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Thread: Oil From Clutch Boot

  1. #1

    Oil From Clutch Boot

    On my '84 R100RT, I'm getting oil mist on the outside of the clutch boot, with enough on the clutch actuating lever to have a nice collection of road gruck and a droplet forming on the end. There's no oil trail leading back to the airbox, so I don't think it's crankcase vapors. I didn't check the oil I wiped off for smell, but I'm thinking it's gear oil. I see nothing coming from the rear transmission cover gasket. Does this set of symptoms/non-symptoms mean my clutch piston's seal has seen its last days and the piston needs replacement? Clutch action remains fine.

  2. #2
    Liaison 20774's Avatar
    Join Date
    Sep 2005
    San Antonio, TX
    I think you're on the right track. You could clean things up well and go for another ride and two and reinspect to get a better handle on the source of the leak.
    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!

  3. #3
    Registered User PAS's Avatar
    Join Date
    Jun 2011
    N.E. Ohio
    Check your air cleaner housing. There is a vent at the back bottom. See if its leaking from there!

  4. #4
    Day Dreaming ... happy wanderer's Avatar
    Join Date
    Mar 2010
    Vancouver, B.C. Canada
    The rubber cup that surrounds it is sealed at the outer end and there is a circular clamp around the front of it where it slides onto the rear of the gear box. This is usually the source of leakage especially as the bike gets older. Remember that a few tear drops of gear oil on a hot aluminum surface will spread all over the place and ALL of it attracts dirt. This makes a very tiny leak or seepage look a lot worse than it really is. Over tightening of the clamp often causes a leak.
    MJM - BeeCeeBeemers Motorcycle Club Vancouver B.C.
    '81 R80G/S, '82 R100RS, '00 R1100RT

  5. #5
    So I took Kurt’s diagnostic advice and put on about 150 miles yesterday going over to the Gilmore auto museum near Kalamazoo, and back. The slow weep continues, smells like gear oil, and looks to be coming from the clutch boot (the adjacent driveshaft boot looks tight and dry; nothing from the airbox above it), so I’ll put the boot on the “replace soon” task list.

    As it happened, yesterday was the annual German-marque car show at the Gilmore. 350-ish BMWs, Mercedes, Audi’s, Porsches, Opels, etc. I don’t really understand why guys with high-lease-payment late-model cars feel compelled to show their current rides at such an event—maybe they didn’t get the memo about the Gilmore being a car museum, rather than lease resale lot. But, to me, there was a bit of poetic justice when the couple with the early-80s Trabant got an award, and the well-waxed V-12 BMW and Mercedes guys went home empty-handed.

  6. #6
    Registered User 6322's Avatar
    Join Date
    Mar 2012
    Riggins, ID
    When you change your trans oil, pay attention to the level. If it's slightly over filled, it will find a way out though probably at your vent first. Most likely your problem is as you've identified, the rubber boot.
    Gary Phillips - #6322
    Wildland Firefighter, Retired, Riggins, ID
    Heartland Moto Locos BMW Riders
    '77 R100/7 Dirt Hack, '83 R80ST, '85 K100RS w/EML, '00 R1100RS

  7. #7
    Thanks. I measured about 800ccs coming out of it the other day (a tad water-contaminated—hey, I wash this thing—so the middle-aged, leathery speedo cable boot has already been replaced), and refilled with that amount. No oil’s been seen from the vent-bolt.

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