston perfectly then you don't need to do anything. If it tries to bite the second tooth on the piston then you need to add a spacer between the piston head and piston to correct the gap, or add a cushioning pad to the back of the cylinder head so that the piston will come to rest further back. It's unlikely you'll need to sort this out, every gun I've ever had has the correct AoE from the box, I've never actually seen a gun where it's wrong, so I wouldn't worry about it too much. It's only really something you have to check if you're swapping out the piston, piston head or cylinder head, as they could all potentially adjust the length of travel by altering the amount of space in the cylinder.

If you're sticking with the stock cylinder head, piston and piston head then I wouldn't worry about it.

 

Good to hear you've figured out how the trigger mech works well enough to sort issues with it out for yourself, I always find it quite satisfying when I'm able to figure out mechanical stuff like that lol.