Taller 5th in a 33/11

Discussion in 'Airheads' started by ME 109, Nov 1, 2012.

  1. Wirespokes

    Wirespokes Beemerholics Anonymous

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    I agree that the pall spring is best left alone. There were other reasons for them breaking besides getting old, like binding or who knows what.

    Also, it's also possible the roller bearing instead of nylon roller isn't the best idea as it can cause wear. The nylon rollers work just fine.
    #21
  2. supershaft

    supershaft because I can

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    I have seen a couple of nylon rollers split but . . . . I have tried the metal roller and I don't like the feel of them. They make me think I am on a K bike. Oh the horror! :D
    #22
  3. ME 109

    ME 109 Long timer

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    A couple of worthy points there chaps re the feel of the metal roller against the nylon, and the wear considerations.
    I like to use my tranny 10/10, so any little improvements/precautions are most appreciated.

    Gotta pull 5th gear off to make sure whether it's a X or not.
    My bike is a 9/81 build so it should be a pre X.
    I think.
    #23
  4. ME 109

    ME 109 Long timer

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    Got the 5th gear off and it's a pre-x
    Taller 5th it will be for me.
    #24
  5. disston

    disston ShadeTreeExpert

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    I guess I'm out voted on the pawl spring. I replaced mine because that's what I was told to do when I rebuilt mine. I wasn't a member of this list then so I did not get any other advice.

    I'd really like to know why sometimes they break and other times they don't. Why do the originals from BMW last but the replacements from BMW break? But I don't hold out much hope will really know WHY? will we?
    #25
  6. ME 109

    ME 109 Long timer

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    A metallurgist with a bloody good microscope would be a start.
    Minute fracturing resulting from the initial manufacturing bending process would be my guess, as a result of etc, etc.


    I'm interested to learn how to achieve .05mm end play with .2, .28, .38 and .5mm shims. Guess I'll find out.
    #26
  7. disston

    disston ShadeTreeExpert

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    I don't know if it is a recommended way to do this but you can make those washers any size you want by lapping them properly. If you needed one .25 start with the .28, if you want one .30 start with the .38. Using a very fine sandpaper, I would do this with 1500, and putting oil on the paper on a known flat surface, the selected shim is rotated in a figure 8 pattern. Object is an even wearing of the metal by distributing the uneven forces evenly. (boy I hope I said that one right)

    I have lapped stuff this way but not those particular shims.
    #27
  8. ME 109

    ME 109 Long timer

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    Probably need two flat surfaces, both with 1500 or thereabouts and the shim sandwiched in between.
    Don't think that would be a regular occurrence with tranny rebuilds tho?
    #28
  9. disston

    disston ShadeTreeExpert

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    You also get shims in a different selection of sizes from Cycle Works. So some of theirs and the OEM shims are usually enough.
    #29
  10. ME 109

    ME 109 Long timer

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    I've started to replace bearings and have stopped at the rear bearing on the input shaft.

    How do I get that bearing off, without damaging the thin steel plate behind the bearing?

    I have changed all the other bearings (except the front input shaft)

    Agricultural urges contained thus far :D
    #30
  11. ME 109

    ME 109 Long timer

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    All bearings replaced. A little perseverance and the bearing is off the input shaft and new one in place. Note to self: don't forget to replace clutch actuating rod oil seal.

    The front input shaft bearing came out very easily and the new bearing went in just as easily with a little heating of the casing.

    The fun has just begun tho'
    #31
  12. spartanman

    spartanman regret minimizer

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    I would absolutely replace the gear. Gears are case-hardended and have a relatively soft core. Damage accelerates once you wear though the hard surface layer, which that gear has.
    #32
  13. ME 109

    ME 109 Long timer

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    Ready to set the shafts axial play. Now's the time for accuracy in measuring and interpreting.

    I don't recall any shims under the bearings at the front of the tranny........are they always all under the cover plate?

    Anyone use a sealer as well as the gasket for the rear cover?
    #33
  14. supershaft

    supershaft because I can

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    Don't forget to put the oiling plates under the front bearings.

    The measurng is a bit of a guess with the bearings rocking and whatnot. I measure from the inside race.

    I don't use a gasket. Never had an issue for it and it takes a variable out of shimming. I think they work best on the tight side. I leave the input shaft seal out until I shim them. It's easier to tell what is going on with your shim job that way for the seal sometimes dragging a little.
    #34
  15. ME 109

    ME 109 Long timer

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    I have the baffles under the front bearings.
    That's a good point about leaving the input seal out.
    Are the inner and outer races that close, so as to be able to take the shim measurement from the centre? I understand why measuring from the centre would be more accurate tho'

    I have a donor cover plate to use for measuring the shims however I'm measuring some differences in depth. I've measured three or four places around each hole and have found differences of perhaps ten thou.
    I'll need to re-asses and see if it is bearing movement that is giving me the differences, or cover plate thickness.

    I've measured my tranny cover plate and the individual pockets (when measured in three different places) are within one thou. All good there.

    If I don't use a gasket, would the Three Bond silicone that I use for barrel bases be suitable?
    #35
  16. mark1305

    mark1305 Old Enough To Know Better

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    When I had to rebuild a Ducati 900 engine after Ducati quit using the paper gasket between crankcase halves, the thickness factor decreased from somehting like a .015" gasket crushed to .011" to NIL with the Threebond (or 1194 or the equivlant). I found that to be fairly accurate when I had to split and redo the crankcase a couple of times for various other reasons.

    So for that kind of sealant applied properly (thin), I would use NIL as the thickness calculation.
    #36
  17. WacoDirtryder

    WacoDirtryder Been here awhile

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    I put the taller 5th and lower 1st in the GS i rebuilt and it sure is sweet it might be only 3 or 4 hundred rpm but we are not talking jap bike with a 13k redline it makes a huge difference i think.
    #37
  18. ME 109

    ME 109 Long timer

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    3 or 4 hundred rpm reduction will be sweet when hauling the mail I reckon.
    I've always thought that 4-5 was close ratio, so the wider ratio should work well.
    Just gotta get this shimming plate business sorted. I'm searching for one in Australia to buy......
    Anyone in Aus know a supplier?
    #38
  19. disston

    disston ShadeTreeExpert

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    I thought you said you have a junk rear cover? The idea is to machine a rear cover so it is flat on both sides and taking the outer edge off turns the bearing pockets into bearing holes. If this is done carefully enough I think you end up with a shimming plate tool. Add to this a couple of parallels and you are set.

    So all you need is a junk rear cover and I think you have machinist there?
    #39
  20. ME 109

    ME 109 Long timer

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    Thanks disston, I do have a loaner cover plate that has been machined, it is on my tranny at the moment.
    Trouble is, I'm measuring different depths on the input shaft bearing, meaning the cover isn't machined parallel?
    The cover thickness has been measured at a given point at each bearing hole, and the precise positioning for the depth gauge is marked.

    It may be as simple as taking my measurements from the 3 marked positions on the cover plate.

    I'm just concerned with obtaining the precise measurements required.

    I'm waiting to speak to the chap who kindly loaned me all the tools to fix my tranny.
    #40