loud motor/gearbox

[kasaran]

So tinkering and fielding my SVU, one of my main gripes is how loud and buzzy the motor sounds when firing.  this may be exaserbated by the fact its a bulpup and its positioned right by my ear.   does anyone know of a replacement motor that is considered quiet?  or maybe a reshim job might help it run smoother?

[AK47frizzle]

It's definitely a shim job that is needed, not a replacement motor. As well as probably working out the correct motor height. The pinion gear on the motor is most likely not contacting with the bevel gear (first gear it contacts in the gearbox) very well, which leads to the gear crunching noise.

 

 

[ImTriggerHappy]

The only way to say what the issue is if there is one is to hear it. Without that any advice is just conjecture or someone talking out their arse.

[Asomodai]

Yes, bullpups tend to be louder when playing as your ear is right next to the gearbox. My ICS L85 is particularly loud. 

 

If it seems louder when your ear is not pressed up against it. It's more likely to be shim or motor height then the motors. The motor itself doesn't make much noise. Its the meshing the with gears. 

 

 

[kasaran]

Righto.  Well may look into shimming.  It just sounds much less happy than my other aegs, including my l85.  And as its a weird gearbox, spares will be next to imossible to source.  if it busts it would likely make the gun a write off.

 

The last people to pop it open was zeroone.  But i didnt ask for a shim job.  Im not so confident now to do it myself. Guess ill find a tech.  

[Iceni]

If it is motor engagement then this might apply.

Shim job would cut down on some of the noise. With it been a bullpup it's always going to be noisy.

Having just done my first 13:1 gear conversion that might be something you could do.

12/13:1 gears run with a slower (but more powerful) motor, So the motor and gears spin less for each shot.  

The build I just completed was 13:1 gears matched to the ASG ultimate CNC 30,000 motor.

With an M120 it was chucking out 1.6J at 21rps on 7.4v lipos.
With an M110 that has been cut by 1.5 coils it's doing 1.12J at 24rps on 7.4v lipos.

Pair that up with a plastic silent piston head, and the correct cylinder head and you could make some significant noise reductions. 

You will always hear the gears in a bullpup the design of them means you are resting your chin and ear directly over the gearbox and all noise is going to get directly transferred to your head.

Another option might be having a word with a local dressmaker, And having them make up a stock sock in neoprene with a zip at the bottom. There is no way to pack it internally because of the design of the gun so this might be a good solution to make it a bit more comfortable on the ears.

You should be able to have a tech do any of the above work bar the sock.

Going over to a 13:1 set isn't cheap. Doing it yourself you have a basic outlay of the gears, motor, bushings, and heads. That's going to cost £100 ish just in parts.

Sticking to 18:1 and adding a motor is pretty easy. If the shimming isn't right then chances are it'll still be wrong even after a motor swap.


One thing you might try is the motor height adjustment screw.

It'll be on the bottom of the motor. So remove the back cover to the gearbox. Then there should be a motor in a cage, and at the very bottom there will be a screw that looks directly up into the motor. Get the correct drive for the screw it might be allen or a flat screwdriver ect. And just give it half a turn and see if it make it sound better or worse. If it sounds worse try half a turn in the other direction.