G&G rebuild - protruding bearing!

[DanBow]

So, I finished work early this morning and rather that go straight to bed I got on my hands and knees to look for the missing anti reversal latch spring from Wednesday afternoons shenanigans. Much to my surprise I found it in the exact place that I had looked when I first lost it! 

So, all rebuilt, which is great but I didn't need to purchase a complete gearbox spring set and gearbox clip, but I now have a different issue! I shimmed it but a couple of the bearings now protrude out of the gearbox. One of them is causing an issue that it sits underneath the safety selector switch and interferes with it. It protrudes by 1.12mm

 

 

I've had a look but you don't seem to be able to get thinner bearings so what do you suggest? Admittedly, I haven't played with it properly and it might be fine but I'll have another look later on after some much needed sleep. 

Edited April 19 by DanBow

[The_Lord_Poncho]

I'm thinking that is only possible if the bearing is physically reversed? It's a while since I changed any bearings in a gearbox, but from memory they are 'lipped' so can't push through the holes in the gearbox casing like that, unless you've inserted it from the wrong side of the shell (or the holes in the gearbox case are massively enlarged/rounded off from a previous seized bearing).

[DanBow]

you're right, they are lipped so will only go in one way, it's an almost new rif so no massive wear and tear and they are a snug fit anyway. I've just seen that there are low profile bushings but, to my mind, that's a backwards step going from bearing to bushings? Unless I do just the one? I don' know.

[Sewdhull]

Are all those bearings the same width? I use some 3x8x3 bearings and they do protrude and the one under the selector plate needed the plate relieving, but yours look wrong. One flush and one not is weird. i think you'll need to open it up again...

 

https://simplybearings.co.uk/shop/Bearings-Deep-Groove-Ball-Bearings/c3_11/index.html?selection=Flanged+Ball+Bearing

 

Select 3mm ID and you'll see 2, 2.5, 3 and 4mm widths.

 

 

[Lozart]

1 hour ago, DanBow said:

I've just seen that there are low profile bushings but, to my mind, that's a backwards step going from bearing to bushings? Unless I do just the one? I don' know.

 

It really isn't, in our application especially. Good bushings are always going to be better than cheap bearings anyway.

 

1 hour ago, Sewdhull said:

Are all those bearings the same width? I use some 3x8x3 bearings and they do protrude and the one under the selector plate needed the plate relieving, but yours look wrong. One flush and one not is weird. i think you'll need to open it up again...

 

https://simplybearings.co.uk/shop/Bearings-Deep-Groove-Ball-Bearings/c3_11/index.html?selection=Flanged+Ball+Bearing

 

Select 3mm ID and you'll see 2, 2.5, 3 and 4mm widths.

 

 

 

What he said.

 

Take it apart and check to see if all the bearings you have are actually the same thickness.

[Colin Allen]

That does look very wrong; the bearing should really not interfere that much with the selector plate.
 

Unless you are building a super high speed gun, good quality bushings are probably preferable to the cheap and nasty bearings usually used in airsoft guns.

[ak2m4]

Looks to me like you've fitted a 3mm wide bearing under the selector plate but a 2.5mm on the bevel gear.  Ideally you need 2.5mm bearings.  You can fit 3mm, in fact EZO (3x8x3) get their extra strength from being 0.5mm wide.  EZO do 2.5mm wide but the set I tested exploded. 

 

Can you measure them?

 

[DanBow]

Just now, ak2m4 said:

Looks to me like you've fitted a 3mm wide bearing under the selector plate but a 2.5mm on the bevel gear.  Ideally you need 2.5mm bearings.  You can fit 3mm, in fact EZO (3x8x3) get their extra strength from being 0.5mm wide.  EZO do 2.5mm wide but the set I tested exploded. 

 

Can you measure them?

 

Last night shift tonight so I'll pull it apart at the weekend and measure everything. 

[DanBow]

Ok, I really shouldnt be having a look as I dont have a good track record of doing things when I'm on nights . . . 

 

 

 

but 

 

 

 

 

Ive just pulled the selector plate off and the underside is already recessed in the two areas that sit over the bearings.

 

I'm going to leave it for now and put it all back together properly over the weekend and see how it goes. 👍

[Pseudotectonic]

Weird

 

It looks to me it will still interfere because the groove on your selector plate doesn't look deeper than the 1.12 mm that you need, because the upper surface is supposed to be touching the gearbox surface when installed, so the grooves need to be deeper than your protruding bearing to go over it

 

But, you can just swap the bearings around, put the thicker one below and the thinner one above, problem solved

 

And just to check, you haven't inserted the bearings from the outside, right?

[DanBow]

Just now, Pseudotectonic said:

And just to check, you haven't inserted the bearings from the outside, right

 

Nope, inserted the right way.

 

I did continue to play with it before i came to work and the selector does sit flat ish on the gearbox.

 

 

I've put it back in the reciever and, apart from forgetting to put the selector spring back in, it selects fine. I'll finish it off when i get up tomorrow and report back.

[DanBow]

Right, I'm enjoying this home teching malarky but there is so much to learn. Like not all springs are equal. Like not equal in length!!! I suppose common sense should have told me that a longer spring, even though a lower rating, would make it more spicy than the standard m110 spring! Who knew that G&G use a shorter main spring? Well, I did actually when the seller told me! But did I realise the implications of that! No. Well I did but it was after I had bought the new spring and wanted to get it put together. Impatient? Me? Absofuckinglutely!

 

Anyway, got it all put together and it shoots lovely. The protruding bearing is not an issue at all.  My delivery of parts from @ak2m4 just came and although I am very happy with the service and cost, I didn't need it but will definitely being using him again. Thanks Pete.

 

So, no pics this morning but while I start searching for springs in 160mm length, can anyone point me in the direction of some? 

 

Oh, I'm probably going to take the new spring out and cut 10mm off the end. Got nothing to lose at this point!

 

 

[Shamal]

Oh, I'm probably going to take the new spring out and cut 10mm off the end. Got nothing to lose at this point!

 

I've read on here that if you cut springs you have to flatten the end. Not sure how you would do that. Maybe a Dremel? Or perhaps heat and a hammer?

 

[DanBow]

4 minutes ago, Shamal said:

I've read on here that if you cut springs you have to flatten the end. Not sure how you would do that. Maybe a Dremel? Or perhaps heat and a hammer?

 

Yes, me too. I've got heat and files so I think I'll cut it with my hacksaw and file it or cut it, heat it and hammer flat. 

[Pseudotectonic]

In my case I've actually tried heated up one end of the spring (with 4-5 coils compressed with a pliers) and aimed a heatgun at it at 500C for like 10 seconds, and held it for a minute or two until it cools down, and after it cools down it keeps its shape in the compressed form (had to do several passes to get the shape right because of pliers being uneven and to get the FPS down enough)

 

I ended up able to reduce the overall length from ~170mm to ~155mm and bring down my FPS from ~355 to ~340 which is hopefully more chrono friendly

 

So yeah, heatgun worked for me, no cutting, and you can fine tune it gradually if you do it in several passes

 

The ends are still flat, there was some very minor surface oxidisation which I buffed out with sandpaper, but the original end coil flats are still there

[DanBow]

1 minute ago, Pseudotectonic said:

In my case I've actually tried heated up one end of the spring (with 4-5 coils compressed with a pliers) and aimed a heatgun at it at 500C for like 10 seconds, and held it for a minute or two until it cools down, and after it cools down it keeps its shape in the compressed form (had to do several passes to get the shape right because of pliers being uneven and to get the FPS down enough)

 

I ended up able to reduce the overall length from ~170mm to ~155mm and bring down my FPS from ~355 to ~340 which is hopefully more chrono friendly

 

So yeah, heatgun worked for me, no cutting, and you can fine tune it gradually if you do it in several passes

 

The ends are still flat, there was some very minor surface oxidisation which I buffed out with sandpaper, but the original end coil flats are still there

That's a good shout. I might try that before cutting. 👍

[Rogerborg]

42 minutes ago, Shamal said:

I've read on here that if you cut springs you have to flatten the end. Not sure how you would do that. Maybe a Dremel? Or perhaps heat and a hammer?

 

[Much typing deleted, I just do this]

 

 

I'd stress being careful to heat only the last coil, and just enough squish it, as the heating will de-springify it. If you only want to lose a small bit of energy, you can just heat and squish a coil without cutting it at all.

 

[EDIT] Right, basically what @Pseudotectonic said.

[Colin Allen]

48 minutes ago, Shamal said:

Oh, I'm probably going to take the new spring out and cut 10mm off the end. Got nothing to lose at this point!

 

I've read on here that if you cut springs you have to flatten the end. Not sure how you would do that. Maybe a Dremel? Or perhaps heat and a hammer?

 

Holding the spring with a pair of pliers, heat up the cut end and, when it is glowing orange, press it down against a metal surface.

[Sewdhull]

A certain rated spring takes into account the length of the spring to arrive at the strength the spring will be used at.

 

For example you can increase the strength of a spring using spacers to pre-compress it or it can be longer than another spring with same spring constant which ends up pre compressing it when installed. In fact all the springs seems to have a degree of pre compression when installed.

 

For springs that are the same length they need to be stiffer, thicker wire or some such. Looking at the springs I have what seems to happen is that some springs are just longer than an otherwise identical spring, until you need to use a stiffer material because you'll run out of room to compress it.

 

Springs are cheap enough, I wouldn't bother cutting one. Take off a bearing at the guide end if you have one on the cylinder head perhaps, you don't need 2 bearings.

Edited April 20 by Sewdhull

[DanBow]

Only got one bearing.

 

 

Would removing a mm or 2 make that much difference? I'm looking at shortening my spring by about 17mm? I need to drop about about 20fps.

 

Really grateful for all of your input too. 😁

Edited April 20 by DanBow

[DanBow]

34 minutes ago, Sewdhull said:

Springs are cheap enough, I wouldn't bother cutting one

 

Just an afterthought, G&G use 160mm springs but every aftermarket one seems to be 175mm. Unless I fit something like an M80 and hope that with it being compressed to 160mm makes it equivalent to an M100/90/95. I don't think the actual spring rating is that important as long as it's at the right fps. Not sure if rate of fire would be changed with it being a "weaker" spring but, again, will compressing it not affect that????

 

My head is about to fall off! I'm going for coffee!

[Sewdhull]

Do you have a bearing on the cylinder head? If so you don't need the one on the spring guide. I cant recall how much i lost, ill go hunt down the post

 

[DanBow]

2 minutes ago, Sewdhull said:

Do you have a bearing on the cylinder head?

No.

[Sewdhull]

Ultimately the thing that determines the strength of the spring is the force needed to compress it when installed and compressed in the cylinder.

 

You can have a long weak spring that gets pre compressed on installation and will be the same rating as a short strong spring which gets pre compressed less. They are all of similar length with variations of up to 25mm from those I have.

2 minutes ago, DanBow said:

No.

Then that option is not available to you.

 

It's not the length that matters but how it's used.

I bought a selection of AKs springs when I was trying to get the right fps on the MP5

[Pseudotectonic]

Just to add a note about the heatgun method, if I were to do it again I would do it in the middle part of the wider coil section (see image below)

 

And I wouldn't make the spacing narrower than the existing narrow parts

 

Because I did it on the narrow coils side and now when it compresses those coils can "bottom out" which I suspect is causing some very minor ringing noise after each shot (probably harmless, or maybe not even related)

 

And if you do it in the middle section you won't oxidise the end coils flats (easier to clean up in middle) nor bottoming out the end coil

 

And you will minimise the changes of any coils "bottoming out" by keeping some minimum spacing