Clutch not engaging on 1980 GS850G - solution

Discussion in 'Motorbike Technical Discussion' started by Dwarf8, Apr 14, 2004.

  1. Dwarf8

    Dwarf8 Guest

    Clutch sticking after transmission lube change...

    I posted this up a week or so ago and I'm now posting the solution.

    I changed the gear box oil on my 1980 GS850G.

    The stuff I removed was milky and it didn't look healthy at all.

    I refilled the front and rear drive units with Castrol 90 weight gear oil.
    It was limited slip type.

    When I engaged the clutch with the bike on the centre stand, the rear wheel
    turned. When I applied the brakes, the bike stalled.

    After all the adjustments were checked and the clutch opened and looked at,
    I came to the conclusion that it was just the viscosity of the gear oil.

    I started the bike off the centre stand and with me on it and slipped it
    into gear.

    With a mighty clunk, into first with the clutch in.

    It tried to creep forward but I kept the brakes on and it stayed in place
    but the revs dipped.

    Took it out for a drive.

    Hard shifting for about 2 minutes but then it was much smoother than before
    the oil change.

    I am going to replace the oil to a non limited slip formulation and re-test.

    I will post at that time.
    Dwarf8, Apr 14, 2004
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  2. Dwarf8

    Hank Guest

    The more posts I read about this, it really, REALLY, sounds like your clutch
    is running in this "gearbox" oil. Since there is little or no potential for
    savings, and a lot of potential for damage (which may have already
    occurred), why did you ever use this oil rather than the recommended oil in
    the first place??
    Hank, Apr 14, 2004
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  3. Dwarf8

    Hank Guest

    Just had a look at your "gearbox" @ It appears that, as I
    suspected, the "front gearbox" is in fact your crankcase. 90w limited slip
    engine oil! yikes!!!!

    I hope you wait awhile before you offer it for sale.
    Hank, Apr 14, 2004
  4. Dwarf8

    OH- Guest

    Could you just make things a bit more clear. I'm reasonably familiar
    with these things but have no detailed knowledge of the GS850G.
    Your description of this transmission lube change makes less and
    less sense the more you and others post about it.
    OK, this should be pretty straightforward. The gearbox, clutch and
    engine share the same oil I assume. Right ?
    What sort of oil did you fill here ? What oil does Suzuki expect you
    to use here ?
    This milky stuff came from where ? Gear box/engine ? Some other
    part of the drive train ?
    Now things get confused. I thought I understood this at first but now
    I'm not so sure.
    What is this front drive unit ?

    And your rear drive unit simply must be the angle gear set at the
    rear wheel. The G is a shaft drive, isn't it ? Or ?

    What sort of oil / oils do Suzuki recommend for these units ?
    OH-, Apr 14, 2004
  5. Did you have your bike at MSW today? I saw a big maroon 850G there at 4:30.

    Stephen Rivett, Apr 14, 2004
  6. Nope. Not necessarily.

    The GS-G has engine oil, secondary drive gear oil, and final drive
    gear oil.

    Part #60 in the diagram you linked to, is the drain for the secondary
    drive gear oil. Part # 58 is the filler plug for the gear oil.

    In this diagram: PUMP FILTER.gif
    Part #5 is the engine oil drain plug and the engine oil filler plug
    can be found as part #7 in this diagram: COVER.gif

    - Richard
    Richard C. Perrin, Apr 14, 2004
  7. Dwarf8

    B Vibert Guest

    Please tell me you didn't put 90W gear oil in your "gearbox". You
    know, the one you normally put motor oil in.
    B Vibert, Apr 15, 2004
  8. Dwarf8

    Dwarf8 Guest

    Sorry for the confusion Ladies and Gentlemen...

    1980 GS850G - Shaft drive.
    3 lubrication sumps.
    2 types of oil.
    In the crankcase (directly under the pistons where the crankshaft and clutch
    live) is 10/40 weight motorcycle oil.
    Behind that is a gear box at the forward end of the drive shaft. Recommended
    fluid is 90 weight hypoid gear oil.
    On the rear end of the shaft and sitting on the rear wheel is the final gear
    housing. Also takes 90 weight hypoid gear oil.
    LSD (Limited Slip Differential) oils have an additive that allows cone,
    clutch and viscous limited slip systems to function but is otherwise
    identical with regular hypoid gear oil. That is why I was surprised by the
    problem I was experiencing.
    I think I'm going to swap it over to a synthetic with a lower first number
    so it will be thinner before it warms up but still provides protection once
    it's hot.
    The 80/90 Castrol in there now is thick enough to stop a bullet at zero
    I am guessing the reason the original gear oil was milky was because a
    "Molly Slip" or other type of additive had been mixed with the oil for
    better shifting.
    I will continue to report back as I work on this ...
    if only to add to the confusion :)
    I really do appreciate all the replies as it is tough to figure these things
    out sometimes and input from lots of biker brains always finds a solution.
    Dwarf8, Apr 15, 2004
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