1993 R80GS Gearbox Oil Leak

[MikeH101]

I've needed to top up the gearbox oil a couple of times over the 3,000km I've done since purchasing the GS. Doing some work today I noticed an oil build up under the gearbox, just about visible in the pic. Any suggestions what the likely cause is?
The bike is due a service in a couple of weeks and I'll get advice as to the severity and repair plan.

 

[Stirlingmoz]

I had gearbox oil leaking through a neural switch recently.

Bit the bullet and pulled the gearbox out to replace it.

Seemed easier than trying to fit a new switch with gearbox still fitted - though it can be done.

 

[DrFarkoff]

@Stirlingmoz is Right Likely a neutral switch

2 ways to do it Both best done with the gear oil drained

Gearbox out New prop bolts needed etc etc

If you can "move" the rear through bolt Engine mounting ???

Support the rear of engine with whatever you want? With the load spread on a bit of plywood perhaps ??

So the bolt is out Next knock out the spacer tube between the outer edges of the sump Obviously this wants to be done sensibly and don;t break anything!!

You then have fairly good access to the neutral switch Which is disconnect the wires

unscrew and remove it

replace it with a new one and a new sealing washer !!!

Now Getting the tube back in If you stick it in a bucket of water with ice it will chill down for 15 mins and if you are fairly quick you can get it back in without too much phaff

When I did mine I filed a slight leading edge on the side I intended to push in to the space again Just a few mm wide so that it is not absolutely square and hard to get started

IF it goes cock eyed?

Just stop remove it and set up again

Don;t force it !!

 

[scooter paul]

Highly likely it’s the neutral switch leaking. No need to remove gearbox. You just need to remove the rear engine mount bolt enough to get the spacer out. The spacer can be a tight fit though.

 

[Gelandestrasse]

There’s a couple of checks before you go for the neutral switch. Check the oil that you see is gearbox oil or engine oil (sniff test). If gearbox oil the likely the neutral switch is leaking as said above.
If it is engine oil then that’s the rear crank seal gone.
If it is engine oil and you are still losing gearbox oil (part of me so longs to ask how you know it’s low on oil) then check your breather bolt on the gearbox and if there is oil in the shaft/swingarm. Is the output shaft seal in the correct way round?

 

[MikeH101]

I'll take the bash plate off tomorrow and check if there are any signs of source and give it a 'sniff' test.
I noted the low oil by removing the filler plug and the level is down below the thread.

 

[MikeH101]

Closer examination today shows the neutral switch is soaked with gearbox oil. At least I now know which repair job is required.
Thanks for the hints.

 

[MikeH101]

Looks like the gearbox oil leak has another symptom. I noticed the bevel box oil was seeping out of the filler plug and breather. Loosening the drive shaft to bevel box gaiter resulted in oil running out. So it seems likely the gearbox output shaft seal is damaged and needs replacing, aswell. I've worked out a plan with Steve at Rainbow so he can fix what's immediately necessary when booked in for major service next week and return later for more serious gearbox out job.

 

[Gelandestrasse]

Check your breather bolt of the gearbox. If it is blocked, oil will be forced past the rear gearbox seal into the shaft and then bevel and you get the symptoms you just described. Check the breather bolt, it could save you a fortune in money and a whole load of time.


It's happened to me before....

 

[MikeH101]

Taken the earthing bolt/breather out and checked it is clear, no blockage.
Thx