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Old 11-22-2010, 07:55 AM   #1
Cavetroll OP
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Joined: Jul 2008
Oddometer: 6
airhead transmission failed

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
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Old 11-22-2010, 08:05 AM   #2
bmwblake
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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.
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Old 11-22-2010, 08:10 AM   #3
Foot dragger
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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.
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Old 11-22-2010, 08:32 AM   #4
chiefrider
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Quote:
Originally Posted by bmwblake
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.
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
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Old 11-23-2010, 03:10 AM   #5
Cavetroll OP
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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
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Old 11-23-2010, 06:29 AM   #6
Airhead Wrangler
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Location: Back in Seattle, FINALLY
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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.
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Old 11-23-2010, 06:43 AM   #7
espressodrinker
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Post your problem in the S.A. Forum

http://www.wilddog.za.net/forum/index.php?action=home
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