Airsoft Canada - View Single Post - Shimming new gears issue

ao_tenshi · July 14th, 2015, 12:22

Hey ASC!

I have been trying to install a new set of gears (SHS 13:1) into my G&P M4, and have been having issues at the shimming stage.

Following numerous guides and tutorials on shimming religiously, I FEEL that I have done near perfect shim jobs. Even tested the gear movements with the gearbox screwed back together. However, the PROBLEM comes when i put the gun back together to test fire. Here are the symptoms I encounter:

1) Semi-auto firing - gun will seize during semi-fire (ok in full-auto)
2) Loud gear mechanical sound, I dont think its grinding as I've checked the gears after

My conclusion is that the gears are shimmed too tightly creating excess stress and friction.

The issue Im facing now is if i loosen the shim to a point where the gun doesnt seize in semi, then the play/movement of each gear axle is extremely large. Is this a normal thing or is my gearbox not built to spec? The other thing i notice is my selector plate is pushing the bearings as well...

Maybe folks with lots of shimming experience can shed some light on this.

Thanks in advance!

July 14th, 2015, 12:22	#1
ao_tenshi Trader rating Join Date: Apr 2011 Location: Toronto, Ontario	Shimming new gears issue - Is this normal? Hey ASC! I have been trying to install a new set of gears (SHS 13:1) into my G&P M4, and have been having issues at the shimming stage. Following numerous guides and tutorials on shimming religiously, I FEEL that I have done near perfect shim jobs. Even tested the gear movements with the gearbox screwed back together. However, the PROBLEM comes when i put the gun back together to test fire. Here are the symptoms I encounter: 1) Semi-auto firing - gun will seize during semi-fire (ok in full-auto) 2) Loud gear mechanical sound, I dont think its grinding as I've checked the gears after My conclusion is that the gears are shimmed too tightly creating excess stress and friction. The issue Im facing now is if i loosen the shim to a point where the gun doesnt seize in semi, then the play/movement of each gear axle is extremely large. Is this a normal thing or is my gearbox not built to spec? The other thing i notice is my selector plate is pushing the bearings as well... Maybe folks with lots of shimming experience can shed some light on this. Thanks in advance!