The Airheads Beemer Club is a non-profit club reclaiming the 'Legendary Motorcycles of Germany'

Topic-icon S.O.S. Airhead transmission issues

  • HermanMunster
  • HermanMunster's Avatar Topic Author
  • Offline
  • R100 Level
  • R100 Level
More
3 months 2 days ago #5058 by HermanMunster
S.O.S. Airhead transmission issues was created by HermanMunster
Just joined the forum as an attempt to get some input/advice from others!

Background: purchased this 1993 R100GS last year in October. Not sure how many miles as it looks like the speedo was replaced. My wife also has a 93 R100GS. We recently got married , we're from Texas, and are on our honeymoon. For said honeymoon we shipped both GS up to Montana and are riding to Alaska.

This morning we rode from Jasper in Alberta Canada and made it to Grand prairie, and after coming to a light I heard a loud squeal coming from the transmission. I'll try and attach a video for you all to hear. But we're stranded in GP until we can figure it out.

Here's what we've noted so far:

-the bike can idle with the clutch disengaged with no noise.
-the bike can be in neutral with the clutch engaged and no noise.
- I got the bike up to maybe 25mph and shifted through all 5 gears, the noise got progressively quieter once I got to 5th gear (at a very low speed)
-my clutch cable snapped shortly after I pulled over when attempting to ride it to a guy's house that was willing to help
-i popped it in neutral with the engine off and pushed it to his house, and with the engine off in neutral, pushing the bike it made the noise just as loud.

Any ideas?? At this point we're trying to decide whether we should go into it, or just try and get it back home

Link to video:

Please Log in to join the conversation.

More
3 months 2 days ago - 3 months 2 days ago #5060 by Wobbly
Replied by Wobbly on topic S.O.S. Airhead transmission issues
Welcome Aboard !

Sorry, but first time posters have to wait for their post to be cleared. Your thread is now posted.

In the last years of production, BMW decided to leave out a circlip in the transmission. On some bikes the unprotected gear then walks off the shaft. One of the gearbox experts will be by shortly to diagnose and give options.

Don't hide 'em, Ride 'em !!
#15150
Last edit: 3 months 2 days ago by Wobbly.

Please Log in to join the conversation.

More
3 months 1 day ago #5061 by 8166
Replied by 8166 on topic S.O.S. Airhead transmission issues
When a gearbox makes any kind of noise, it's usually big trouble. But let's make sure it's really the gearbox.

Put the bike on the center stand with the engine off and rotate the rear wheel. Watch the tire rotate past the swingarm and make sure that the tire isn't rubbing on the swingarm. If it is, the tire is either too wide or there's a bearing issue in the final drive. Grab the rear wheel, one hand at 9 o'clock, the other at three, and push with one hand and pull with the other. Alternate back and forth to feel for any play. Repeat with your hands at 12 o'clock and 6. If you feel any play, watch the little gap between the rear hub and final drive to see if it changes width as you move your hands. Movement = bad final drive bearing, and time to find a good mechanic or find a good used final drive.

The later 5 speed transmission in your bike uses a cartridge style throwout bearing. That cartridge has been known to swell and make noise because it is made of plastic. You can check it by removing the clutch actuating arm at the back of the transmission, then removing the rubber bellows over the throwout bearing. You'll need some sort of hook to fish the bearing out of the transmission housing, and you may need to remove the rear wheel to make room. If the throwout bearing won't come out, you may have found the problem.

While the bike is on the center stand with the engine off, rotate the back wheel and listen for sounds that might be associated with a failing u-joint in the drive shaft. Periodic clunking, clicking, and maybe even squealing signal trouble.

Remove the hose clamp that holds the swingarm boot to the back of the transmission and push the boot back to expose the output flange of the transmission. Slowly rotate the back wheel with your finger riding on the outer edge of the output flange. You shouldn't feel any grittiness or periodic resistance to rotation. This test isn't very definitive because of all the leverage applied by the back tire, so if you don't feel anything, you're not out of the woods yet. Remove the four bolts securing the drive shaft to the output flange, push the drive shaft to the rear to create a gap between the drive shaft and output flange, and with the transmission in neutral, rotate the output flange with your fingers. If you feel anything but buttery smoothness, there is an almost 100% chance that the bearing supporting the output shaft has moved, very likely due to the missing circlip that Wobbly mentioned. If you continue to ride the bike, that bearing will fail, scattering metal throughout the transmission and greatly increasing your repair costs. Total failure while riding could even lock the rear wheel and cause a very bad accident. Do not ride the bike if you find grittiness or a tight-loose-tight feeling as the output flange is rotated; you're just asking for big problems.

It's not a side-of-the-road repair, and requires the services of a trained transmission specialist. Very few BMW dealerships are equipped with the knowledge to properly undertake the work. The closest place I'd trust is Bob's Motorwerks:
Bob's Motorwerks
This email address is being protected from spambots. You need JavaScript enabled to view it.
132 Blanchard Butte Rd.
Roberts, MT USA
phone: 1-406-445-2044

You'll find more info on the circlip here:
www.gunsmoke.com/motorcycling/r100gs/tranny_circlip/index.html

And details the drive shaft and transmission checks here:
www.gunsmoke.com/motorcycling/r100rt/transmission/index.html

Run through those checks and let us know what you find. Hopefully it's something simple and you can continue on your honeymoon. If not, consider renting a box truck and continuing on your trip, alternating between the two of you who rides the bike and who drives the truck. If nothing else, you'll have a nice, dry place to sleep if the weather doesn't cooperate. Alternately, if you've got a place to work, it isn't a huge job pulling the transmission out, and any UPS Store can help you double box it and ship it off for repair. In a week or two you could have it back better than new, and in the mean time rent a car and continue on in it. Lots of alternatives for you out there; it's why they call it adventure touring!

Good Luck!

8166 Scot Marburger, This email address is being protected from spambots. You need JavaScript enabled to view it.
Check out the Yankee Hill AirTech Weekend, April 20-21, 2019

Please Log in to join the conversation.

  • HermanMunster
  • HermanMunster's Avatar Topic Author
  • Offline
  • R100 Level
  • R100 Level
More
3 months 1 day ago #5062 by HermanMunster
Replied by HermanMunster on topic S.O.S. Airhead transmission issues
Thanks Wobbly and 8166!
We did some additional troubleshooting as suggested. There is definitely an issue with the gearbox, noises cannot be isolated to one shaft within the box so there may be multiple issues. The oil looks like a metallic paint job in the sun though no hard chunks on the magnetic drain plug or in the oil that we saw. The glitter looks like it may be bronzy...
We touched base with Bob of Bob's Motorwerks. He is available and willing to help us out with a rebuild. We met a guy willing to let us use his garage to do some trouble shooting. We pulled the tranny out this morning, rented a car and are driving the transmission down to Bob in Montana now.

Please Log in to join the conversation.

  • HermanMunster
  • HermanMunster's Avatar Topic Author
  • Offline
  • R100 Level
  • R100 Level
More
2 months 4 weeks ago #5079 by HermanMunster
Replied by HermanMunster on topic S.O.S. Airhead transmission issues
Just an update, we got to Bobs Monday morning to begin tear down. What an amazing experience working with Bob. He is passionate about what he does but more importantly he is a genuinely nice guy. We're very grateful to be able to spend the day with him and soak up all the Airhead knowledge that he was pouring out.

After tear down we were all surprised that the tranny actually didn't look that bad. None of the bearings sounded/felt horrible, and all of the gears looked to be in great shape. It was evident someone had been in it before and had some assembly errors, Like forgetting to install a cover gasket (which means it probably wasnt shimmed correctly). So we machined the output shaft for the circlip, and replaced all bearing and seals. Then we properly shimmed each shaft, and were done in time for dinner. We're heading back to Canada now to find out if this was the culprit.

Please Log in to join the conversation.

More
2 months 4 weeks ago #5080 by 8166
Replied by 8166 on topic S.O.S. Airhead transmission issues
Thanks for the update.

Sounds like you're on your way to a happy ending!

8166 Scot Marburger, This email address is being protected from spambots. You need JavaScript enabled to view it.
Check out the Yankee Hill AirTech Weekend, April 20-21, 2019

Please Log in to join the conversation.

Moderators: 8166Wobbly
Time to create page: 1.101 seconds