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Thread: Gear oil leaking from the drivehsaft boot.

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    Registered User georgej's Avatar
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    Gear oil leaking from the drivehsaft boot.

    1978 R100RS.As the title states, gear oil is leaking from the rear clamp of the driveshaft boot. The u-joint bolts are tight and nothing else is loose in there.Is it possible that I overfilled the gearbox with oil?
    Thanks,George
    1978 R100RS Motorsport
    1978 R80/7
    1977 Triumph Bonneville
    1980 Honda XL500S

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    Administrator 20774's Avatar
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    Quote Originally Posted by georgej View Post
    1978 R100RS.As the title states, gear oil is leaking from the rear clamp of the driveshaft boot. The u-joint bolts are tight and nothing else is loose in there.Is it possible that I overfilled the gearbox with oil?
    Thanks,George
    Has anything changed in the maintenance of the bike? When did you change the driveline fluids? Check the boot clamps and also be sure the boot is seated properly...when I did a clutch job, I didn't get the boot back on the flat part of the driveshaft and had some weeping. I relocated the boot, tightened it, and no more leak.

    It's a little hard to overfill the gearbox unless put oil in it with the bike leaned over to the right. Remove the left-side fill plug and see where the oil level is...should be the bottom of the hole. Removed the fill plug for the final drive...oil should be at the bottom of the threads. There should be at most 150cc of oil in the driveshaft...you can actually put in 100 or even 50cc and still probably be fine. To know how much was in there, you'ld need to drain the shaft and measure the amount that comes out.
    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!

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    Registered User PAS's Avatar
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    You have to determine if the gear oil is coming from a bad rear seal in the gearbox, or you over filled the drive shaft or if the seal in the final drive is bad. It can migrate forward into the rubber boot if the FD seal is bad.

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    Registered User lmo1131's Avatar
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    Or the boot simply developed a pin hole and is now leaking... clean up the whole mess, give it all a blast at a car wash, dry it all off and see if you can zero in on where it's coming from. The old, tried-and-true trick is to sprinkle talcum powder on the parts to locate any leaks.

    http://www.bmwmoa.org/forum/showthre...20shaft%20boot

    If you've recently replaced the clamps you may want to read this

    http://www.bmwmoa.org/forum/showthre...ft-Band-Clamps
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  5. #5
    Registered User amiles's Avatar
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    It would behoove you to check the breathers, pressure build up with heat could do this.

    Some don't fill the rear drive reservoirs all the way to the plug to allow for expansion of the fluid.

  6. #6
    ONE LESS HARLEY 04r1150rs's Avatar
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    I assume your drive shaft housing is in an oil bath??? Do you have the old style clamp? If so when tightening it up the rubber will wrinkle under the screw allowing oil to ooze out. The newer style clamp has a metal over lap under the screw which won't wrinkle when tightened. I recently fought this issue on my G/S. You might try adding a strip of sheet metal under screw so the wrinkle won't develop. just a strip less than 1.5 inches long, maybe 3/8" wide.
    Richard
    2004 R1150RS
    1984 R80 G/S
    2003 Suzuki DRZ 400S

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    georgej- I have the same problem with my '77 r100rs. My mechanic said it was a loose clamp issue, but tightening has not resolved. Last year the bike was tilted forward for an extended period of time after i removed the rims/tires while doing maintenance, so I assumed final drive oil migrated forward, but why the leak?? Not sure how much oil should normally be inside the boot?? I would not think much. I'm leaning towrds a bad seal either at the trans or final drive, with final drive being the more likely culprit. Let me know if you get your problem resolved.

  8. #8
    Registered User georgej's Avatar
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    The screw on the clamp was at the bottom of the boot.I took the clamp off and put it on so the screw is on the top.This way seems to tighten it up better at the bottom and it has since stopped leaking.I still wonder if I had to much oil in there. I took the fill plug off and the oil is just below the bottom of the hole.When I added the oil earlier it was running out of the hole. Now we just have to work on that noise as the real wheel turns.U-joint is tight.We're going to re-allign the wheel and see what happens.
    1978 R100RS Motorsport
    1978 R80/7
    1977 Triumph Bonneville
    1980 Honda XL500S

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