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Quick $2k O-ring Question

brittrunyon

'92 R100GS
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? :ear
 
Damn. Now I forgot how it goes.
If I remember right, the black rubber end of the filter goes in first.
But what about the black rubber gasket that came with the filter?
Boy I feel stupid. :scratch

<a href="http://s1089.photobucket.com/user/brittrunyon/media/1981%20R100%20t/B0000085_zpsf24f1a7d.jpg.html" target="_blank"><img src="http://i1089.photobucket.com/albums/i358/brittrunyon/1981%20R100%20t/B0000085_zpsf24f1a7d.jpg" border="0" alt=" photo B0000085_zpsf24f1a7d.jpg"/></a>
 
Hold the presses!

I just discovered I have the wrong filter.
The right filter has rubber on both ends and is smaller than the one in my hand.
Looks like the correct filter can go either way.:D

But still, what about the medium sized black washer/gasket?
 
The black rubber rings are always already on both ends of my filter when I take it out of the box.
 
The black rubber rings are always already on both ends of my filter when I take it out of the box.

Yes, I was speaking a larger one, maybe 1 & 1/4 diameter.
I don't see how it gets used.
& from the fiche it doesn't.
Maybe this is a case where I answered my own question.
Don't you hate that!
Thanks for the replies.
 
Just anoher thought

Years ago, on my R90/6 I had a single filter, unhinged.

I was recently sold the BMW filter "Kit" which I was told the only "kit" that BMW offered. It came with a hinged filter. I think the single full length filter is still available but just not in the "kit." Personally, I prefer the full length filter and that will be what I purchase in the future as there is room to install it just over the exhaust pipe.

Also. Technically the color of an "O" ring isn't the guarantee it is one type or another. The various types of materials (and durometers) in theory could be any of the colors. Having been a buyer for a company that had upward of 80 large plastic injection presses that used hydraulic oil, I have seen the same o-rings offered by different sources but having different colors.

Generally, the white ones were teflon, but there were buna's and vitons, and others available. I once heard a person swear that the green ones were better than the black ones. That could have been, but the color per se did not dictate or guarantee that, but the material and its durometer rating.

All of that to say this, there are other sources for those o-rings and much less expensive - you just have to know the factory specs and find the same exact o-ring somewhere else.

Just a thought.
 
If you mean part number 5 in the drawing above I've never seen one in any other colour but white. It is a very pliable O Ring and feels like silicone to my fingers.
 
Remember that the pictures are somewhat generic. Tom Cutter is constantly saying that one shouldn't try to assemble a bike using the fiche pictures. Kits come with multiple parts to cover multiple situations...you don't always need everything from the kit depending on your situation. In this case, Item 5 is the -098 white o-ring and Item 6 is the shim (or washer as it's listed in the fiche table). For the '81 R100, you need all in the above picture, with the possible exception of the gasket. You said your canister depth is 3.1mm, therefore you don't need the gasket.

As for folding or non-folding filters, it is my understanding that the filter area available for either type is much more than the bike needs for nominal usage and oil change intervals. There have been instances of collapsing filters and the longer unsupported length of the non-folding filter might be susceptible to collapse. The folding filter, with the two metal rings at the fold, actually provide more strength to help prevent collapsing. I haven't seen a non-folding filter in years, although I understand they are available. I began using the folding kind, have had no problems, and really don't care to go back to the non-folding kind. YMMV...
 
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? :ear

Can you describe how you read my article and came away with that idea? The thought process? I clearly need to change something.

And Darryl, what exactly are you affirming for him?
 
It's not the conclusion I would have reached. How exactly did you reach it?

Well let's see if I can go from brain to print......?

The canister depth is 3.1mm and not rounded, therefore a shin is needed.
..............shim thickness is 0.3mm

White O-ring is 4mm

White O-ring + one shim = 4.3mm minus the canister depth of 3.1 = 1.2mm

1.2mm is approximately 25% of 4.3mm ( I think actually 27.9%)

You have me questioning my own logic, after all you wrote the book.

(edit: changed 4.4mm to 4.3mm)
 
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Looks like to me you're basically right, except that you list the o-ring thickness at 4mm but use 4.4mm in your final calculations. Therefore, using 4mm (which is what Anton has on his site), your final compression is 30%. I think that's still OK, but getting a bit high. If you were to use a gasket (0.5mm thick) the compression drops to 17.5%. That's probably acceptable. My canister depth is 2.8mm, so I definitely need the gasket.
 
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? :ear[/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.
 
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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.
 
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??
 
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" :laugh
 
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.

And I only thought I had a "Quick $2k O-ring Question" :laugh

Yup. :)
 
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