Clutch not engaging on 1980 GS850G - solution

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.

 

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??

 

Just had a look at your "gearbox" @
http://www.bigshaftie.fsnet.co.uk/CRANKCASE.gif. 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.

 

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 ?

 

Did you have your bike at MSW today? I saw a big maroon 850G there at 4:30.

Steve

 

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:
http://www.bigshaftie.fsnet.co.uk/OIL 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:
http://www.bigshaftie.fsnet.co.uk/CRANKCASE COVER.gif

- Richard

 

Please tell me you didn't put 90W gear oil in your "gearbox". You
know, the one you normally put motor oil in.

 

Hahahahahaha...
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
celsius.
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.