VFC Scar-L Gearbox Lockup

[AnthonyG]

Just got one of these off the classifieds. Worked fine when I tested it, now the gearbox is locked up (motor attempts to spin, but no winding in the gearbox). I can turn the motor on its own, but not when it's all connected up. I thought it might be the engagement height of the motor, but backing it off didn't seem to have an effect.

I'm wondering if this could be due to the VFCs auto-shimming feature causing the gears to bind. Im thinking about opening the gearbox to check the internals, but I thought I'd get some opinions here first on what to try.

I'm still kind of new to airsoft and tech-ing my gear, but have had enough practice on my M4 to be comfortable with a V2 gearbox.

[EOD Steve]

Possibly something busted inside the mechbox, jamming the gears. (piston, tappet plate, who knows)
Factory VFC shimming is always good enough and would not cause the symptoms you described. Unless the mechbox was opened up and poorly shimmed.

Good luck with the selector switches. If you lose one of the ball-bearings, I have spares.

[lurkingknight]

if you're going to take it apart yourself you need a tiny as fuck hex key to get the selector off the gearbox.

[AnthonyG]

At one point I disengaged the motor, reingaged it, was able to fire a few rounds, went to fire again and it was jammed up. I'm pretty sure the previous owner never opened the gearbox because it still has the warranty sticker.

I can see the spring when it jams, so that means the piston is not engaged, right?

My other thought was that maybe my battery is having a hard time pulling the spring? I'm using a 2-cell lipo.

[EOD Steve]

7.4v lipos should cycle any stock VFC mechbox with zero issues, unless it's something like a 400mah one LOL

What do you mean "I can see the spring when it jams"?

Is your battery charged.....?

[lurkingknight]

I have seen the vfc spring guides unthread themselves and start to come apart inside the gearbox.. when the nose piece unthreads it will open a gap between it and the bearing and the spring can jam into the gap causing the piston to hard jam into the spring.

This might not be your issue if you say you're pulling the motor down and pushing it back up, since you would need to access the arl to release the spring to get it to cycle again, but it might be another thing to check when it's opened up.

Is the piston clear or blueish clear? That would be the stock piston... if it's not clear, then it's not stock and it could be a badly fitting piston jamming in the gearbox rails.

[RainyEyes]

Troubleshooting tips and steps:
Check the fuse
Check battery.
Check the motor
Check the internals

Check the fuse: make sure it isn't burned out. This means there's an internal problem somewhere. Fuse ok? Move to next step.

Check battery: is it charged to full capacity? How are you charging?

Check motor: take the motor out and pull the trigger with it outside the gearbox. Is it spinning? Sparks flying like Taylor Swift? If yes, replace motor.

Internals (last resort if none of the above fixes your problem): open if you're experienced. If not, take it to a gun tech. You save time and money taking it to a pro, worry free, that they'll figure it out for you.
If you want to tinker: look at obvious signs of breakage. Front post where the cylinder sits is the usual area of failure. Afterward, look at the gears, piston, etc.

[BobbyDangerous]

Too me it sounds like the piston is stuck. Might be out of the guides in the gearbox

[lurkingknight]

brushed motors throw sparks at the brushes from time to time.. that's normal.

I haven't seen fuses on vfc guns in a while.

[AnthonyG]

This is a 2010 model. It has a big ass fuse.
Original clear-plastic piston.

[BobbyDangerous]

I also thought of this and it's happened to me before. There was a screw caught in the motor. I had to take the motor apart and remove the screw. Was actually pretty easy. If you can unscrew the top of the motor and take that apart that might help.

[AnthonyG]

Originally Posted by lurkingknight

if you're going to take it apart yourself you need a tiny as fuck hex key to get the selector off the gearbox.

Tiny as fuck x2

BBs for reference

[lurkingknight]

Think it might actually be smaller lol

[AnthonyG]

Dont want to turn this into too much of a play-by play.

I released the anti-reversal latch before opening and it sounded like the gears uncoiled.

This is waht the box looks like upon opening.
The grease looks pretty chunky:

[BobbyDangerous]

Looks fine to me. Check the motor