Transmission Differences

Discussion in 'Airheads' started by Voltaire, Apr 5, 2013.

  1. Voltaire

    Voltaire Titanium and Ceramic Hipster

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    Probably been covered but I bought an R90/6 recently and I'd forgotten how clunky and resistant to change they are compared to the post 81 boxes.
    Is it just the flywheel being lighter or is there differences within the transmission itself.
    Although the heavy flywheel gives the 'vintage' feel I don't know if I can put up with it long term.
    Other than " it is what it is" any thoughts?
    #1
  2. motu

    motu Loose Pre Unit

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    I was told it was the rider - so I am obviously a much better rider now than I was when I had the R60/5. Is your riding getting worse then ?
    #2
  3. Voltaire

    Voltaire Titanium and Ceramic Hipster

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    Maybe I was spoilt with the R65..... what was that Joni Mitchell said.....:eek1
    #3
  4. gsd4me

    gsd4me 90% bluff

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    I've recently gone from an oilhead to an airhead and I'm lucky if I can make it through the first few gears without it sounding like I'm a novice.
    #4
  5. motu

    motu Loose Pre Unit

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    We are stardust ? Oh yeah, we got to get back to the garden. On tomorrows list.
    #5
  6. Plaka

    Plaka Brevis illi vita est

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    Time your shifts more carefully...and lighten the flywheel.

    Also check your clutch cable adjustment. Nickel thickness of free play at the bars. If the shift lever pivot is worn and the lever sloppy, fix that. If the shift lever rubber is missing, replace it.

    Past that (and running synthetic oil if you ever replace the seals) just dig the vintage feel...
    #6
  7. kadesean

    kadesean eyesuck

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    +1 on the timing. There are times when I just know my 1st to 2nd gear transition is going to be ugly, usually when leaving a light in traffic and I am behind a cage that isn't sure if it knows where the accelerator is. Prolly better for me to learn this and be patient, let the engine spin and shift a little higher in the RPM range. I find this to be the case on my '74 and on my '92.
    #7
  8. Voltaire

    Voltaire Titanium and Ceramic Hipster

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    Thanks guys, I'll have to rummage thru my Dads old box of coins to find a nickel...:D....that's the Jefferson bloke...?
    Seriously though, the bike has only 66k kms on it so its most likely me...... and yes its only really noticeable in traffic in the lower gears.

    Hey Motu, no chance of them putting up a parking lot any time soon down your way...
    #8
  9. Padmei

    Padmei enamoured

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    Hey bro I suspect my old box was pre 81 & huge difference with that & my new one.

    One tin soldier rides away
    #9
  10. Stan_R80/7

    Stan_R80/7 Beastly Gnarly

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    A few things I noticed on shifting my 1978:

    1. Preload helps considerably on upshifting.
    2. Each gear shift must be complete before upshifting (i.e. preload is only good after completely in gear for a moment).
    3. RPM's matter when downshifting. Syncromesh gears are not in the gearbox and the rider has to help synchronize the gears by keeping the RPM range where it would be for the gear selected.
    4. Expect the transmission to clunk some. It's the way they were made.

    YMMV.
    #10
  11. Voltaire

    Voltaire Titanium and Ceramic Hipster

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    I'm interested in what the differences are that contribute to the later ones being smoother, I took my latest purchase an 89 R100RT for a ride this morning and its quite a nice shifter ( by BMW standards)
    Is it a matter of upgrading the selector mechanism or changing the flywheel/clutch/input/release mech or what?
    Just wondering, I like to know how stuff works.:D
    #11
  12. disston

    disston ShadeTreeExpert

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    The up dated shift mechanism will fit the early gearbox. It won't effect the clunkiness. The shift mechanism helps to prevent the broken detent spring and helps to eliminate false neutrals. I believe that's it. It is an improvement but you can still have false neutrals and you can still have a broken detent spring.

    The majority of improvement in the feel and ease of operation is the lightened flywheel.

    I think you made one illusion to a 1974 bike? This is a 1974 R90/6? If so you need to change the gearbox, flywheel & clutch and the starter motor.

    The clutch carrier will be drilled for 11mm bolts in the crank so you have to have spacers made to accept the 10mm bolts or change the crank. Not sure what you do about the clutch carrier spacer that your early /6 doesn't have?

    It was maybe a more common operation back in the day but every time somebody these days considers it they back out. I think it's not really worth it. All this time and money spent on a 38 year old rubber cow and instead you could be riding a Ninja. :lol3
    #12
  13. ontic

    ontic

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    Aside from everything else mentioned, I followed someones advice and added a significant percentage of 'Moreys Heavy Duty Oil Stabilizer'- it is sort of like thick oily snot. There is another brand of stuff I can't recall that offers a similar product. Very noticable improvement in ease of shifting and general transmission behaviour, not just on my bike but two other pre-81 bikes as well. Worth a try IMO.

    Genrerally for me, 1'st second and back is rarely very pretty, for the 2nd to 3rd shift it gets sorted by a bit of care with preload and RPM and timing, 3rd to 4th is hard to stuff up and 4th to 5th nearly impossible to stuff up.
    Running with a broken clutch cable for a while and having to clutchless shift teaches a lot about these boxes... and 1'st to second still sucks!
    #13
  14. Voltaire

    Voltaire Titanium and Ceramic Hipster

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    Yes its a 1976 [​IMG]
    I'll probably leave it as it and live with it...My 73 R90 racebike has all the mods you speak of and yes there is no comparison. I pretend its a Ninja :rofl...Ninjacow...I like it.

    I have however collected the parts to do dual discs and a S fairing ( not the one on it, that's a junk Emgo one).
    Cheers
    #14
  15. motu

    motu Loose Pre Unit

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    When I had my /5 I'd ride around town and look to see if heads of any pedestrians turned when I changed gear - it was really embarrassing. One in ten shifts would be perfect - I'd kinda hope someone would notice that, it was such a real achievement for me.
    #15
  16. disston

    disston ShadeTreeExpert

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    I put a spare trans in my bike several years ago and rebuilt the clutch. It worked. But I was riding around everywhere like I was always angry. I would twist that wrist and rev her hard. I would bang up through the gears and again bang them down at the next light. I got really good at banging that box and only missed a gear or had it pop out of a gear or make really loud noises sometimes. Actually it would do at least one of these at almost every shift just not all of them at every shift.

    One day I was tired maybe and so was riding around kinda slow. I noticed that I was not making as much noise shifting the box and it was staying in gear, gee. So I decided I would try to relearn how to shift my trans. I practiced preloading. I shifted with purpose but not rushing it. I rode a bit slower but that did not seem a problem. I did this for several months, this slow riding and careful shifting. I was determined that every shift was important and every shift would work like it should and I could do it.

    After several months of this and I had not missed a shift or made a really loud noise with the gears for some time I decided I could increase speed. I could lead the pack again. Only I would still not miss shifts or bang fears.

    It's been much better for a couple of years now and I will miss a shift once in awhile or bang the gears once in a weeks time maybe. But not like I used to ride.

    BTW, I have a black bike and wear black leather and black shoes, I'm almost invisible but other drivers do seem to notice me. I get envious stares from guys and smiles from gals.
    #16
  17. DaveBall

    DaveBall Long timer

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    There was a time, back when these bikes were fairly new, when you could actually purchase an aftermarket lightened flywheel. Lots of people put them on their bikes, and it greatly increased their ability to hit the shifts correctly. Then there were the rest of us who just learned the preload concept, worked at it and got to the point where we were able to shift fairly quickly and reliably, without sounding like we were grinding coffee, or banging the hell out of the tranny.

    2 things I have always found useful is to preload, and use the throttle well. i.e. shift well above 3000 RPM. These bikes love to rev and hate to be lugged.
    #17
  18. Kai Ju

    Kai Ju Long timer

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    I noticed a very big difference when i went from the one piece shiftlever to the linkage set up when I made my rear sets.
    It improved some more after I replaced the bearings and reshimmed the box while I was installing a lighter flywheel.
    But the biggest difference was going to a linkage type shifter.
    #18
  19. Plaka

    Plaka Brevis illi vita est

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    The linkage shifter is sloppier but you can nail the ergonomics to get the best action out of your foot. I had to readjust mine until my boots broke in.
    #19
  20. kadesean

    kadesean eyesuck

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    I've logged probably 70,000-80,000 airhead miles. I'm glad to hear that I'm not the only one that continues to learn the art of shifting these things. I know about the pre-loading, shifting higher in the rev range, etc. Another thing I have found is that they are better once up to temp. I find that somedays they are butter smooth, but most days they require the right finesse and technique.

    When riding a motorcycle you can use the muscles in your back, throttle hand, clutch hand, etc. But on an airhead my left foot gets the most work from the careful shifting :evil
    #20