Reshimming?

[guiltyspark]

Sorry for the questions, but i have been surfing the sight and the web and cant seem to find out what reshimming is? Anyways, sorry if this information can be found on this website or on the web but i cant seem to find it. I would like to know what reshimming is because I hear JG guns need it and I want to know if its possible to perform by myself on my jg m4. thank you in advance!

[diamond_SEA]

wikipedia is your friend (as long as there are references!!), break the word down into re - shimming. Its probably better to ask a gun doctor or someone with more experiance with this though

[freewheelin4eva]

a shim is something to take up some slack, for example the bushings or bearings in your gear box, you shim them so that they do not have excessive movement side to side. shim too tight things do not move too well, shim too loose and things tend to be sloppy, and wear out quicker, from what I hear the JG guns, come with plastic bushings, And are shimmed poorly. by the way how is your JG gun holding up? I have been thinking about getting one.

[aZn_triXta07]

All chinese guns have half-ass shim jobs, maybe a little too much grease and of course plastic bushings. If you've tinkered with a mechbox and you're a do it yourself kind of person you can easily pick up on this slack and have the gun preforming alot better than the manufacturer specifications.

[fergumanii]

If you want help with changing the internals, check out http://www.mechbox.com/site/ . I found that they have a little bit of info on reshimming (tips ect.) After watching a video or two I picked up a few tips on how to test the shim job.

[HellRanger]

Nothing beats experience.

Either dig into it with the help of a gun doctor or take chances, here is a hint, taking chances with your main battle rifle is not a good idea.

[Jimski]

Hello all,

here is my shimming technique, can you guys comment on it and tell me if it's any good?

Recently I added torque ups on my Aug.
So what I did is

1.take the mechbox apart, remove everything.
2.put on the metal bushings.
3.put on the torque-ups with no shim, close the gearbox.
(no screw, only the metal plate on top)
4.pinch each gear between my thumb and index ( on the exterior of the bushings then) and move it from side to side to have an idea of how much it moves - I begin with the sector gear.
5.take the mechbox apart and add shims:
large diameter for shim-to-bushing contact, small diameter for shim-to-gear contact.
I add thickness one side at a time, trying to:
-keep the sector gear centered
-keep the spur gear aligned with bevel and sector gears
(this usally means as low as possible)
-keep the bevel gear centered and rotating easily.
(this usually means thin shims but I guess it depends of the gear measurements)

close the box - check that it seals properly.

tell me!

[HellRanger]

I would suggest using at least 2 screws everytime you close the gearbox when checking the shimming (the one at the bottom of the gearbox in front of the motor and the second one from the back at the top of the gearbox).

There are faster technics than others, but the only thing that counts is the end result. Also putting the gearbox back together properly (including the right end of the sring over the spring guide) is very important. Again, it all comes down to experience.

Originally Posted by Jimski

Hello all,

here is my shimming technique, can you guys comment on it and tell me if it's any good?

Recently I added torque ups on my Aug.
So what I did is

1.take the mechbox apart, remove everything.
2.put on the metal bushings.
3.put on the torque-ups with no shim, close the gearbox.
(no screw, only the metal plate on top)
4.pinch each gear between my thumb and index ( on the exterior of the bushings then) and move it from side to side to have an idea of how much it moves - I begin with the sector gear.
5.take the mechbox apart and add shims:
large diameter for shim-to-bushing contact, small diameter for shim-to-gear contact.
I add thickness one side at a time, trying to:
-keep the sector gear centered
-keep the spur gear aligned with bevel and sector gears
(this usally means as low as possible)
-keep the bevel gear centered and rotating easily.
(this usually means thin shims but I guess it depends of the gear measurements)

close the box - check that it seals properly.

tell me!

[freewheelin4eva]

This makes me think of something, how do ya'll check for backlash?

[ILLusion]

Define backlash in the context of airsoft?

[ThunderCactus]

you dont lol
even if you had backlash, theres honestly nothing you can do short of machining yourself a new gearbox with new bushing positions.
Helical gears are shimming sensitive to remove backlash, I installed them in my G&P 249 and the bearings are close enough for the gears to mesh, but too far apart for them to be sensitive to shimming, can't remove the backlash.

[freewheelin4eva]

Well I am new to the world of airsofting, it was something that crossed my mind, I check backlash all the time, (rebuilding diffs and trannys), and there are helical gears in those. Buy shimming one side of the gear more, moves the gear closer or farther apart from the other, thus changing backlash. Of course we all know too much backlash = premature wear and stripping, too little = premature wear, stiffness/binding, and a inefficient gear train.