Air rifle re-assembly, where to put grease?

[lewgun]

As above guys

My meteor will be going back together tonight after being rebuilt and de-greased

Where should I put the grease?

Cheers

Lewis

[Fred68]

What grease is as important as were!! The grease should be a Moly based grease. It needs to go on the spring but very sparingly, the spring guide and a tiny smear around the back of the piston! You really don't need much at all. !!

[Fred68]

Oh and a bit on the cocking shoe and slot !!

[lewgun]

Ok thanks mate

What about in the main cylinder?

I test fitted the piston head with the new seal in it the other day and it would barely go in, let alone come back out!!

I have some grease at home originally intended for my bike forks, I was going to use that but looks like I might need to re-think

[Gwylan]

What's the inside of the cylinder like? any scratches or rust? If it's not bright and shiny, it could do with smoothing out with wet and dry, a polish with chrome polish, and degreasing again, then treat with a moly liquid, or aerosol. (like DriSlide.) If it's a plastic piston seal, just a smear of SM50 around the edge, some LT2 grease on the rear of the piston, and the rear spring guide. If the guide isn't a tight fit, smear a little LT2 on the spring itself to reduce twang. Put a bit of grease around the barrel hinge, and lock up.
With grease, less is best, don't overdo it. Even with a light lube, it may diesel a bit at first.

Gus

[Fred68]

Ok thanks mate

What about in the main cylinder?

I test fitted the piston head with the new seal in it the other day and it would barely go in, let alone come back out!!

I have some grease at home originally intended for my bike forks, I was going to use that but looks like I might need to re-think

The grease needs to be Moly which is black and used in car CV joints !! Most piston seals need accurate sizing to the cylinder!! (Except the O ring type or leather type) You can gently sand them to the correct size. You want it sized so it will just stick in the cylinder under it's own weight but move if pushed with a finger. Honing the cylinder will also help the piston to bed in faster and allow more power from a give pre-load and on NO account put grease in the cylinder as it will grease it's self in use !!

[lewgun]

It's definately not shiney mate

Maybe i need to get a but of wet and dry on the inside of it but how i'm going to do that though beats me!

It's not just a tight fit, I mean really tight, like it felt like it was destroying the new seal as I was pushing it in. As it is, I doubt even the force of the spring could cycle the piston

I've got to have gone wrong somewhere surely?

Oh, and it a brand new seal, direct replacement from chambers, surely shouldn't need modifying to fit?

[Nessmuk]

Ok thanks mate

What about in the main cylinder?

I test fitted the piston head with the new seal in it the other day and it would barely go in, let alone come back out!!

I have some grease at home originally intended for my bike forks, I was going to use that but looks like I might need to re-think

You definitely want to size the piston seal. I rebuilt my HW97 a little while back without sizing the piston seal and it was quite down on power, consistent but down. I was advised on here to size the seal so that's what I did. I'm fortunate enough to have a lathe so it was easy to do. I sanded mine using 600 grit wet and dry taking a little off and then trying it for size. Alternating sanding and test fitting until it only took a little push to get it moving took a while but made a big difference. You want no grease at all in the compression chamber or it will diesel.

I also ended up going from having to space the spring to needing to cut it down to keep the power under 12ftlb!

Simon.

[Fred68]

It's definately not shiney mate

Maybe i need to get a but of wet and dry on the inside of it but how i'm going to do that though beats me!

It's not just a tight fit, I mean really tight, like it felt like it was destroying the new seal as I was pushing it in. As it is, I doubt even the force of the spring could cycle the piston

I've got to have gone wrong somewhere surely?

Oh, and it a brand new seal, direct replacement from chambers, surely shouldn't need modifying to fit?

First up is the seal leather or synthetic ? If it's leather then the inside of the cylinder should be shiny. If you have a parachute synthetic seal then the cylinder bore needs to be honed in a cross hatch pattern!! Then the seal needs to be reduced in size to fit as I described earlier

[Fred68]

It's definately not shiney mate

Maybe i need to get a but of wet and dry on the inside of it but how i'm going to do that though beats me!

It's not just a tight fit, I mean really tight, like it felt like it was destroying the new seal as I was pushing it in. As it is, I doubt even the force of the spring could cycle the piston

I've got to have gone wrong somewhere surely?

Oh, and it a brand new seal, direct replacement from chambers, surely shouldn't need modifying to fit?

All synthetic seals need accurate sizing to the cylinder they run in, exactly like they would in an engine

[lewgun]

Right, this is becoming alot more complex than i first thought- so I need to re-hone the inside of the main cylinder and also modify the direct replacement seal to make it fit?

Any ideas on how to go about this?!

[lewgun]

Oh and it is synthetic, not leather

[Bad Beagle]

Hi - there is a fantastic guideon here written by Hssing See, I think it may even be a sticky now. I followed it to the letter to tune a Gamo a few years ago -it has everything you need to know.

good luck and don't get Moly on the leather sofa - like I did !

[lewgun]

Guys, surely this cant be right?

I have searched and searched and cant find anyone who has had to rehone just to replace the piston seal unless they are "tuning" their rifle?

Maybe I should just stick the old seal back in?

[Fred68]

A cylinder hone is a surface preparation done to give the new seal the best possible chance to bed in correctly !! It's not going to damage the the seal if you don't hone unless there is some damage to the cylinder surface that could damage the new seal which is why I always hone first
Here is how I do it !!
http://ukchineseairgunforum.myfreefo...bout20260.html