Page 2 of 2 FirstFirst 1 2
Results 16 to 24 of 24

Thread: Quick $2k O-ring Question

  1. #16
    Day Dreaming ... happy wanderer's Avatar
    Join Date
    Mar 2010
    Location
    Vancouver, B.C. Canada
    Posts
    1,913
    [QUOTE=brittrunyon;870873]I now have a 1981 R 100 & changing the oil for the first time.
    I read http://www.largiader.com/tech/filters/ & have come up with this.
    The canister depth is 3.1.
    It appears to be the squared, not rounded.
    So I plan on using a white o-ring with a shim to protect it & no gasket.
    This would compress the o-ring by about 25%.
    Is my logic flawed? [/QUOT

    In looking at Anton's canister chart

    http://www.largiader.com/tech/filters/canister.html

    it seems to me if your canister depth is 3.1 and you have the sharp (square) edged canister then you should be installing your filter, one shim, the white O Ring, a paper gasket and your cover. In that order.
    Last edited by Happy Wanderer; 04-19-2013 at 06:37 PM. Reason: Two posts while I typed this one.
    MJM - BeeCeeBeemers Motorcycle Club Vancouver B.C.
    '81 R80G/S, '82 R100RS, '00 R1100RT

  2. #17
    . AntonLargiader's Avatar
    Join Date
    Jul 2004
    Location
    Charlottesville, VA
    Posts
    1,360
    The shim is incompressible so you really need to compare 4.0 and 2.8, if you want to know the compression. However, I think the compression stuff is misguided (I think I explain some of this on that page) so I don't use it.
    Anton Largiader 72724
    largiader.com bmwra.org

  3. #18
    Administrator 20774's Avatar
    Join Date
    Sep 2005
    Location
    San Antonio, TX
    Posts
    12,820
    Quote Originally Posted by AntonLargiader View Post
    The shim is incompressible so you really need to compare 4.0 and 2.8, if you want to know the compression. However, I think the compression stuff is misguided (I think I explain some of this on that page) so I don't use it.
    Anton -

    You say it's misguided, but yet you came up with recommendations for shims, gaskets, etc. How did you decide on these configurations without considering how much "squeeze" there would be on the white o-ring?

    From your website, "..so it's really unnecessary to apply this level of precision. You need to compress the O-ring, but it's not rocket science." But there has to be some consideration for the numbers to ensure that you have "some" compression. Maybe using Airhead science??
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  4. #19
    '92 R100GS '81 R100/t brittrunyon's Avatar
    Join Date
    Sep 2009
    Location
    Embudo, New Mexico
    Posts
    375
    Quote Originally Posted by AntonLargiader View Post
    The shim is incompressible so you really need to compare 4.0 and 2.8, if you want to know the compression. However, I think the compression stuff is misguided (I think I explain some of this on that page) so I don't use it.
    So with those #'s the compression is 30%.........?
    If that's too much, what results?
    And I only thought I had a "Quick $2k O-ring Question"
    1992 R100 GS, 1981 R100/t, 2007 F 650 GS

    No Rules Photography at http://brittrunyon.com/
    My riding videos @ http://vimeo.com/user2721333/videos

  5. #20
    . AntonLargiader's Avatar
    Join Date
    Jul 2004
    Location
    Charlottesville, VA
    Posts
    1,360
    Quote Originally Posted by 20774 View Post
    You say it's misguided, but yet...
    The compression percentages, I personally feel are misguided because the O-ring is compressed radially before you even get to the canister depth. Traditional O-ring compression specs don't have that complication. So, I refer to millimeters of compression or just groove depth and I get those from my own experience and trusted anecdotal data. I shoot for 3.5/0.5, and I don't really want to go more than 3.2/0.8. So to answer my own question, you went wrong not only by miscalculating the compression but by bringing some compression % spec into the picture to begin with. That wasn't in the article.

    Later canisters which are not fully seated (an incredible oversight by BMW) can be pushed too far inward, and I think the O-ring compression is driving force for that.

    Quote Originally Posted by brittrunyon View Post
    And I only thought I had a "Quick $2k O-ring Question"
    Yup.
    Anton Largiader 72724
    largiader.com bmwra.org

  6. #21
    Administrator 20774's Avatar
    Join Date
    Sep 2005
    Location
    San Antonio, TX
    Posts
    12,820
    Anton -

    Yes, you do discuss a groove depth, somewhat in context with the compression of the o-ring. So, OK, we shouldn't focus on compression of the o-ring, which Oak had written about in one of his Airmail articles.

    But taking your numbers from your website, and computing the compression values per the basic equation, I get the following table. Interesting, your recommendation of groove depth matches quite well Oak's recommendation of compression values of between 10 and 25%.

    So while compression might not be the best way to think about this, it does appear that the two different scales really give the same range of recommendations for stack up of components.

    Another question...why is there a need for a chart for the rounded edge canister and one for the square edge canister? It's all about the initial canister depth...seems to me the shape of the edge really has nothing to do with what stack up of components is needed.
    Attached Images Attached Images
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  7. #22
    '92 R100GS '81 R100/t brittrunyon's Avatar
    Join Date
    Sep 2009
    Location
    Embudo, New Mexico
    Posts
    375
    WOW, now that's some math.
    I'll try and wrap my head around it & apply as best I can.
    Thanks for the comparison.
    1992 R100 GS, 1981 R100/t, 2007 F 650 GS

    No Rules Photography at http://brittrunyon.com/
    My riding videos @ http://vimeo.com/user2721333/videos

  8. #23
    . AntonLargiader's Avatar
    Join Date
    Jul 2004
    Location
    Charlottesville, VA
    Posts
    1,360
    Quote Originally Posted by 20774 View Post
    ... your recommendation of groove depth matches quite well Oak's recommendation of compression values of between 10 and 25%.
    If you actually read the page, you'll see that those are examples targeting an arbitrary 3.3mm groove depth. That's not a recommendation and I explain elsewhere why I use a larger number. The purpose of the whole page is to get you to do your own math. That's why I was more interested in knowing how the OP came up with his conclusion than I was in actually doing the work for him.

    The O-ring packs fully with about 0.5~0.6mm compression. There's no need to go much tighter. This is explained on the page.

    Another question...why is there a need for a chart for the rounded edge canister and one for the square edge canister? It's all about the initial canister depth...seems to me the shape of the edge really has nothing to do with what stack up of components is needed.
    The sharp-edge canister cannot offer a no-shim option, so the contents of those six rows are different.
    Anton Largiader 72724
    largiader.com bmwra.org

  9. #24
    '92 R100GS '81 R100/t brittrunyon's Avatar
    Join Date
    Sep 2009
    Location
    Embudo, New Mexico
    Posts
    375
    Quote Originally Posted by AntonLargiader View Post
    If you actually read the page, you'll see that those are examples targeting an arbitrary 3.3mm groove depth. That's not a recommendation and I explain elsewhere why I use a larger number. The purpose of the whole page is to get you to do your own math. That's why I was more interested in knowing how the OP came up with his conclusion than I was in actually doing the work for him.
    The O-ring packs fully with about 0.5~0.6mm compression. There's no need to go much tighter. This is explained on the page.
    The sharp-edge canister cannot offer a no-shim option, so the contents of those six rows are different.
    Thanks for doing all the work & sharing your the info on the $2k O-ring saga.
    I wasn't looking for you to do the work for me. I was wondering if my thinking was correct.
    But I guess in a way that's asking someone to do a little work.
    "The O-ring packs fully with about 0.5-0.6 mm compression" That's good to know, I must have missed that when reading your page.
    Thanks Again.
    1992 R100 GS, 1981 R100/t, 2007 F 650 GS

    No Rules Photography at http://brittrunyon.com/
    My riding videos @ http://vimeo.com/user2721333/videos

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •