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Thread: Fork Slider Oil Leak

  1. #1
    Registered User rapz's Avatar
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    Fork Slider Oil Leak

    I'm converting my ATE brakes on my '79 R100RT with Brembo brakes. I've switched out the sliders, but one of them leaks oil. I don't know what year bike those sliders come from and the only number I find on them is No. 1241643. I had to switch out the bolt on bottom of the slider as the ones on the ATE are different that the sliders with the Brembo brakes. The bottom bolt for the newer sliders have a shoulder on them and actually fit into the slider. Does this bolt need a washer? These newer sliders also have a drain plug and a ring on the bottom of the slider (see picture). I don't think the oil is leaking from the bottom bolt or from the drain plug. Is there some sort of seal that may need replacing if I take the big ring off? Appreciate any help. Thanks!
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    Website: www.airheadmoto.com
    IBA No. 58411
    Current Bike 1979 BMW 100RT; 2013 BMW R1200RT 90th Anniversary Edition; 2008 Harley Davidson Ultra Classic 105th Anniversary Edition

  2. #2
    Registered User PAS's Avatar
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    If your slider looks like this then go to Max BMW webpage and look up the parts fish and find this drawing number (31_0356) R100RT 1981. It will tell you what is needed. A crush washer under the bolt heads.
    slider.png

  3. #3
    Registered User rapz's Avatar
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    It's almost exactly like that, except where's the snap ring? That's what's got me puzzled? Is there some type of seal under that snap ring that should be replaced? I can't find it in the BMW parts fiche and I've looked at other model. The part fiche you posted doesn't show that.
    Website: www.airheadmoto.com
    IBA No. 58411
    Current Bike 1979 BMW 100RT; 2013 BMW R1200RT 90th Anniversary Edition; 2008 Harley Davidson Ultra Classic 105th Anniversary Edition

  4. #4
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    Without a crush washer acting as a seal for the cap screws, oil will leak. After putting in crush washers, removing the circlip and cleaning should provide a better indication where the leak is from. If there is strong evidence that the leak is from the plug with circlip, then the lower will need to removed and penetrating loctite used to seal the plug. Good luck!
    Stan

    AH# 13238

  5. #5
    Registered User PAS's Avatar
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    You could remove the clip and disk, solvent clean it and apply rtv or other sealer then put it together. With new crush washers. Have no idea why the two parts are not shown.

  6. #6
    Bluenoser
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    There is no seal under the snap ring. Removing it allows you to take the fork completely apart. Other than the fork seal at the top of the bottom portion of the fork and the bolt at the bottom ( where the ball bearing and spring are ) there is nothing else that keeps oil in the fork. On the rebuild kit I'm looking at there is a small copper crush washer that fits over the nut at the bottom of the fork, but in reality a rubber oil ring would work fine.

    It's been my experience that most of these bolts that attach the axle to the forks have had a flat washer of some type between the bolt and the flange. The fork lowers are just a cast aluminium piece, so they are soft. The washer protects when you are torqueing the bolt.

    If you go to Bob's or one of the other BMW sites and look at the parts fiche for the year of forks you are putting on, you should be able to get a better view of the different parts of the front fork.
    1971 R50/5 SWB with R75/6 drivetrain
    2013 DL650

  7. #7
    Registered User PAS's Avatar
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    I made an enquiry in the airheads from and found that there IS an o-ring of sorts that fits under the disk on the inside of the fork. It is not available and I believe it is triangular in a crosscut view.

  8. #8
    #4869 DennisDarrow's Avatar
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    Have you tried talking with:
    Bench Mark Works.......benchmarkworks.com?

    I rebuilt the forks on my /6 with the patient advice and parts from them. Good guys and they specialize in the unobtainium that sometimes is reported as not available. I remember the large copper "O" ring as well as the smaller copper crush washer that I used in the cleaning and reassembly process.........Good luck and God bless......Dennis

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