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Thread: Sizing seals in springers

  1. #46
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    Quote Originally Posted by Vernal View Post
    I am using an AA seal,new from Chambers, but it is still much tighter than it seems should be. I had the same problem problem when I carried out your "simple tune " on my LGV,and you were kind enough, correctly, to point out then that the trouble was likely to be a tight seal. Resizing the seal, very time consuming, completely solved the problem, which is what caused me to start this thread in search of the best way to resize a seal. Nick G is kindly going to send me a run in seal which should confirm that the seal is the problem, or tell me to look elsewhere.
    I'd completely forgotten about your LGV, but my gut feeling is still that your TX issue could well be air leakage.

    True, AA seals do self size with use. With this thread in mind, I measured a brand new one on a piston today at 26.1mm diameter, against a worn but fully functional example at a little over 25.5mm. However, I have fitted brand new seals to TX200 pistons, and never had the muzzle energy issue you have experienced as a result, which is why I would be looking elsewhere.

  2. #47
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    My favourite read dropped through the letterbox on Tuesday, Jim. Your latest scribings on the LGV will, I'm sure, be the usual excellent fix of enlightenment that I'm very much looking forward to.
    THE BOINGER BASH AT QUIGLEY HOLLOW. MAKING GREAT MEMORIES SINCE 15th JUNE, 2013.
    NEXT EVENT :- May 4/5, 2024.........BOING!!

  3. #48
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    Quote Originally Posted by BTDT View Post
    True, AA seals do self size with use. With this thread in mind, I measured a brand new one on a piston today at 26.1mm diameter, against a worn but fully functional example at a little over 25.5mm. However, I have fitted brand new seals to TX200 pistons, and never had the muzzle energy issue you have experienced as a result, which is why I would be looking elsewhere.
    yeah, likewise.. I'm not sure I've ever had to size a std AA seal... Unless this is a particularly tight comp tube (or has leaks).

    Mr V, just another thought - have you tried sliding the piston down the tube without the seal fitted, to make sure it's not a tight front bearing, or the piston itself, that is the problem ?

    HTH - JB
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  4. #49
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    I will second Jim's thought that there may be an air leak elsewhere. I had a Mk1 TX that, when I bought it, was running about 9.5. I gave it a service with new spring, piston seal etc etc and it was still around 9.5. Extra preload made no difference. Tried a stronger spring ... no difference. No matter what I did it was always low. Then I turned my attention to the compression tube end plug. Outwardly Ok, it turned out to be the culprit. Once sealed correctly, power issues disappeared and all was well with the world.
    Might be worth a look. The O ring on the compression tube is 1.6 x 22.1mm if of interest.

    Cheers, Phil

  5. #50
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    Quote Originally Posted by TonyL View Post
    My favourite read dropped through the letterbox on Tuesday, Jim. Your latest scribings on the LGV will, I'm sure, be the usual excellent fix of enlightenment that I'm very much looking forward to.
    Hope you enjoy it, Tony.

    Quote Originally Posted by Shed tuner View Post
    yeah, likewise.. I'm not sure I've ever had to size a std AA seal... Unless this is a particularly tight comp tube (or has leaks).

    Mr V, just another thought - have you tried sliding the piston down the tube without the seal fitted, to make sure it's not a tight front bearing, or the piston itself, that is the problem ?

    HTH - JB
    I cannot remember ever sizing an AA seal, either, Jon.

    Mr. V, yet another thought. It's worth checking that there is no gap, however small, between the front face of the compression tube and the read face of the hexagonal section of the end cap. It is extremely rare, but not entirely unknown, for the end cap to start to unscrew.

  6. #51
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    Quote Originally Posted by Shed tuner View Post

    Mr V, just another thought - have you tried sliding the piston down the tube without the seal fitted, to make sure it's not a tight front bearing, or the piston itself, that is the problem ?

    HTH - JB
    Yes, I did try that, just to check that the new bearings were not causing a problem.
    My main reason for thinking that there is no problem with leaks elsewhere is that the gun was doing 11.3 before I changed the piston assembly. When I strip it to fit the used seal I will check all the other possible problems suggested by you and other contributers to this thread.

  7. #52
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    One more thing to consider , measure the stroke in the rifle, that piston was one I had in a box of bits , I didn't measure bit before I sent it 🥴, you never know, the rod may be long .

  8. #53
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    Quote Originally Posted by Vernal View Post
    Yes, I did try that, just to check that the new bearings were not causing a problem.
    My main reason for thinking that there is no problem with leaks elsewhere is that the gun was doing 11.3 before I changed the piston assembly. When I strip it to fit the used seal I will check all the other possible problems suggested by you and other contributers to this thread.
    OK, not bearing or piston then. The fact that it was doing 11.3 doesn't really help analysis, as the Mk3 stroke is capable of over 17 FP, so could easily hide a leak and still have power left over.
    Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.

  9. #54
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    Any joy yet, Michael?
    THE BOINGER BASH AT QUIGLEY HOLLOW. MAKING GREAT MEMORIES SINCE 15th JUNE, 2013.
    NEXT EVENT :- May 4/5, 2024.........BOING!!

  10. #55
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    Quote Originally Posted by TonyL View Post
    Any joy yet, Michael?
    I believe he is still waiting on the seals I sent him Tony.

  11. #56
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    Sadly the seals failed to arrive, lost somewhere by the Royal Mail I suppose, so today I did a bit more work on my own seal (following good advice from Nick) and got it to a fairly easy sliding fit, not falling under its own weight, but not needing much of a shove. With 47mm of preload i am now getting 10.9, which is pretty much where I like to be, and it is shooting very nicely - in fact it is now almost as good as my LGV -and you know how i love that Tony!

  12. #57
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    Yes, and extremely nice is that LGV, Michael.
    THE BOINGER BASH AT QUIGLEY HOLLOW. MAKING GREAT MEMORIES SINCE 15th JUNE, 2013.
    NEXT EVENT :- May 4/5, 2024.........BOING!!

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