seal replacement

[Muppit]

for all of you who do seal replacements, what is the best way to reinstall the seal on the piston and get it back in the compression tube undamaged

[Kirk B]

Getting the new seal installed on the piston can test your patience. The last 2 I did, I heated them gently with a hair dryer to make them pliable, stuck it on the button on the end of the piston the best I could and then pressed it hard on a clean flat surface while turning the piston. I put the slightest bit of lube on the inside of the seal to help it go on and was sure to wipe off any excess once I was done.

As far as reinstalling in the tube, I just made sure to debur everything the seal could get snagged on before putting it back in. Unless you have a threaded end cap like on the Trail XP's, that's all you should have to do I would think.

[Mark 611]

ya you need to deburr the cocking slot area if your not going to do a full tune on the rifle, the internal areas are sharp from the milling process of manufacture of the tube and you'll cut the seal or nick it up if you don't correct this, I personally do not twist or turn the piston when I install it back into the tube cause if their is a burr your gonna tare up the whole seal, you need to get a ball {flex hone} with at least a 320grit to go in and do the job of beburring this area JMHO.

[Kirk B]

I personally do not twist or turn the piston when I install it back into the tube cause if their is a burr your gonna tare up the whole seal,

Just to be clear, I was talking about turning the piston just to get the seal installed on it. Agreed there's no need to twist it when you're putting it back into the tube.

you need to get a ball {flex hone} with at least a 320grit to go in and do the job of beburring this area JMHO.

You can also use a split dowel with wet/dry sandpaper or emery and use a piece of plastic cut from a bottle as a backer ala daved. I'll see if I can find the pic he posted a while back.

Edit: Found it. Go to the 3rd post in this thread:
http://www.gatewaytoairguns.org/GTA/index.php/topic,7320.msg59900.html#msg59900

[Rocker1]

 What kind of air gun are you speaking of? all are not the same. Thanks David

[Muppit]

its a crosman g1 extreme its all worn out from not being mantained so i will be doing a lot of work to it rite now im deburing what needs it, its prettty polished just from use but the tube needs a hone and i debured the cooking slot with a jewlers file may go over it with 2000 grit wet dry paper though

[uncle paulie]

2k grit is a bit fine for steel, 400 would do, if you're going to hone, just hone the compression chamber. If you allow the hone to come up into the "slot" area, the slots will eat your stones. Use the 400grit ala David above for the back of the tube.

pv

[Muppit]

2k grit is a bit fine for steel, 400 would do, if you're going to hone, just hone the compression chamber. If you allow the hone to come up into the "slot" area, the slots will eat your stones. Use the 400grit ala David above for the back of the tube.

pv

was going to go over cocking slot with 200 grit not do a hone that would pretty much polish the tube back to were it is now but u say use 400 on tube i'll do that u got more experiance then i

[anuthabubba]

"Edit: Found it. Go to the 3rd post in this thread:
http://www.gatewaytoairguns.org/GTA/index.php/topic,7320.msg59900.html#msg59900"


Now that is about the neatest home grown spring compressor and hone I've seen.

[Muppit]

thanks anuthabubba i have a compressor

[uncle paulie]

Your prior post said 2000 grit, I'll guess that was a typo, 200 grit would be fine near the cocking slot. If you're going to hone the compression chamber with a hone, make sure the metal the stones are adhered to does not protrude past the stones, otherwise, you will not hone the very end of the chamber and you'll have a problem with the seal. It will eventually not be large enough to give  max power as the seal will eventually take the size of the end of the chamber which will be smaller than the rest of the chamber.

pv

[Muppit]

uncle pauly i was going to use a sloted dowel and emery paper for the compression tube my smalist hone only goes to 1.5 inch i generally work on cars and smal engines not ag's

[Mark 611]

a 1-1/8in will work if its a flex hone

[uncle paulie]

I'd wait and get a brake cylinder hone, Auto Zone carries them in stock, but a lot more expensive than Harbor Freight. I'm sure you could find on in one auto parts store or another. Likely $14-15. You'll also need a drill bit extension or other device to add length to the shaft to get it deep enough. Just remember to file down the metal tips on the stones.

pv

[mikeiniowa]

If you want to try it you can do it the hard way.....slide seal only down the tube sideways turning it get past all the cut outs, once past the last one turn it so it faces the right way and push it to the front of the cylinder. Using a dry type lube on the mushroom on the piston then push piston into the tube and let it slide until it rests on the back of the seal. Using a piece of thick wall tube or smooth pipe push the piston onto the seal with a compresser or hit the end of the tubing with a hammer to pop the seal onto the piston. They use this method at the factory for some rifles...