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Thread: /5 Airhead Issues

  1. #1
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    /5 Airhead Issues

    Hey all,

    So once again still finding little joys of problems with my /5. Mechanically everything was running great until yesterday morning. As I was leaving for work I noticed that when in the friction zone I was experiencing a loud squeal type noise. I stopped for a second and tried a few more times and the sound went away. I decided I would chance it to work and ended up taking surface roads. When I got home later that evening I went to put the bike into neutral from first and noticed that the shift lever seemed to be stuck.

    I move forward a few inches and tried again (thinking maybe it just got stopped in an odd position) but still no dice. I ended up friction-zone walking it into the garage and tried once more and finally got it to go into neutral, but it did not feel quite right.

    So this morning I decided to try another quick test ride and see if I felt any problems. Low and behold I hear the same squeal noise and shifting felt very wierd. I had movement and could ride but shifting didnt feel smooth or right from neutral -> first -> second gear.



    Is my transmission going south?

    The bike has 79k on it. I am the fourth owner of the bike and at least all the history I have on it. It looks like the transmission was "inspected" by a shop back in the 90s but there isnt much documentation on exactly what went on. No data on if the splines were ever lubed/etc.

  2. #2
    Registered User lmo1131's Avatar
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    It looks like the transmission was "inspected" by a shop back in the 90s
    BMWs are high mileage, low maintenance bikes, but twenty years is probably a bit too long between service.

    Have you checked the oil level in the transmission? Should be "just" at the base of the threads in the filler hole. If you haven't done so yet, I'd completely drain the transmission and check the oil for bits of metal. Your drain plug may have a magnet on the end; if it does check for metal chips.

    Here's Snobum's primer on transmissions > http://bmwmotorcycletech.info/transmission.htm

    Synthetic or Dinosaur oil is up for grabs. I'm old school about it.


    You will also want to check your clutch adjustment. If the clutch is "dragging" it can make shifting difficult.



    To Read

    http://www.bmwmoa.org/forum/showthre...-in-Clutch-rod (this one includes Tom Cutter's explanation (which is basically what is in the video above).
    http://www.bmwmoa.org/forum/showthre...tch-Adjustment

    Or, given the apparent lack of maintenance, it could be headed south.... but don't give up just yet.
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  3. #3
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    So far I've had the carbs rebuilt, points and valves adjusted, front forks rebuilt and all oil/fluids replaced and cables (as well as recently adjusting the clutch at both the hand controls and the rear of the transmission.

    The airhead mechanic I had working on it didnt notice anything suspicious with the transmission when he did the oil but who knows. I guess it depends on just how thorough he was.

    I'm going to try to get down to his shop to have him take a look at it. Im hoping it wont be anything terrible but it felt pretty odd shifting it into neutral and even up into second and third. It felt as if the shift lever was stuck (ie didnt want to budge or shift up at all)


    Here's hoping for the best.


    I guess worst case scenario the transmission gets rebuilt and she gets a lot more miles added to her belt.

    I'd eventually like to restore her as she's in mostly great shape but the cost it would take to have someone else do it would be out of my price range for sure I am betting, and I honestly dont have the tools or currently the time (or really the proper knowledge) to attempt something on my own.

    Guess itll have to wait for another day. Hah.

  4. #4
    Bluenoser
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    Check the bearing on the back of the clutch rod, called a throw out bearing in other applications. With the bike in neutral and running, pull the clutch in and see if the noise changes.

    Seeing as you previously adjusted the clutch, I would look at this as the source of your problems, before getting carried away with the transmission.

    Good luck.
    1971 R50/5 SWB with R75/6 drivetrain
    2013 DL650

  5. #5
    James.A
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    Quote Originally Posted by cycleman2 View Post
    Check the bearing on the back of the clutch rod, called a throw out bearing in other applications. With the bike in neutral and running, pull the clutch in and see if the noise changes.

    Seeing as you previously adjusted the clutch, I would look at this as the source of your problems, before getting carried away with the transmission.

    Good luck.
    +1 on this.

    The /5 throw out bearing is more robust than the /6 and later design, but that doesn't mean that they can't go bad.

    Generally speaking, I always drill down into an issue starting with the easier stuff first.

  6. #6
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    Quote Originally Posted by James.A View Post
    +1 on this.

    The /5 throw out bearing is more robust than the /6 and later design, but that doesn't mean that they can't go bad.

    Generally speaking, I always drill down into an issue starting with the easier stuff first.

    Well according to the mechanic I've been taking my bike to the throw out bearing looks good still. He is t sure what the problem is but the cluth is releasing very late in the lever throw he said and he isn't able to get the adjustment to really make it any better. He said he was going to pull the transmission back and double check the actual clutch plate and check the
    Splines as well.

    This sounds like the cost is going up up up as we speak. Hah oh well. At least ill have peace of mind.

  7. #7
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    Oh and the transmission oil was checked. No metal flakes were found.

  8. #8
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    Well looks like clutch is completely shot. Damn. Oh well.

  9. #9
    Registered User lmo1131's Avatar
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    +.5 better the clutch, than the gearbox....
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  10. #10
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    Quote Originally Posted by lmo1131 View Post
    +.5 better the clutch, than the gearbox....

    Just wanted to give an update to everyone! Wow! New clutch is 100% different bike! Friction zone is much wider and the bike seems so much better!

    If anyone has a digital on/off clutch or short friction zone you may need a new clutch!



    Had the spring, clutch disk, and the two pressure plates replaced as well as the transmission input shaft. We're in business!

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