In seal fitting, how tight should the replacement seal be?

In seal fitting, how tight should the replacement seal be?

Joined: October 25th, 2002, 3:46 pm

October 15th, 2006, 8:19 pm #1

Wishing to replace a seal I am curious as to how tight the seal should be? Is there a way to quantify that tension? Any comments or instruction appreciated.
I have a BAM XS B20 that I wish to use a Quest seal for as I have one on hand.
Thanks to all in advance.
Walter....
BTW I am aware this is Gamo guys but the procedure is likely very similar to using Quest parts in a Gamo eh?!
Cheers,
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Joined: February 14th, 2006, 4:12 pm

October 15th, 2006, 11:25 pm #2

it with a piece of 1/4" tubing. Cock gun. Push one end of tube tight onto barrel. Blow into tube and listen for air leaks.
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Joined: February 27th, 2004, 4:38 am

October 16th, 2006, 12:53 am #3

Wishing to replace a seal I am curious as to how tight the seal should be? Is there a way to quantify that tension? Any comments or instruction appreciated.
I have a BAM XS B20 that I wish to use a Quest seal for as I have one on hand.
Thanks to all in advance.
Walter....
BTW I am aware this is Gamo guys but the procedure is likely very similar to using Quest parts in a Gamo eh?!
Cheers,
with the new seal installed. Maybe 1 to 2 lbs of effort to push the piston into place. Can be a little tighter if you don't mind it having to wear in for a while.
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Joined: October 25th, 2002, 3:46 pm

October 16th, 2006, 3:27 am #4

Made up a sizing sleeve bored to the chamber id. with the seal in the sleeve (slightly oily) it moves at 10#sforce. In the chamber (dry) it takes 15 pounds to move the seal. I looked to fit the sleeve so well that I made no changes to its size until I shoot it some. I will chrony tomorrow as it sure seems hotter and less jarring firing it. I think that a lot of the jolt I was getting may have been due to blowby/leaky seal.
Will post results tomorrow.
Walter.....
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Joined: October 21st, 2001, 3:36 am

October 16th, 2006, 3:36 am #5

Wishing to replace a seal I am curious as to how tight the seal should be? Is there a way to quantify that tension? Any comments or instruction appreciated.
I have a BAM XS B20 that I wish to use a Quest seal for as I have one on hand.
Thanks to all in advance.
Walter....
BTW I am aware this is Gamo guys but the procedure is likely very similar to using Quest parts in a Gamo eh?!
Cheers,
it may take a while to wear in. 500 shots? I'll watch for your results.

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Joined: October 25th, 2002, 3:46 pm

October 16th, 2006, 5:49 am #6

so I will shoot it like this and then try for say half the tension, repeat test and then go for say 3or so #sforce. Might be interesting data if it is repeatable. I can order some seals to see what happens if I overshoot the best efficiency.
Thanks Lon
Walter.....
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Joined: February 27th, 2004, 4:38 am

October 16th, 2006, 1:56 pm #7

Made up a sizing sleeve bored to the chamber id. with the seal in the sleeve (slightly oily) it moves at 10#sforce. In the chamber (dry) it takes 15 pounds to move the seal. I looked to fit the sleeve so well that I made no changes to its size until I shoot it some. I will chrony tomorrow as it sure seems hotter and less jarring firing it. I think that a lot of the jolt I was getting may have been due to blowby/leaky seal.
Will post results tomorrow.
Walter.....
First and most obvious is it's gonna detract from power. Just as a rough guestimate figure 3" stroke length (1/4ft) times 10lbs comes out to 2.5 fpe loss of power. That in itself might make the gun feel smoother. The other thing, is with a tight seal you may get too much "squeegee" effect and scrape most/all the lube off the sides of the comp tube. Just pay attention to things while wearing in and watch out for a squeaky seal.
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Joined: February 12th, 2006, 4:58 pm

October 16th, 2006, 2:29 pm #8

Wishing to replace a seal I am curious as to how tight the seal should be? Is there a way to quantify that tension? Any comments or instruction appreciated.
I have a BAM XS B20 that I wish to use a Quest seal for as I have one on hand.
Thanks to all in advance.
Walter....
BTW I am aware this is Gamo guys but the procedure is likely very similar to using Quest parts in a Gamo eh?!
Cheers,
I was told by I believe RBest that there should be .003 compression. So the seal should be .003 larger than the compression tube.

Their are no problems, just opportunities for a solution.
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Joined: May 2nd, 2006, 4:27 am

October 16th, 2006, 3:36 pm #9

Wishing to replace a seal I am curious as to how tight the seal should be? Is there a way to quantify that tension? Any comments or instruction appreciated.
I have a BAM XS B20 that I wish to use a Quest seal for as I have one on hand.
Thanks to all in advance.
Walter....
BTW I am aware this is Gamo guys but the procedure is likely very similar to using Quest parts in a Gamo eh?!
Cheers,
if the seal is too tight it just takes an extended time to break in, .003 to.004 oversize is about right. The ring on the inside of the seal traps air and expands the seal on pressure build up in the compression chamber so there is no need to have a large oversize in the seal.

Understand the seal gets it's lube every time you cock the rifle the seal lubes itself with the lube on the O.D. of the comperssion tube.

How does the lube get there you ask ? when you fire the rifle the lube is forced to the seal by the stopping of the piston, and the lube not being attached to anything spreads its self on the seal. This is why a rifle will diesel if you go overboard with lube when you assemble the rifle, lube will bypass the seal and get into the compustion chamber.

Also on Gamo rifles and the clone's the seal cap on the end of the piston is Crimped on not welded so if someone goes overboard with spring tar it collects in the forward end of the piston and adds to the already lube there.

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Joined: October 25th, 2002, 3:46 pm

October 16th, 2006, 3:38 pm #10

I was told by I believe RBest that there should be .003 compression. So the seal should be .003 larger than the compression tube.

Their are no problems, just opportunities for a solution.
I'll go search for it.
0.003" fit is a long ways from where I'm at for sure.
Thanks for the info
Walter.....
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