ProGear V.2 + Systema bushings = teh tight?

[Groombug]

So I'm sitting here with one and a half gearboxes-worth of parts, hoping to swap my upgraded internals from my stock TM gearbox to a ProGear gearbox. Disassembly went fine, but when I started to switch the gears and their bushings over to the new platform, the bushings don't fit. By this I mean they LOOK like 6mm bushing holes, but they don't fit my Systema 6mm oiless bushings. By don't fit I mean they don't just drop into place like they do on the old TM stock gearbox shell.

What is the problem here? Are my bushings warped (unlikely?) or is my ProGear a lemon?

[Mantelope]

I had trouble getting bushings into my progear when I got it new. Bushings are supposed to be tight on the mechbox; in some situations they move freely, but the really ought to be stationary. I'd recommend pushing them as hard as you can into the progear with something flat, but don't hammer, because you risk warping the mechbox. If you need to, sand or file out the bushing holes, but again, tight is good.

[concept_8]

Use a c-clamp to squeeze them in slowly.
I found an ics bushing swap I did to be tight too, and it worked well without risk of damage from pounding them in.
If need be you can tap them in with a hammer and a piece of wood or a wooden peg or something as a buffer.

[Mantelope]

A hammer's head can be pretty good, just don't actually hammer. If you have some circular support that you can put under the mechbox, around the bushing hole, you can use a tiny bit of momentum with the hammer. A friend installed bushings into an ICS M4, and used his hammer a little too much; he must have warped the mechbox because he ended up going through a set of gears and a motor every month.

[Tankdude]

freeze the bushings silly. Put them in the freezer for an hour or two.

Then push them in.

[Dirty Deeds]

That might work. When things freeze, they contract a little bit. Opposite of heating a nut to get it off, heat expands.

Try it.

[Groombug]

Wouldn't the freezing process warp my bushings?

[Tankdude]

no. it is a process used everywhere from machine shops to factories.

the bushings will go right back to normal.

[Mantelope]

Yeah, that's an excellent idea. I used the same method to get the front sight onto my SVI's metal slide.

[ILLusion]

i just use the butt of a screwdriver or....


a rubber mallet

and yes, it's suppose to be tight. tight is good.... really fucking goood... unnngnggggghhh.....

lol

tight....

[Groombug]

Froze them for four hours... nothing. Still don't fit... resort to brute force, shall I?

[ILLusion]

Resort to brute force, but make sure that you hammer them in with an object that ISN'T harder than them (to prevent damaging them), and make sure you get them in straight and not crooked.

btw, try freezing the gearbox along with the bushings... but if the bushings don't go into the frozen gearbox easily, DON'T hammer them in too much or something could crack.

[Groombug]

Rubber mallet then? How do i get them straight and not crooked? Visually guestimate and then try spinning the gears?

Could I try heating the bushing holes in hopes they expand enough for a cold bushing to be fitted in?

[ILLusion]

Rubber mallet. Do it by eye. Just make sure it's not severely crooked. I've seen some people seriously screw their stuff up by blindly pounding away when the bushing's at a 45 degree angle. totally senseless destruction of their toys.

Heating the bushing holes will make the hole diameter smaller.
You gotta freeze it to make them contract towards their centre of mass (ie, away from the centre of the hole), making the hole... larger.


But really, you don't need to go through that much trouble. I just bust my bushings in with:
a) rubber mallet
b) end of a screwdriver

On occassion, I may use a flatheaded punch for a precision hit to guide the bushing in.