How important is it to shim/grease gear box?

[blackjack21]

Hi all. more newb questions.

I have a gun which now shoots very very well. But it is loud and my buddies tell me it is the gear box.

I have one set of people telling me the best thing it to take the gun apart and reshim and grease my gear box.

I have another set telling me that now that I have the gun shooting well not to F with it till it breaks.


What do you guys think?

[ThunderCactus]

shimming is pretty critical, if you don't want it to break within a season and cost you $60-$140 in parts, you better get back in there and shim it right.
Just be sure it really IS the mechbox and not just the motor height

[Renegade)]

Shimming and Lube is very important. Most stock guns come OK shimmed, so if you have noise, check motor height. Adjust the little screw at the center of the grip plate until it sounds normal again. If this doesnt help, you may need to relube or adjust the shimming of the mechbox.

[KenTsui]

Originally Posted by blackjack21

Hi all. more newb questions.

I have a gun which now shoots very very well. But it is loud and my buddies tell me it is the gear box.

I have one set of people telling me the best thing it to take the gun apart and reshim and grease my gear box.

I have another set telling me that now that I have the gun shooting well not to F with it till it breaks.


What do you guys think?

Is the gun stock and what is it?

[lurkingknight]

a properly shimmed gearbox is pretty quiet when the motor height is adjusted correctly.

An amazingly shimmed gearbox's only noise will be just the motor noise.

badly shimmed gears can cause pinion wear on the motor, even with proper motor height adjustment... because you could have the correct motor height, but not proper engagement between bevel and pinion. This is why a lot of builders advocate shimming to the pinion first with the half box/motor mounted method., while others just start throwing shims on. You could have a great shim job but the engagement of the bevel to pinion could be too tight because the bevel is too high, or the pinion is engaged too deep because the bevel is too low. Depending on the make of the bevel and pinion as well the shimming will vary because the shape of the teeth on both.

Premature gear wear, bearing failure, gear failure, high motor amp draw, gearbox noise, piston locking... they can all be symptoms or results of a poor shim job.

Grease on the gears is not as important, they generally don't contact one another except on the teeth. Greasing the piston O-ring, the tappet slide channels, nozzle o-ring and piston slide channels is super important. In high rates of fire the compression and friction being generated can actually heat up the cylinder wall. Heat and rubber aren't necessarily good when you consider that hot and cold cycles are what harden rubber. Keeping the O-rings lubed can keep your compression elements sealing properly over the course of their lifespan.

tldr: shimming is super important. greasing airseal components is super important. greasing gears won't hurt.

[vondnik]

all depends on how long you want you gun to function properly...

ungreased and mis shimmed gearbox have a lifespan mesured in minutes while perfectly tune boxes can last decades... yes decades... (my rpk gearbox was changed after 13 years of extreme use.... and not because it was dead just becase I had pitty on it...)