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Old 10-09-2012, 05:39 PM   #1
osro OP
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Cry '77 R75/7 no longer shifting from 4th to 3rd!

Help! I've got a '77 R75/7, I've had it for about two months and while its my first BMW airhead I've had a Dnepr for 2.5 years.

As of this morning it no longer will shift from 4th to 3rd. When I try to downshift the bike goes into a false neutral, and when I down shift again there is a loud CLUNK and the bike is then in 2nd gear. I ride just about every day and this has been happening inconsistently for about 2 weeks, but as of this morning it is 100% consistent and I can't get a clear shift from 4th to 3rd at all. If I downshift from 4th and then upshift it goes into 3rd, but obviously thats not what we're looking for.

This afternoon I adjusted the clutch and its still happening! Does anyone have any advice? (Other than crack open the whiskey )
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Old 10-09-2012, 06:31 PM   #2
disston
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The transmission is in need of repair. How many miles on this transmission? This bike? Irregardless the trans will need a complete rebuild, 5 bearings a couple small parts, gaskets and seals. Can run from $500 to $1000. Can you do the trans removal and replacement?

Or are you the one to rebuild your own? You'll need several hundred dollars in special tools and also be advised that the Airhead trans is not considered a DIY trans unless you have extensive mechanic experience.

While trans is out the clutch will need to be checked and the engine rear seal checked because they are accessible with transmission removed it just makes sense to do this at this time.

You have a lot of reading to do the next couple of days. Here's a good one to start;

http://www.largiader.com/tech/airtrans/
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Old 10-09-2012, 06:37 PM   #3
osro OP
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The bike and transmission have about 100k on them (I believe).

I'm no stranger to pulling a transmission, but I'd rather have a professional do it. Any recommendations on good ones in Houston?
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Old 10-09-2012, 07:26 PM   #4
disston
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Your reply has maybe two meanings. Did you mean to say you will pull the trans but need somebody to rebuild it. Or you said you want somebody who does the whole enchilada?

There may be somebody in or close to Houston. Hopefully somebody will post an answer.

If you are going to pull the trans there are several people that you can send it too for repair. The person responsible for the Web Site I gave you earlier, Anton Largiader, does mail order transmission repairs. He is considered one of the Pros at Airhead transmission repair. In fact Anton is one of the Gurus.
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Old 10-09-2012, 08:05 PM   #5
bmwrench
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It upshifts normally to 3rd? Any new noises?
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Old 10-09-2012, 08:27 PM   #6
Wirespokes
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It's true, something may be wrong inside the box, but let's rule out simpler and cheaper things first!

Often, difficulty down shifting is a result of dry transmission input splines. I have no reasonable explanation why only into 3rd, but there's that.

My next idea is something wrong with either the shift mechanism, or the shaft the gear slides on.

One of the first diagnostic steps with transmission problems is checking the drain magnet for any particles larger than soft fuzz. And how much silver and coppery sparkles in the oil?
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Old 10-09-2012, 08:36 PM   #7
osro OP
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I owe all of you an apology, I just went on a 20 mile ride and made a concerted conscious effort to firmly and deliberately shift (up and down) and did not once hit a false neutral on any gear shifts. I'm not sure what in hell I was doing on my drive to work, my drive from work, and my shake down drive after adjusting my clutch, but at least right now it looks like human error. My guess is after the first couple of bad shifts I started started over-thinking and ended up shifting like a jackass..

Thank you all for your help, if you're ever in Houston, beers are on me!
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Old 10-09-2012, 08:54 PM   #8
Wirespokes
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Glad it was a 'no situation'!

You've gotten your first lesson about these bikes - they have to be ridden 'their way'. You can't just shift how YOU think it should work; it takes special knowledge and understanding to work it properly as IT wants to be controlled.

Don't fight it! Once you learn all the 'right ways' unimaginable pleasures will be yours.
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