m4 with new bushings and gears... it doesn't fire!

[tommyVega]

Help!

I have just changed gears on my CA m15a4 sportline (the sector gear had stripped), and also put on new metal bushings to replace the plastic stock ones (very tight fit btw, I had to hammer then in).

I also re-shimmed the gearbox (first time I do it): the gears didn't move sideways, but they where fairly free to rotate (a little bit of resistance).

The problem is that the gun doesn't fire. The gears turn half a cycle and tension the spring nearly to the max, but it looks like the motor doesn't have enough strength to push the piston back for the last 5-10 millimetres, so it won't release and shoot.

The battery is charged (it works with another aeg), and if I try the motor on the gearbox without piston/spring it spins nicely (very little rattling sound from the gears), also the motor height is adjusted properly...

any idea??

[North West Outpost]

Re: m4 with new bushings and gears... it doesn't fire!

Re shim it so there is vertually no resitance. With bushings there needs to be a tiny ammount of movement or they are too tight.

They should also be a tight fit into the gear box, a lot of people epoxy them into the gear box if they are loose as it defeats the object of solid bushings to have them loose on the gear shaft and loose in the gear box. It just induces stress.

[tommyVega]

Re: m4 with new bushings and gears... it doesn't fire!

I thought that might have been the problem... I'll try again tomorrow with a fresh mind...
Also, anything particular I have to look at when I install the motor? Beside height of course...

[North West Outpost]

Re: m4 with new bushings and gears... it doesn't fire!

If it worked befor you took it out, it really should be fine after too. I would look at the shimming first. As it is much easyier to adjust the motor height after shimming if it is needed.

[seansamurai1]

Re: m4 with new bushings and gears... it doesn't fire!

The obvious it spins the right way really, make sure the terminals are the right way round.
Admittedly that would cause a full jam when it hits the anti reversal latch the wrong way.

[tommyVega]

Re: m4 with new bushings and gears... it doesn't fire!

Thanks!
I'll try tomorrow and post the result...

[tommyVega]

Re: m4 with new bushings and gears... it doesn't fire!

Just a quick update on this one...
After trying to re-shim the gearbox in any possible way, and checking everything (with no luck), I managed to get hold of some spare CA Sportline gears (the m4 is a CA SL), to replace the new "standard" CA gears I bought.
And surprise surprise, it worked at the first attempt!

The question now is, why would a brand new set of CA gears not work on a CA M4?