R100GS Gearbox Repair

Discussion in 'Old's Cool' started by Suppermotodd, Jan 5, 2007.

  1. Suppermotodd

    Suppermotodd Tag Thief

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    I am rebuilding my BumbleBee trany and found this double sealed bearing in the mix. The new bearing is not sealed at all and would seem to be correct choice. I also noticed that this is the only SKF bearing in the gearbox. Have any of you run into this before? Is this a factory screw up or has the gearbox been worked on before?:huh

    [​IMG]

    :ear
    #1
  2. StephenB

    StephenB G(/)S ... what else!

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    Been worked on before is my best guess as they are all open C3 or C1 (?).
    #2
  3. Suppermotodd

    Suppermotodd Tag Thief

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    Here are a few pics of the bearing replacement. All you need is a 20 ton press and a BFH.:D


    [​IMG]



    [​IMG]
    Big Orange Country! GO VOLS!:clap

    [​IMG]

    BFH


    [​IMG]

    Output shaft is done!:D
    #3
  4. Boojum

    Boojum I Miss the PartyBoss

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    Yea! :wings that one is done!! Get that Beyotch back together, man.:lol3


    Boojum!
    #4
  5. datchew

    datchew Don't buy from Brad

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    you put a pillow under the press right? he he he.

    At first glance I imagined the gears and shaft bouncing off the concrete floor. :eek1
    #5
  6. Suppermotodd

    Suppermotodd Tag Thief

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    I put rug and coat under it. Just in case I droped it!:eek1 :lol3
    #6
  7. AntonLargiader

    AntonLargiader Long timer

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    I list the various tranny bearings on my website:

    http://www.largiader.com/tech/airtrans/
    #7
  8. friar mike

    friar mike IronButtGruver

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    yep Snap-on sockits thay have so many uses.:lol3
    #8
  9. Suppermotodd

    Suppermotodd Tag Thief

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    #9
  10. Suppermotodd

    Suppermotodd Tag Thief

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    It was the only thing I had that was the correct size. I felt really bad banging on that high dollar socket but what's a man to do?:dunno
    #10
  11. GSPD750

    GSPD750 Adventurer

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    As an alternative to banging and risk damaging the bearing would be to heat the bearing and leave the shaft in the freezer for a 1/2 hr.
    Mating the two then should only require minimal tapping on the bearing or assemble it back in the press.

    I recently replaced the timing chain crankshaft sprocket which req'd a 3 jaw puller and considerable effort to get it off due to the shrink fit.
    To install the new sprocket I placed a bag of snow around the crankshaft nose for a 1/2 hr and then heated the sprocket.
    The sprocket then "dropped" onto the crank by hand. A lite tap on a socket ensured it was home...but it already was.
    #11
  12. datchew

    datchew Don't buy from Brad

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    if you get crazy with heating/cooling
    I find that dry ice with the part in a cooler works well.

    Just gives you a few more degrees than regular ice or your freezer.
    #12
  13. datchew

    datchew Don't buy from Brad

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    I've been following info on tranny rebuilds closely cause I'd like to do one someday when I get a garage.

    Many folks with their online how-to's make it look so much easier than the book does. Books show tons of feeler gauge-ing and etc.

    When you press the bearings on, do you simply press them until they seat to a pre-machined groove on the shaft or do you have to measure it? If there's a "seat" on the shaft, that seems to me to be pretty easy and the rest is just measuring to check for wear tolerance.

    Can the circlip groove be cut into the shaft with the gears still on the shaft as long as the bearings are removed? Could a local machine shop do it if you give the right measurements?

    I guess like anything else, it seems like a bunch of voodoo until you get your hands on one.
    #13
  14. Middleweightboxer

    Middleweightboxer Middleweightboxer

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    Your critical measurements come when determining the proper shim stack thickness for the shaft end play.

    The sealed bearing mentioned in the earlier message is becoming a common practice. The late model BMW transmissions used sealed bearings. The theory is you keep all the metal bits out of the bearings that way. Some mechanics are rebuilding our older transmissions using all sealed bearings.
    #14
  15. datchew

    datchew Don't buy from Brad

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    I guess i'm torn on that method. You not only keep the metal bits out, you keep the fresh fluid out also. Granted, sealed bearings, especially roller bearings, last a very long time. But if you're good enough to change the fluid regularly, I have to say, I'd probably feel better about the non-sealed bearings.

    Can you give more info on the shim stack thickness?
    #15
  16. Joerg

    Joerg Long timer

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    Hi,

    (and Happy New year, btw ;-)
    The issue of "sealed" vs "non-sealed" is a long story ... but first, don't forget that that even the so-called "sealed" bearings do not offer a hermetic closure; it's more a plastic lip that covers the bearings' sides. One technical reason is probably that the "closed" bearings were supposed to keep their oil over a longer time, however the old /7 gearboxes reportedly did not use this "mix" of bearings.

    Here you are, including a spreadsheet to calculate what you need: http://homepage.sunrise.ch/mysunrise/joerg.hau/mot/gearbox.htm#adjust ... the whole process is difficult to visualize from a description, but once you are presented with an open gearbox it all becomes sooo obvious :D
    #16
  17. datchew

    datchew Don't buy from Brad

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    You're the man Joerg. Either i'm blind or you've updated your site, or you have stuff hiding from me.

    I missed that on your site somehow. Thanks.
    #17
  18. Joerg

    Joerg Long timer

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    Last update of the gearbox page was 2006-11-26, which <i>could</i> mean that a visit to the optician <i>might</i> be due :lol3
    #18
  19. datchew

    datchew Don't buy from Brad

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    Could you just start typing in a larger font?:evil
    The average age of the bmw owner is like 50-something right? he he he.
    #19
  20. Middleweightboxer

    Middleweightboxer Middleweightboxer

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    The link to the web site is great. That is the way it is done.

    We have a local mechanic that will assist home rebuilders with measuring and getting the shims correct for a small donation.

    I believe Ed Korn sells some clay that can be placed between the bearings and the cover. You bake the transmission to cure clay then remove the cover and measure the cured clay to establish the existing clearances. If you don't have a measuring plate available this is a fall back procedure. Here is Ed's listing:
    MOLD-A-GAUGE
    Non stick, non shrink, heat cured material, used to measure the end play of the input, intermediate, and output shafts on the /2 /5 /6 /7 R26 R27 and probably other BMW transmissions. Has to be heated to 275F (135C) for 25 minutes (oven). You will need a caliper (preferably dial) to measure the thickness of the cured MOLD-A GAUGE. Replaces Matra numbers 504 5061 and BMW 23 3 650. Enough for at least 4 transmissions......$7 (0.1 lb)

    This is a good method for the home rebuilder. Good luck.
    #20