VFC Scar-l - Gears and motor upgrades

[THE FNG]

Hi all;

 

The time has come for a gearbox upgrade for my VFC Scar-l.

I had to replace a gear inthe scar as I lost the self-shimming piece when I dropped it in the garage...can't find the little shite anywhere.

It sounds a bit off and its ready for a full revamp inside.

 

I've never done a whole new gear/motor set before. As it stands, it is all vfc stock (self shimming).

 

My question is:

I am looking at higher torque rather than r.o.f as I'd rather have the snappy trigger response. What would be the best motor (has to be long shafte type) and gear set?

What ratio, brand etc?

 

Apologies for being so vague....I sort of get how it all works but I wanted to make sure as it's my pride and joy!!

 

 

Thanks all,

 

Andy

 

[cyrexx]

Motor wise I have always gone for the Lonex A2, It will pull an M170 spring with ease, if you want something a cheaper there is the SHS High Torque or the ZCI High Torque both are good but are slower than the A2 I've found.

 

Gear wise I would recommend SHS gears, cheap (£15 on fleebay) and reliable, the lower the ratio the better e.g. 13:1 for the gear ratio.

 

Are you using LiPo batteries?

[straffham]

As ^^

 

try ak2m4 on this forum for SHS/ZCI motors & gearsets etc, Pete is a great guy and will prob offer a forum member discount if you message him. Highly recommended.

 

www.ak2m4.co.uk/internal-parts/gears

[Lozart]

Motor wise I have always gone for the Lonex A2, It will pull an M170 spring with ease, if you want something a cheaper there is the SHS High Torque or the ZCI High Torque both are good but are slower than the A2 I've found.

 

Gear wise I would recommend SHS gears, cheap (£15 on fleebay) and reliable, the lower the ratio the better e.g. 13:1 for the gear ratio.

 

Are you using LiPo batteries?

 

 

All of that is fine for high speed - the OP is looking for high torque.

[THE FNG]

I don't use lipo's....im old school and still run nimhs'.

Just to clarify; I'm looking at trigger response however, here's my current setup:

 

-Vapex 9.6v nimh

-M90 spring (its an shs one so its probably closer to m100; puts out 335fps (0.2's) with a tightbore)

-All stock internals (minus spring and barrel)

-Stock Motor

 

Would you guys think I'd need speed or torque. The only reason that I wanted torque was the trigger response. The R.O.F Doesn't really matter to me as I am cqb-only atm. I'm assuming I'd need high torque for this?

Does high torque affect the time it takes to pull the trigger between shots in semi? I have been using semi and pulling the trigger too fast for the gearbox to handle a few times.

[jcheeseright]

If you want trigger response the single biggest gain you can get is using LiPo batteries. Doesn't matter how beefy your motor is, if your battery cannot discharge enough current to run it up quickly you won't get significant benefits.

[straffham]

As said above a more powerful battery will give you faster trigger response and rof with a given motor, so this would probably be the best way to go but fitting a mosfet would be a good idea to protect the trigger contacts from burn out. If you don't want to go LiPo maybe consider a 10.8v NiMh from Component Shop if you have space to fit one, though again a mosfet would be a good idea.

In general in a given set up a high TORQUE motor will spin up faster than a normal AEG motor, with more torque (designed for pulling stronger springs) when the trigger is pulled, but they don't have as high RPM as a normal motor, so you will get fast trigger response but ROF would probably be lower than with a standard motor. A high SPEED motor will have a higher RPM than a standard motor, thus higher rof, but may only slightly improve trigger response over a standard motor as it doesn't spin up from zero to full speed as instantly as a hi torque motor.

So its a matter of what you want out of the gun really.

[cyrexx]

 

 

All of that is fine for high speed - the OP is looking for high torque.

 

 

He's actually looking for "snappy trigger response", what I recommended would result in a very "snappy trigger response"

 

 

 

+1 for www.ak2m4.co.uk delt with him before (bought some Core motors from him) great service

[Lozart]

I'd say he's better off with LiPo batteries and a decent MOSFET personally.

[BrightCandle]

Is the issue with trigger response the length of the trigger pull or is it that the motor isn't finishing its spin when you let off the trigger? I just want to make sure that you are solving the right issue as a lot of trigger response is in the dead space on a lot of guns.

[dex]

As above. Lonex a2,decent gears (lonex, shs), mosfet, lipo. Job done.

[THE FNG]

Is the issue with trigger response the length of the trigger pull or is it that the motor isn't finishing its spin when you let off the trigger? I just want to make sure that you are solving the right issue as a lot of trigger response is in the dead space on a lot of guns.

 

I have had instances where the motor isn't finishing its spin when letting off the trigger. This was my main concern.

I wanted to do an overall revamp anyway as vfc gears aren't known for thier reliability and so I wanted to upgrade the one thing that I have always relied on; a quick, semi-auto trigger finger. Never had an issue with this on previous guns but the scar hasn't performed quite as well in this area.

[Lozart]

 

I have had instances where the motor isn't finishing its spin when letting off the trigger. This was my main concern.

 

 

Get a decent mosfet then. A lot less hassle than dicking about with gears.

[THE FNG]

Hi all, thanks for all of the great advice.

I ended up getting the lonex high torque motor as the vfc stock one is pretty shite. Installed and notiecd an immediate improvement to every aspect of the motor.

Also got the 13:1 gear set but not added them in yet; went for these as the stock gears are also shite and needed replacing. Next step is to get a mosfet and lipo; never done a mosfet so I'l going to be learning up on them over the next week or so...nice little project on my xmas week off!!

[cyrexx]

My advise for you would be:

 

1) Fit the 13:1 gear,

2) Look at what mosfet you are going to get and where you can fit in the gun (but don't buy it just yet).

3) Buy the biggest LiPo you can fit in the gun. (hobbyking is a great place to get LiPo batteries if not the best)

3) Try out the LiPo in the gun to see how much over spin you get and if it doubles shoots from the over spin on semi auto, this will let you know if you can get a normal mosfet or an active braking mosfet.

 

Doing this will save you some hassle and money.

[THE FNG]

Rather than starting a new topic, I'm bumping this one.

 

I'm going to turn this thread into my SCAR project. I've stumbled on another issue now and the whole revamp of the scar is just annoying me.

I tried to add a new piston to the scar when the stock piston stripped due to premature engagement but when I pulled the trigger it only cycled partly. When opening the gearbox, I found that the piston had been pulled back but not released....the spring was still compressed back and the piston was stuck on the last tooth of the gear (13:1 gear set).

I have since tried a 16:1 gear set in the gearbox but of course, as I tried to test it, the wires to the motor snapped and now I have to sort that out...fuming!

 

In theory, should the gearbox be able to cycle with the 16:1 set in? I probably should mention that I have also taken the bearing off the spring guide to help allow the cycle.

[jcheeseright]

Put the bearing ON the spring guide to help it cycle! That's what it's there for!

 

If 13:1 was getting stuck, 16:1 stands a better chance but there's no guarantee.

[THE FNG]

Right, I've tried the 16:1 and I'm having the same issue...

The piston is staying at the rear of the gearbox. It is being held there by the last few teeth of the gear.

Never had this issue before. I've also tried it with the original gears but the same is happening! Only thing different is the piston. The cylinder head is the stock head.

 

What is the best way to remedy this?

 

I've read a few threads online that say its poor motors...surely its not this as its got a brand new lonex a2 in there!

[jcheeseright]

sounds like your new piston is 'deeper' than the old one, compare them side by side with the spring in them and see if the spring sticks out further from the new one.

[THE FNG]

Tried that but they are both the same....getting really confused here as to what the problem is?!

[THE FNG]

Right; done some work since the last post.

 

Having recharged the battery completely and tried one or two other batteries, I have concluded that the issue was the battery connectors in the stock.

However, having had it firing again, I have encountered another(!) problem.

 

The issue now is that the tappet plate is bending upwards when the gun is fired. This is stopping the air nozzle from shooting back forward. I have tried it with a delayer chip installed and without. Both give the same results.

 

 

Does anyone know a remedy to this?

 

[dex]

Does the tappet plate move freely on its rails with the gearbox closed up?

 

Remove the piston and main spring and then screw the box up. Make sure you can push the air nozzle fully back without obstruction - try this with and without the tappet plate spring - without the spring in you should be able to push/pull the air nozzle in and out fully without it snagging or being obstructed - with the spring you should be able to push it back with a bit of force (smoothly) and it should snap back when you release it.

 

If the motion of the tappet plate is not smooth, check its seated in its rails properly and the the spring is installed the right way.

 

I cant see the front of the gearbox in your photo, so its hard to tell if there is some obstruction near the nozzle end.

[straffham]

assuming the spring you're using worked fine before it sounds as J.Cheeseright says like the piston is very slightly different somehow. I've known aftermarket pistons to vary and had the same problem you have.

Check the slide rails on side of the piston are exactly the same width as the original piston (as well as the groove between the rails being the same depth and width). Also did you check the piston moves freely and smoothely when you installed it? Simplest way to do this is to reassemble the GB with just the piston/piston head and cylinder in, no spring, screw it shut (don't just hold the 2 GB halves together) and then using a screwdriver insert it where the air nozzle would be and push the piston back and forth. It should move easily and smoothly. Any tightspots indicate something needs sanding down slightly (Spring torque in the equation can make a slight tight spot into a potential jam). Once happy make sure you use good lube on the whole length of the cast rails inside the GB, as well as on the spring guide.

Just another thought, are the battery, wiring and trigger contact switch in perfect condition? Any power loss here can lead to jamming like you describe too. Have you a more powerful battery you can try?

 

EDIT D'OH my messenger is slow, sounds like you've sorted the jamming now lol!

[THE FNG]

Does the tappet plate move freely on its rails with the gearbox closed up?

 

Remove the piston and main spring and then screw the box up. Make sure you can push the air nozzle fully back without obstruction - try this with and without the tappet plate spring - without the spring in you should be able to push/pull the air nozzle in and out fully without it snagging or being obstructed - with the spring you should be able to push it back with a bit of force (smoothly) and it should snap back when you release it.

 

If the motion of the tappet plate is not smooth, check its seated in its rails properly and the the spring is installed the right way.

 

I cant see the front of the gearbox in your photo, so its hard to tell if there is some obstruction near the nozzle end.

 

 

Thanks for the replies guys.

 

I've tried moving the tappet plate in the gearbox it moves fine with both the spring installed and absent.

I have put back together and cleaned it and tried it again. It is still having issues.

 

What I have noticed is that the air nozzle is staying back after pulling the trigger the first time. It is stuck back; there is no play and you cant push it backwards with a finger, nor can you pull it forward.

I have shone a torch in the geabox without disturbing it and can see that the tappet plate is in fact not beinding; it is in its rails and in line perfectly.

This leads me to believe that the tappet plate is being blocked so that it won't return?

 

 

When I fire it, the nozzle stays back. Then, when the trigger is pulled again, the nozzle shoots forward and then returns back.

[dex]

How does full auto go? It might be a cut off lever issue if its not cycling properly on semi.