airhead transmission failed

Discussion in 'Airheads' started by Cavetroll, Nov 22, 2010.

  1. Cavetroll

    Cavetroll n00b

    Joined:
    Jul 1, 2008
    Oddometer:
    6
    Hi all,

    Sorry for the new thread, but I'm on limited internet time and haven't found all I need through search.

    The short version: i'm on a road trip from Addis Ababa , Ethiopia to Cape Town, South Africa on my 1991 R100GS. She developed a transmission rattle in souther Tanzania, and now I'm in Lusaka, Zambia to troubleshoot and hopefully repair.



    The symptoms:
    - 'thunk' when rolling onto or off of the throttle, or letting out the clutch
    - an intermittent vibration... appearing for half a second every 2 seconds while riding in third or fourth gear at ~3500rpm. I'm pretty sure I've seen this described as a "growl" which means my transmission shaft bearings are shot.
    - latest to develop (whlie I was riding across the border into Zambia to find a truck) is a scraping sound... as if the U-joints are rubbing on the inside of the swingarm.

    Am I crazy to try and fix this in Lusaka, with no BMW motorcycle workshop in sight? I think I can get the bearings off the shelf (non-BMW), and will have to improvise some tools (flange puller). My backup plan is to put the bike on a train to South Africa, but I want to make sure I can't fix it here before I go that way. What else do I need to look out for when opening the transmission? I'm not going to deal with the circlip for the moment... I just want to get the bie running again so I can ride it to South Africa rather than shipping it (the plan was to sell it there anyway).

    Any thoughts would be greatly appreciated!

    Cheers,
    Mark
    1991 R100GS - 80,000km
    #1
  2. bmwblake

    bmwblake upside down parker

    Joined:
    Mar 3, 2004
    Oddometer:
    3,274
    Location:
    nashville, tn
    make sure it's a transmission issue.
    drain the transmission oil and inspect.
    pull the driveshaft and make sure it's in proper working order.

    there are a couple of guys on this board in south africa. you might try the regionals forum and see if you can get some pointers from someone in the region. good luck.
    #2
  3. Foot dragger

    Foot dragger singletracker

    Joined:
    Dec 27, 2006
    Oddometer:
    13,837
    Location:
    chico,just below rag dump(nor-cal)
    Ive heard if it isnt done right it can go south again pretty quick.
    Best make sure what the problem is and then proceed accordingly,the output shaft bearing sounds suspect if theres scraping noises towards the driveshaft.
    Riding it and grinding the cases to bits or blowing a gear up will put the finis on it.
    #3
  4. chiefrider

    chiefrider Chrome won't get you home

    Joined:
    Nov 8, 2004
    Oddometer:
    2,413
    Location:
    The lovely Willamette Valley
    ditto

    Put the bike on the centerstand and get the rear wheel off the ground and tranny in neutral. You'll either have to prop the rear up with a stick, have someone lift on the luggage rack carefully so it doesn't rock off the stand, or best yet, remove the luggage and panniers alltogether. Rotate the wheel by hand. Feel notchy? It there a clunk? When all is good, the you should be able to smoothly turn it forward and backwards. Grasp the rubber boot between the transmission and swingarm. You should be able to feel the transmission output flange where it attaches to the driveshaft. Rotate the wheel a little again while grasping. You might be able to distinguish where the scraping sound is coming from.

    If it's the driveshaft, it's relatively easy to swap it out, as compared to rebuilding the tranny.

    Also, check the transmission oil--if the plug has a magnet, it should have an oily spooge the texture of toothpaste. You should not be able to feel any particles. If there are feelable particles or visible flakes of metal, the transmission's sick--likely the output shaft bearing.

    Tom in Salem
    #4
  5. Cavetroll

    Cavetroll n00b

    Joined:
    Jul 1, 2008
    Oddometer:
    6
    Thanks all for the responses. Pulled it apart today, and the upper u-joint (closer to the transmission) has completely failed. Turning the transmission output flange by hand reveals a slight notchiness, indicating time for an overhaul. I'm working on finding a place in RSA or Namibia to have the work done.

    One other question... once I get it fixed, the plan is to sell the bike. Anyone have thoughts on importation issues, sales, etc.?

    Thanks again!
    Mark
    #5
  6. Airhead Wrangler

    Airhead Wrangler Long timer

    Joined:
    Mar 4, 2008
    Oddometer:
    6,833
    Location:
    Back in Seattle, FINALLY
    Talk to this guy in South Africa (he goes by Dustdevil on here, but doesn't sign on too often):

    Altus Pienaar
    Address:
    92 Coetzee Street
    Middelburg
    Eastern Cape
    South Africa
    5900
    E-mail: altus@redskyadventures.co.za
    Mobile Phone Number: 0727688003
    http://www.redskyadventures.co.za

    He specializes in airhead GSs and can definitely get you rolling again.
    #6
  7. espressodrinker

    espressodrinker Cape Town Wanderer

    Joined:
    Mar 31, 2008
    Oddometer:
    208