Gear shift leaking oil

Discussion in 'Airheads' started by Byron1, Oct 12, 2012.

  1. Byron1

    Byron1 Been here awhile

    Joined:
    Jul 27, 2012
    Oddometer:
    108
    Location:
    Lincolnshire, England
    Hi everyone,

    My bike has started leaking transmission oil from the gearshift mechanism. Seems like a seal has gone inside and it is trickling down the selector lever. It has only just started doing this within the last 1k miles. The bike has about 80k miles on the clock, as far as I know the transmission has never been overhauled.

    I am currently on the road and have no wish to even think about taking the tranny apart to replace the seal, or sending it off for this to be done.. I will put up with the leak for now and just keep an eye on the oil level. When I get home will have a look in more detail.

    My question is.. Has this happened to anyone before? Is it a signal of worse things to come, or is it just simply a seal that has worn out?

    Please tell me it is! :cry

    Sorry... Bike is a '79 R100RS (my first airhead :D )
    #1
  2. supershaft

    supershaft because I can

    Joined:
    Sep 9, 2010
    Oddometer:
    9,116
    Location:
    San Francisco Bay area
    It's real common. The seal can be replaced with the tranny in the bike. A lot of people will advise to rebuild the tranny regardless at 80k. I took one of mine apart at 106k and it didn't need a thing.
    #2
  3. Byron1

    Byron1 Been here awhile

    Joined:
    Jul 27, 2012
    Oddometer:
    108
    Location:
    Lincolnshire, England
    Thanks Supershaft. Was hoping that would be the case.

    We still have another 15 - 20k miles minimum left on the trip. Hopefully it won't get too much worse before I get home and have chance to dig about further. Was planning on giving the bike a complete rebuild when we finish anyway. The PO looked after it to the best of my knowledge and I have always changed gear oil every 9k.. Always comes out as clean as new, so hopefully internally it is all as good as new. Encouraging to hear you had one with over 100k that was fine.

    Out of curiosity, what is the process for replacing seal with tranny in bike? Is it as simple as removing gearshift, undoing Allen bolt, prying out seal and inserting a new one?

    Any good links or recommended reading much appreciated.

    Byron
    #3
  4. disston

    disston ShadeTreeExpert

    Joined:
    Mar 22, 2011
    Oddometer:
    12,364
    Location:
    Silver Spring, Md
    Yep. It's as simple as that. Most of the time this is all it needs and if there are no more serious complaints then you don't need any more serious repairs.

    One word of caution. The recess the seal goes into is a lot deeper than it needs to be. The seal can be driven in a lot deeper than it currently is. Make a note of how deep the seal is currently and when you drive the new seal in set it at about the same depth. Not rocket science but I drove mine all the way in before I realized it. Still works tho, you just can't see it. Lube the lip of the new seal with trannie oil when you put the shift lever back on.
    #4
  5. Horsehockey

    Horsehockey A GPS? Huh?

    Joined:
    Nov 17, 2010
    Oddometer:
    370
    Location:
    Vermont
    This is an easy road repair. Obtain seal. Someone can correct this number if incorrect for your bike, but I think it's 23-12-1-338-740.
    Find a tree. Prop bike on right side against tree. Remove shifter lever. Remove old seal with screwdriver. Careful not to mar the bore. Press in new seal, just below flush on the casting. Replace lever. You won't lose much gear oil but you can top that off later.
    #5
  6. Byron1

    Byron1 Been here awhile

    Joined:
    Jul 27, 2012
    Oddometer:
    108
    Location:
    Lincolnshire, England
    Thanks Diston,

    Good to know. Will pick one up and fit it in.

    Byron
    #6
  7. mark1305

    mark1305 Old Enough To Know Better

    Joined:
    Feb 7, 2005
    Oddometer:
    6,317
    Location:
    Merritt Island, FL
    Yep, can be done on the bike, but rather than pry the seal out with a blade, you may want to get a couple (as in just two) small self tapping screws about #4 or #6 and screw them into the seal then pull it out with pliers or vice grips on the screws.

    One method works for some folks, and the other works for some folks.
    #7
  8. batoutoflahonda

    batoutoflahonda Long timer

    Joined:
    Aug 8, 2007
    Oddometer:
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    Location:
    Easton Wa
    Mine was leaking but the seal hadn't migrated, but the cause was the nut holding the shift lever came loose. Could check that. Don't reef on it, just make sure it's snug.
    #8
  9. Padmei

    Padmei enamoured

    Joined:
    Mar 12, 2008
    Oddometer:
    4,099
    Location:
    Nelson New Zealand
    Mine was leaking & got progressively worse quickly. I noticed on the ride the gear change was very loose. I tightened it up & the leak stopped. i'm not sure of whether it needs replacing. It may be that.
    #9
  10. REALGRAVEROBBER

    REALGRAVEROBBER LEAVING GRAVES EMPTY

    Joined:
    Nov 1, 2008
    Oddometer:
    452
    Location:
    Billings, Montana
    Carefully peel the seal out, clean it well. Tap a new one in with a deep socket or something suitable. Tip bike against a wall or something to keep gear oil in transmission from interfering with the new seal between the case and seal. About the easiest seal to change on a bike :D Hope this helps
    #10