R60/5 rebuild nears completion – with some puzzles. . .

Discussion in 'Airheads' started by Tin Woodman, Feb 3, 2013.

  1. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    After living in the country for almost 25 years last month I finally broke down and bought a tractor. A 3-cylinder, diesel, ancient, gray market Japanese tractor. And, yes, it's a lot like working on an R-bike. Verified.

    :rofl:lol3:rofl

    --Bill
  2. Plaka

    Plaka Brevis illi vita est

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    If you don't know squat about tractors how do you know working on an airhead is like working on a tractor????
  3. skipn

    skipn Been here awhile

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    Don't know anything about working on airheads, so I have a lot in common with tractors.
  4. Lornce

    Lornce Lost In Place

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    You just said a mouth full.

    :augie
  5. Plaka

    Plaka Brevis illi vita est

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    True dat. Tractors don't know about working on airheads either. :1drink
  6. Tin Woodman

    Tin Woodman Mike

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    Couldn't I simply red Loctite it into place then promise never to use my kickstart?
  7. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    You could, if it's loose. But drilling and tapping for the safety stop is like a belt and suspenders-- extra protection. And as long as you have the back cover off anyway, this is the best time.

    Whatever. :D

    --Bill
  8. Tin Woodman

    Tin Woodman Mike

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    Minor discovery but at least I now know why the transmission was binding. First discovery was a red herring -

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    Bearing on intermediate shaft was misaligned. Couldn't figure out how it had been shimmed in that condition and fit in the case. Turns out it had slipped on the shaft when I heated the case and removed all three shafts. Next I tried to simulate how the dogs are aligned through all the gears. I would imagine the pro's are rolling their eyes - feel free to tell me I'm completely off track. This is first gear -

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    Neutral -

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    Second -

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    Third -

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    Fourth -

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    All the gears spin smoothly on the output shaft except for first - it's seized on its bushing. With great effort, I can spin it. It's obvious now that's been the problem all along. Sheesh!

    Now that I'm focusing on the output shaft, I realize the other bushings are worn and the gears have a lot of play. Clearly, I need to replace all the bushings.
  9. Tin Woodman

    Tin Woodman Mike

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    My motivation is curiosity I suppose. The binding first gear was really bugging me so I went ahead and pulled it and the outer ball bearing off the shaft. There was no evidence of scoring or damage to the bushing at all. Much to my amazement, when I remounted the gear, it spun effortlessly on the bushing. No play whatsoever.

    What little literature is available about 4 speed rebuilds tends to focus on ball bearings and end-play shimming - not bushings. Picked up a couple from my supplier and was shocked that they're more expensive than ball bearings -

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    I'm assuming they're bronze or Oilite (coincidentally, the Oilite trademark is owned by Beemer Precision, no connection to BMW that I can see). Still can't understand why there was so much friction (virtually seized) before vs. after. Could be the nature of bronze or Oilite.

    Put the output shaft back in the transmission housing and realigned the forks - now silky smooth through all 4 gears and neutral.
  10. Lornce

    Lornce Lost In Place

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    This is a great thread.

    :thumb :thumb
  11. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    Interesting demo of the shift dogs.

    Odd about the first gear bushing running tight. I can't remember much about those bushings. Not surprising about their cost, though. The fit a gearbox that's been out of production for 40 years and nothing else. The bearings have many other applications.

    --Bill
  12. Tin Woodman

    Tin Woodman Mike

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    Turns out the binding of first gear was caused by good ol' fashioned friction - new first gear bushing was too wide and old one was too narrow. I believe when the transmission was last rebuilt, one step was overlooked. It explains why many parts including all the bearings, are good. I'll explain. When I removed first gear I didn't notice the thrust washer showed signs of heat (notice the blue marks.)

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    When the gear was on the shaft, the original bushing was just barely proud of the gear surface.

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    When the ball bearing was pressed on, it applied too much pressure to the thrust washer with the resulting wear -

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    I'm sure what some of that 'magnet plug fuzz' is. Put a new bushing on with lots of clearance -

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    Unfortunately, too much clearance -

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    Either the bushing I installed is the wrong part (according to the fiche, it's correct), or the I have a version of the tranny with a thinner first gear (doubt that's the case). Will check with my parts supplier next week.

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    This all began when I started doing the calculations for shimming the shafts and discovered this discrepancy. The manual (and BMW, for that matter) don't provide specifications for bushings and the bushing for 2nd and 3rd gear is not user serviceable.

    Good point, Bill, about these parts. When I said, 'I picked up a couple of bushings', I really meant I paid for two with one still to come on back order - arrival status is 'indefinite'. I'm not complaining - I was already warned not to venture into transmission repair.
  13. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    Good job of sleuthing.

    The parts availability is one reason I'm farming out the next rebuild/refresh of my transmission to someone who is a master. They'll have donor boxes and/or know how to source these obscure parts. I'll gladly pay for someone's headache...

    --Bill
  14. disston

    disston ShadeTreeExpert

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    I hope you do a 5 speed some day. But the 4 speed is entertaining. Nice to compare the differences I guess.

    I wonder if we aren't supposed to just make our own bushings? This doable and quit simple if you have a lathe I think.
  15. Tin Woodman

    Tin Woodman Mike

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    For a while, I was wondering the same thing until I realized the spiral oil channel on the OD limits how much material can be removed. I'm thinking the wrong part got into my suppliers' parts bin.

    Quite agree but I think the biggest challenge in doing your own transmission repair is getting the output flange off (and back on again).

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    (photo used with permission of Joerg Hau)
  16. Tin Woodman

    Tin Woodman Mike

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    Special thanks to Pokie who I met at Akabeton's recent tech day - he shook me out of my stupor and gave me some valuable pointers on transmission setup which filled in some knowledge gaps (and he came all the way from Colorado to set me straight). Bottom line - fascinating experience, not for everyone but learned a lot. Check one more thing off the bucket list. Besides getting the output flange off and on, probably the biggest challenge was getting accurate measurements for shimming the end play on the three shafts.

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    Had my local dealer re-torque the output flange this week - didn't charge me a dime. I offer the following photos as proof progress has been made this week. Feel free to point out obvious screw ups (yes, those shocks are temporary).

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  17. Plaka

    Plaka Brevis illi vita est

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    I only see one, and a comment.

    If you use the modern footpeg rubber the kick start lever won't clear it. kick it over and the lever cuts the rubber right down to the steel. I trimmed a couple rows of diamonts off my /5 lever. Looked completely stock if you didn't know how long it used to be and worked perfectly. Might still have it even. Should have a pic somewhere.

    There is a small hole in one of your top cover badges. It has been added. drill through the top cover and put a flat head screw in it with a nut on the inside or better, drill and tap the cover for a flat head screw. You have to pick your spot carefully for a screw and nut because of the flange on the inside, so may not be able to use that hole. Anyway those badges fall off and you don't notice..at the time. I used tiny stainless button head screws on mine. looked right and I didn't have to paint them.
  18. Tin Woodman

    Tin Woodman Mike

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    Good eye, Plaka. Hopefully I'll never have to use the kick start - I was actually tempted to leave it off the bike. Installed it with a new tapered retaining pin anyway - just trying to keep it all original. In a pinch, I guess I could bump start it if I run the battery down.

    Previous owner pop riveted the badges on. I drilled out the rivets, cleaned up the badges, filled the holes with Bondo and repainted them. Then I glued them onto the cover with construction adhesive which hydraulically popped out the Bondo when I squished the badges on. Those suckers will NEVER come off again.
  19. Tin Woodman

    Tin Woodman Mike

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    I've moved onto less interesting final details like troubleshooting and correcting dodgy wiring. No photos because you've all seen it before. Did, however, stumble upon a cryptic diagram describing cable routing through the rubber grommet under the gas tank - yes, all those holes have a purpose.

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    Also figured out how to get a consistent patina on aluminum cases that I had cleaned with a wire brush and were just too bright.

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    I simply applied some of this stuff and buffed it out by hand - took minutes.

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    Even the carbs got the once-over -

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    Sometimes I marvel at the ingenuity of the designers of these machines - even though the German mantra was, 'form follows function' they still pulled off some remarkably beautiful designs. I confess to a weakness for boxer engines - they make a lot of sense. I was in Vegas recently and dropped into the car museum at the Imperial Palace where I saw, among other things, an old Panhard from France. Very BMW-like engine - no doubt lots of ideas were shared (cheerfully ripped off). This led me to reflect on boxers past and present - Daimler, Chevy (Corvair), Alfa Romeo, Subaru and of course, Porsche. (Name a few more - I'm sure there were lots.) It was a Porsche engineer, Hans-gunther von der Marwitzm who was lured to BMW in the mid-sixties to revamp the /2 line and create the /5 line. I see a lot of BMW DNA in my Porsche.

    The reason I dredge up this seemingly irrelevant stuff is my belief that half the fun of riding an airhead is understanding its history. I often wonder about the mentality of its original creators. For those of you who haven't seen it, check out Porsche's movie from the 1960's called Made by Hand (it's on YT). Pure Porsche propaganda but it gives some insight into the design philosophies of post-war German manufacturers. Very interesting.
  20. Tin Woodman

    Tin Woodman Mike

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    For those of you who have followed this thread patiently and who have put up with the gloomy photos, I offer something a bit more uplifting - after almost three decades in boxes the bike's first glimpse of sunshine. . .

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    Just a few more parts and it will rejoin the fleet. Cheers.

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