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Thread: Fork leak from not riding?

  1. #1
    Registered User DonTom's Avatar
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    Fork leak from not riding?

    I have been busy with other things and my 1971 BMW R75/5 has been on the center stand in the garage for more than six months without being moved. It gets very hot in there during the summer, perhaps 110F plus.

    I recently noticed a big puddle of fork oil under the left fork, on the bottom of the front tire, tire rim as well as on the ground. A lot. Perhaps all of it leaked out, but only from the left fork.

    I rebuilt the forks around three years ago, new seals then.

    I never had a fork leak while I was riding the bike last summer, after the bike sat.

    So what could now be happening here?

    -Don- Reno, NV
    Last edited by DonTom; 08-22-2016 at 03:12 AM.
    Original owner of:
    1971 BMW R75/5, 1984 Yamaha Venture, 2002 Suzuki DR200SE, 2013 Triumph Trophy SE, 2016 Kawasaki Versys 650 LT, 2016 Moto Guzzi Stelvio, Zero DS ZF 6.5.

  2. #2
    Registered User Anyname's Avatar
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    Make sure it's oil. I had that happen to me and it turned out to be dog related, not oil...
    BMW R bike rider, horizontally opposed to everything...

  3. #3
    Registered User DonTom's Avatar
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    Quote Originally Posted by Anyname View Post
    Make sure it's oil. I had that happen to me


    and it turned out to be dog related, not oil...
    Well, I am sure it is fork oil. No dogs near there at my other house. But I have not taken a good look at it yet. For all I know, the nut could be loose and that would perhaps explain it.

    The next time I am there, I will take a better look and replace the fork oil. I will drain each fork into a measuring cup and see how much is in each.

    I expect to be riding a lot in another week, but I have five motorcycles to ride.

    -Don- Reno, NV
    Original owner of:
    1971 BMW R75/5, 1984 Yamaha Venture, 2002 Suzuki DR200SE, 2013 Triumph Trophy SE, 2016 Kawasaki Versys 650 LT, 2016 Moto Guzzi Stelvio, Zero DS ZF 6.5.

  4. #4
    Could it be brake fluid dripping down?

    What possible "dog related" issue could this be? Hmmmmmmm?
    "The difference between death and taxes is that death doesn't change every time congress meets." - Will Rogers

  5. #5
    Registered User lmo1131's Avatar
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    Could it be brake fluid dripping down?
    Prolly not, cable operated drum brakes....
    "It is what you discover, after you know it all, that counts." _ John Wooden
    Lew Morris
    1973 R75/5 - original owner
    1963 Dnepr

  6. #6
    Registered User DonTom's Avatar
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    Quote Originally Posted by SCBuckeye View Post
    Could it be brake fluid dripping down?

    What possible "dog related" issue could this be? Hmmmmmmm?
    What is brake fluid? This is a 1971 TRUE classic (that means NO disk brakes & came with a kick starter!).

    Anyway, I will probably take a closer look at the bike by the end of the week. It's located at my other home 15 miles away.

    Perhaps I will start with a fork oil change and see how much really leaked out.

    -Don- Reno, NV
    Original owner of:
    1971 BMW R75/5, 1984 Yamaha Venture, 2002 Suzuki DR200SE, 2013 Triumph Trophy SE, 2016 Kawasaki Versys 650 LT, 2016 Moto Guzzi Stelvio, Zero DS ZF 6.5.

  7. #7
    Liaison 20774's Avatar
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    Lift up the lower part of the fork gaiters and see if there's any trapped fluid in there.
    Kurt -- Forum Liaison ---> 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!

  8. #8
    If it's a big puddle, it's unlikely a seal -- the oil level shouldn't be high enough to leak from there when it sits. That leaves a leak from the bottom of the fork leg -- the washer on the drain bolt or the cap on the bottom of the fork. Both seem unlikely but after 45 years not impossible.
    '61 Clubman's Gold Star, '13 690 Duke, '13 Daytona 675R, '14 Street Triple R (gone but not forgotten: '76 R75/6, '84 R100, '76 R90S)

  9. #9
    Registered User PAS's Avatar
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    Do you still have the steering damper? Mine leaked and I thought it was the oil cooler leaking.

  10. #10
    Registered User lmo1131's Avatar
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    Do you still have the steering damper? Mine leaked and I thought it was the oil cooler leaking.
    On a '71 SWB /5, if stock, it looks like this; friction disc only, no hydraulics involved.



    "It is what you discover, after you know it all, that counts." _ John Wooden
    Lew Morris
    1973 R75/5 - original owner
    1963 Dnepr

  11. #11
    Registered User DonTom's Avatar
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    Quote Originally Posted by ccolwell View Post
    If it's a big puddle, it's unlikely a seal -- the oil level shouldn't be high enough to leak from there when it sits. That leaves a leak from the bottom of the fork leg -- the washer on the drain bolt or the cap on the bottom of the fork. Both seem unlikely but after 45 years not impossible.
    I will be looking at it more closely in a few days. Perhaps just the nut on the bottom of the fork worked loose or something simple like that. The bike is just 15 miles from here, but I have a lot of other things to deal with for the next few days.

    -Don- Reno, NV
    Original owner of:
    1971 BMW R75/5, 1984 Yamaha Venture, 2002 Suzuki DR200SE, 2013 Triumph Trophy SE, 2016 Kawasaki Versys 650 LT, 2016 Moto Guzzi Stelvio, Zero DS ZF 6.5.

  12. #12
    Registered User ebeeby's Avatar
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    May just need to torque that nut on the end of the fork (not the big nut, the little one under the rubber cap)
    1973 R75/5

  13. #13
    Registered User DonTom's Avatar
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    Quote Originally Posted by ebeeby View Post
    May just need to torque that nut on the end of the fork (not the big nut, the little one under the rubber cap)
    I think that was it! That 13 mm nut was loose, not real loose, but looser than the side that didn't leak.

    BTW, my rubber caps are missing on both sides.

    What type of fork oil do most use in a 1971 BMW R75/5?

    I will probably do that in the next few days.

    I have been so busy with so much stuff lately, but I really would like to start riding that old BMW again soon.

    -Don- Reno, NV
    Original owner of:
    1971 BMW R75/5, 1984 Yamaha Venture, 2002 Suzuki DR200SE, 2013 Triumph Trophy SE, 2016 Kawasaki Versys 650 LT, 2016 Moto Guzzi Stelvio, Zero DS ZF 6.5.

  14. #14
    Liaison 20774's Avatar
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    Quote Originally Posted by DonTom View Post
    What type of fork oil do most use in a 1971 BMW R75/5?
    I've always preferred 7.5wt BMW oil; unfortunately they don't supply that anymore. Here's a thread of mine where I've settled on 7wt Belray...haven't made the change yet!

    http://forums.bmwmoa.org/showthread....il-Part-Number
    Kurt -- Forum Liaison ---> 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!

  15. #15
    Registered User DonTom's Avatar
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    Quote Originally Posted by 20774 View Post
    I've always preferred 7.5wt BMW oil; unfortunately they don't supply that anymore. Here's a thread of mine where I've settled on 7wt Belray...haven't made the change yet!

    http://forums.bmwmoa.org/showthread....il-Part-Number
    Thanks, I just ordered a couple of quarts of the stuff.

    BTW, yesterday, I took a much closer look. I drained the forks, but only the right fork had any fork oil in it, and it had the normal amount. The left fork was totally dry. ALL of it has already leaked out. Hopefully, that slightly loose nut was the only problem. But the bike is now ready for me to add the fork oil and go for a ride and see what happens.

    -Don- Reno, NV
    Original owner of:
    1971 BMW R75/5, 1984 Yamaha Venture, 2002 Suzuki DR200SE, 2013 Triumph Trophy SE, 2016 Kawasaki Versys 650 LT, 2016 Moto Guzzi Stelvio, Zero DS ZF 6.5.

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