Final drive + water = milky gear oil

Discussion in 'Old's Cool' started by Airhead Wrangler, Sep 22, 2009.

  1. Airhead Wrangler

    Airhead Wrangler Long timer Supporter

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    Sooooo,
    after a long rainy ride a few weeks ago I thought I'd check my final drive oil as my breather has managed to let water in before. Sure enough it was milky and gross. I drained it but am now left wondering: most people say they only change their final drive / tranny / driveshaft oil every 10,000 miles yet mine gets water in it any time I cross a stream or ride in the rain for hours on end. Do most just accept this and allow it to cook out the next time you ride or what? I don't feel like changing all my gear oil weekly. Anybody care to just tell me it's OK?
    #1
  2. 240sx4u

    240sx4u Been here awhile

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    Water is bad news. Maybe time to reevaluate the way the breather is setup.
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  3. mykill

    mykill odd

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    Water is bad, but a wise older BMW mechanic reminded me that these things heat up and cool down. The heating gets rid of water and the cooling attracts it. Change as specified, but make sure your breather is not a funnel.
    #3
  4. StephenB

    StephenB G(/)S ... what else!

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    It isn't ok, you need a suitable breather design:

    Gimmick2: remote final drive vent (final drive vent beveldrive reardreive)


    I never liked the oilmist around the filler plug and the inspection plug of my rear drive. As we all know, the filler plug works as a vent as well and I never knew whether after heavy rain I got water in there or not without draining the oil. I already had the inspection plug weld shut when Bruno worked on my rear drive, and I had my local machinist have a looksee at the filler plug. We bounced off a couple of ideas how to best get a M10x1 thread in there in order to use a stock banjo bolt used on the brake master cylinder (a modification that I had seen somewhere else before). Well, the modification did not go as well as we thought, so Richard just fabricated a new plug, a stainless female-female adapter M18x1.5 / M10x1.0:

    <center>
    [​IMG][​IMG]
    Click pictures for higher resolution ...
    </center>
    Now, that worked out nicely and made a professional vent that leads under the seat. So no more oil mist outside or water in the final drive anymore:


    <center>
    [​IMG][​IMG]

    Click pictures for higher resolution ...
    </center>
    Hope that helps someone else as well.
    #4
  5. Airhead Wrangler

    Airhead Wrangler Long timer Supporter

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    Stephen, I've seen your breather setup before and that's exactly what I aim to do, but just haven't found the time to go through this with a machinist and was convinced that there was an off-the-shelf part that would do the same job. I searched high and low and found nothing and eventually gave up on the whole breather thing until my rainy ride convinced me that I need to do something about it NOW. After another hour of searching I found this (exactly what you have for $10):

    http://www.touratech-usa.com/shop/show.lasso?SKU=015-0053

    I'm gonna go pick one up on my lunch break as the touratech shop is just down the street from my office. Ha! Done.
    #5
  6. StephenB

    StephenB G(/)S ... what else!

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    Problem solved.
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  7. icebox

    icebox Long timer

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    Heavy equipment uses vents with some fairly small metric threads. No need of a hose, usually a ballcheck and seat, very small on the older style. Newer vents are actually using breathable membranes. Will see what I can dig up. I have a bunch of them for different styles of Pisten Bully gearboxes, transfer cases etc. They are small enough to screw right into threaded fitting just like a temp sender. Never have liked hose style vents, on any differential
    #7
  8. StephenB

    StephenB G(/)S ... what else!

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    That would be fairly unhealthy condition for my wallet, risk of severe emptiness and constant low tide!
    #8
  9. Airhead Wrangler

    Airhead Wrangler Long timer Supporter

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    Correct. I was shocked when this fitting only cost $9. I didn't think they'd sell me a nut for less than $50. Their stuff (for the most part) is well made and always fits correctly, but it certainly is overpriced. Yikes. At least they still make stuff for airheads though.
    #9
  10. bgoodsoil

    bgoodsoil Dare to be Stupid

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    I'm looking forward to this one! If it works out I may owe you a beer.
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  11. Andy-Gadget

    Andy-Gadget Any bike can go anywere

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    On the older final drives the breather is a press fit in the housing, a bit of machining and this to is fixed.

    This is the final drive off my RS, that is being fixed after 375k, and after a few milky final drive (and gearbox) incidents, this was the fix I came up with.
    [​IMG]

    The fuel hose goes forward to the gearbox breather, where I replaced the original breather bolt with a banjo bolt type arrangement so the gearbox didn't ingest its share of a deep water crossing either.
    The gearbox still needs the speedo cable boot full of grease fix or the water can still get in there.
    The now joined hoses then went up to just behind the steering head, with foam zip tied over the end.
    #11
  12. Airhead Wrangler

    Airhead Wrangler Long timer Supporter

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    Now you're talkin. River crossings on sport-tour bikes. Yes.
    #12
  13. bgoodsoil

    bgoodsoil Dare to be Stupid

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    that's nothin. I once saw a guy on a r1200GS ride across his perfectly flat front lawn on a sunny day. It got a little hairy about halfway but he made it. that guy was nuts huh?
    #13
  14. Airhead Wrangler

    Airhead Wrangler Long timer Supporter

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    SUCCESS!!

    It works! (or at least it looks like it should)

    Parts needed:
    Touratech IMO oil drain for use with temp sensor (M18x1.5, M10x1.0)
    M10x1.0x? banjo bolt (same as used for R100GS front brake, not sure of length)
    Two crush washers
    old banjo connection off of junk brake line
    length of rubber vacuum line

    [​IMG]
    #14
  15. C Squared

    C Squared Now with TURBO! Supporter

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    Good info Guys.....

    As a recovering hard core Land Cruiser addict.....(trail not street truck)

    Similar things happen. Run the vent up high. Run it into your air box.

    Hint: when the hot case hits the cold water a vac. is created inside the case and it will pull water in through places that do not leak normally.

    Same thing happens when folks drive to the cabin and then back the boat into the water and dunk the diff in the lake.


    Cheap fix (but I like the ones shown) Drill a hole in the center of the stock plug and tap it to accept a barbed brass hose fitting. Available in many sizes and angles. A small hose is plenty of breather.
    #15
  16. bikecat

    bikecat Long timer

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    The paralever's vent is different; just a black cap with side holes. Does that get the job done or a change is necessary?

    Cheers
    #16