Is this seal no good?

[avidairgunner]

Hey everyone, I was in the process of tuning my Quest and after deburring everything, or I thought was everything. I started pushing the seal into the receiver and right before I thought everything was good, I nicked the seal at the bottom right where the cocking arm goes into the receiver. My question, is this JM Apex seal gone? Here are the pics.

[DanoInTx]

I'm no expert, but one should be along shortly.  Having said that, if it was mine I would replace it and deburr the area of the compression tube really well that caused that so I didn't do it again.  Hth,

[SDale]

Yup. Time for another one.

You maaaaaaay be able to size the seal down if it's a really tight fit, and still be able to use it. But the looks like a pretty big chunk that was taken out.

[mikeiniowa]

if you shot it for very long it would burn through.................

[avidairgunner]

I figured the damage was too much. I guess I gotta take a bite of $18 to have another one.

[avidairgunner]

mikeiniowa - 8/8/2009  12:18 AM

if you shot it for very long it would burn through.................

What do you mean by burn through? As in it will go bust? I am guessing the same if that is what your mean

[tjk]

Has, the seal is toast. Next time try taking a wooden match or anything similar, and press the seal where it is exposed through the chocking slot,  the cross bolt, etc. If your reciever/action has a scope stop hole machined into it,...be a good idea to deburr that as well (on the inside). You just need to press the end of the seal enough for it to by-pass these areas. Good Luck, tjk

[TCups]

"What do you mean by burn through? As in it will go bust?"
____

The rapid, high compression stroke of a springer superheats the compressed air at the business end of the piston.  The failure of the seal at the weak point will be from very high temperature compressed gas pushing through the weak spot, quite literally burning the plastic seal where the leak is, and thus worsening the defect with every shot until the seal fails.  Additionally, on the cocking stroke, the defect in the seal lets excess lubricant escape into the compression chamber, so the dieseling is worse and the damage is accelerated.  For the work involved in tearing down, tuning, and lubricating a springer, it makes no sense to put one back together with a damaged seal.

[mikeiniowa]

I have been looking for a very thin wall tube, kind of like beer can thin. Slide the piston and seal in backwards to keep from boogering the seal then slide the whole assembly into the reciever until it's past all the cut outs then push the piston out of the tube and pull the tube out. No nicks that way even if you happen to miss a spot deburring. Would also be great at the factory to keep the factory seals in one piece...

[tjk]

I've thought of something close to what you've said Mike,...never persued it though. Has, you might try this method as well. Next time you attempt to install the piston with a new seal, place the action in a spring compressor. This way you'll have a free hand to set the piston. You may have to put an extention on the push rod and a peice of wood or plastic on the end of it so as to not damage the pistons inside top hat seat. Ive never experienced alot of burring in the cross bolt holes of the action,...but when you get around the slotted areas you need to be real careful,...be it de-burred or not. Slowly push the piston in with one hand cranking the spring compress, and with a wooden dowel/match stick, slightly press the front edge of the seal through the cut-out areas. You don't have to press the seals front edge very hard,...just enough to by-pass the slot and where the trigger assembly slides in. Once you get the seal passed this area, you're home free!!!! Best of Luck, Thomas

[avidairgunner]

Thanks for the guidance everyone. I really like the idea of using a spring compressor and a dowel. The way I was doing it was my taking a dowel and slowly tapping the piston and everything was fine because I would push the lip of the seal where ever it would stick out from the cocking slot area. Finally when I thought that I had everything going well I pushed the piston a little too hard and did not push down on the seal lip sticking out right where the cocking slot has a round area to insert the cocking arm. That is where the seal got nicked.

However, that wont happen again. Because you guys have helped me and also because I will make sure to deburr that area really well and take things slow.

Btw, I did deburr all the other areas including the hole for the scope stop. Those areas were nice and smooth and didnt give me any trouble. However, the area that I completely forgot was the one that damaged the seal. You live and learn I guess

[avidairgunner]

Hey tjk, I received your PM. However, for some reason I am not able to send a PM to anyone. The message stays in the outbox......what is up with that?

[mikeiniowa]

has to be opened by reciever to get out of the box...

[avidairgunner]

Thanks mike

[kiwi]

Thats the only way I instal a new seal....
what I use is a length of .15mm plastic shim
25mm wide....... tape the shim around a length
of tube / pipe ..then heat it with a hot air gun to put a
slight bow in it......
Slide it in the tube over the slot...slide the piston &
seal in and once pased the slot with draw the shim..
Don't use brass or stainless shim the sides cut the seal...

 Ps...    .1 shim would be better...but I an't got any in plastic..

Pete