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Thread: Crosman seals & pump cup

  1. #1
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    Crosman seals & pump cup

    Just been looking for a seal kit & pump cup for a Crosman 1377. An auction site has seals for around £6.00 & a popular supplier does pump cups for around £8.50 another source does a full kit for around £40.00. Doe anyone know what the lower cost ones are like? Or are the pricier ones that much better in terms of durability/performance?

  2. #2
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    Contact ped on here for advice,great guy.

  3. #3
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    Thanks for your reply, but I dont know how to make contact with ped, have you any details please ? Cheers

  4. #4
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    If SD Custom Design is still on the go, check out the prices on his site.

    Also look on the G-Mac site.

    ASI would supply directly until a few years ago. I don't think they do nowadays. But if you get the parts numbers from the excellent resource on the Crosman site they will supply them to your local ASI / Crosman dealer.
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  5. #5
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    my 1377 could not be pumped up .....stripped and found it to be the valve stem .....can't repair and could not find a reasonable price so bought 3 complete seal kits with valve stems from USA for same money as one bought here if they had one in stock.......so repaired my gun and sold two kits on auction site £15 each.......they were £28 here if you could get them

  6. #6
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    Just had to seal a Crosman Backpacker. Was no problem except for the pump cup. Could only source them from one supplier in UK but they want a lot for postage, more than the cup price. I managed to get one from a member on here, and now have the new dimensions, decided to try to make the next one I need from polyurethane.

    Baz
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  7. #7
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    Quote Originally Posted by Benelli B76 View Post
    Just had to seal a Crosman Backpacker. Was no problem except for the pump cup. Could only source them from one supplier in UK but they want a lot for postage, more than the cup price. I managed to get one from a member on here, and now have the new dimensions, decided to try to make the next one I need from polyurethane.

    Baz



    I just machine the tit off the front of the valve and then use an O ringed flat top piston, Baz.

    It's 20p a seal change after that.



    All the best Mick

  8. #8
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    I can supply seals for a lot of the crosman range inc ftp's and converting the valve front to a ft
    I get my pump cups stems and checks from a UK supplier but the cups from the US are often the later type that fit the front of a valve better (p1377 model)
    on a 13xx there is only 3 orings a tp seal check seal valve stem and pump cup
    probe (varies on model)
    valve inner same for all
    valve outer same for all

  9. #9
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    Rats, looked on here a short while ago, Baz was the last poster then, made a cuppa & placed an order, just about to thank all for their advice & saw ped had been kind enough to reply, sorry ped I'd have contacted you first if I'd seen your post before. But thanks, will keep a note for the future though.

  10. #10
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    Mick, do you get a good pressure with the O ring ? Sounds like a good idea to simplify the whole thing.

    Baz
    BE AN INDEPENDENT THINKER, DON'T FOLLOW THE CROWD

  11. #11
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    Quote Originally Posted by Benelli B76 View Post
    Mick, do you get a good pressure with the O ring ? Sounds like a good idea to simplify the whole thing.

    Baz
    Hi Baz,

    Yes, they make extremely good pressure using an O ring as there's less lost volume in the system.

    The only drawback is that in opening the pump for the first stroke you're drawing a vacuum until the O ring reaches the cocking lever slot, whereas the original lip seal allowed air past on opening the pump.

    This is no big deal as both my multi pump Titan Mowhawk and Daystate Sportsman are the same as both use an O ring for a piston head seal.

    BTW the single stroke Mohawk doesn't need to create a vacuum as it can draw air in through the barrel past the exhaust valve if you leave the hammer forward.



    All the best Mick

  12. #12
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    Very interesting, thanks. I have an old Crosman that gingernut on here gave me that needs an obsolete pump seal. Yet another project coming on.

    Baz
    BE AN INDEPENDENT THINKER, DON'T FOLLOW THE CROWD

  13. #13
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    it's possible to eliminate the vacuum effect by fitting a one way valve in the piston but this would then create head space which could be then resolved but I've never had the need to do this

  14. #14
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    Quote Originally Posted by T 20 View Post
    I just machine the tit off the front of the valve and then use an O ringed flat top piston, Baz.

    It's 20p a seal change after that.



    All the best Mick
    And many would pay (about £40?) for the flat top conversion? Think it includes the replacement valve, piston head and 'O' ring. Awesome for those who can do the work themselves.

    Seem to remember efficiency is greatly improved due to the extra swept volume; 7 pumps giving the same power as 10 on the standard set-up?

    By the way, off tangent a little........The 1377 I bought last year seems much lower power than my other one from 2009. I'll have to chrono to check. I believe there's a "pressure bleed hole" somewhere on said valve. Anyone got any tips for the best way of blocking this for when I come to play with it one day?
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  15. #15
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    the UK/Can 1377 valves have the blow by hole and easily cured by threading the hole m3 and thread locking a m3 grubscrew in,some I found also had the bottom of the exhaust chamber (below port)bored to increase volumeof that area so the pressure at the pellet was reduced

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