I have a R100GS 91 paralever and every now and then get oil leakage from the bevel joint oil breather, sometimes even making it's way onto the back wheel - I first noticed it when the back end slipped! It only seems to do it on long hauls and oddly enough the oil level does not seem to be going down. I thought maybe oil was making it's way out of the gearbox and down the shaft - I did find traces of oil there but the gear oil doesn't seem to be going down either! Could that get into the bevel drive anyway? My brother has the same bike, same year and has exactly the same problem.

Cheers

Mel

Sounds like it's overfilled.

On a Paralever, oil shouldn't get from the gearbox to the diff, there's a dry shaft in the way. Check it has no oil in it by undoing the gaiter clamp and pulling it back. If it's dry, the only reason the diff would be spewing oil out the breather is overfilling.

Are you measuring the oil, or using the level plug? If measuring, and you both have the same problem, it sounds a lot like you have the wrong spec. Use the level plug, with the bike on the center stand and wheels level - block the front an inch or two.

You could also be using the wrong oil. Straight plain cheap 80W-90 gear oil is all that's needed. You'll never wear out the gears, and the bearings last almost forever, so fancy oils are a waste.

The only other reason for it to spew is overheating, and that's unlikely.

------------------
Grant Johnson

Seek, and ye shall find.
------------------------

One world, Two wheels.
www.HorizonsUnlimited.com

__________________
Grant Johnson
Seek, and ye shall find.
------------------------
Inspiring, Informing and Connecting travellers since 1997!
www.HorizonsUnlimited.com

Perhaps I have some related info. Out here in the wilds of montana we occasionally have bevel gears(or diffs on the ATVs) that will spew a bit of oil out the breather. I have also had it happen on shaft drive sidecar rigs. Makes a mess but doesn't seem to lower the gear oil level much. I can usally trace it to cold rides with the gear oil being thick and forced out the breather a bit. It only takes 1/2 teaspoon of gear oil to make a mess. The ATVs have a breather hose about a meter long and the cold oil is forced all the way out the small diameter hose. I still wish I hadn't sold my R26.

Mel,

if you do find oil in the paralever shaft, even if very little, it will find its way into the bevel. The bevel only has a volume of 0,26 litre, so if only a small amount seeps down from the gearbox through the shaft it will cause the bevel to spill via the breather. Meaning that the oil seal on the gearbox is leaking.

The only other reason I can imagine is that water has entered via the breather. Does happen occasionally. Then the oil looks a bit milky and should be changed.

Hans

__________________
Only when we pause to wonder
do we go beyond the limits of our little lives.
(Rod McKuen)

Thanks for the quick replies!
I've checked the oil in the bevel by both methods - using the level plug and also by measuring it. Still seems to leak out. I guess it must be coming in from the gearbox via the shaft. The oil level does not increase but I suppose this just means the excess is coming out through the breather. Seems wierd though that the oil can get into the bevel this way and not out! Time to replace the gearbox oil seal I think.

Cheers,

Mel

Open the rubber boot in front of the rear drive and look for oil.
I was riding with a friend who was on a K75 and his overflowed. We could not find out why.
I heard of another BMW that overflowed but this one was in the back of a truck.
In both cases the K75 and the bike in the truck the bikes had just gone over very high mountain passes.
Our conclusion was that the change in air pressure and a dirty breather with an air bubble.
Ponder ?

I had the same problem on my R80GS. There oil came from a small hole over the gear-box oil seal (the hole should be plugged on paralevers).
If there is oil in the shaft it will get into the bevel house through the sealing (but not back). So if there is oil in the shaft replace the gearbox-sealing or plug the hole.

It’s smart to turn the breather backwards to avoid to fill up the brake with oil…

The gearbox has a seal on its' output to the shaft. The bevel drive has a seal on its' input from the shaft. You could have one seal leak into the drive shaft area - but not migrate through teh drive shaft from one to teh otehr - the leaked oil will stay in the drive shaft area.

I'd say you have some water in the bevel drive oil. And it is venting from the top of the bevel drive. Change the oil - there is not much of it. And I'd change it twice to get rid or the old oil - run th efirst oil for say 100 miles then change again.

__________________
---
Regards Frank Warner
motorcycles BMW R80 G/S 1981, BMW K11LT 1993, BMW K75 G/S

Have you ever tried to mount the seal in a fork upside down? It will not seal at all, it’s designed to seal in one direction… The same goes for the seal in the bevel-drive; oil from the shaft goes slowly right through it.
Believe me I had this problems for months in Sahara (no rivers and no rain) it stopped when I plugged the hole beside the oil-seal in the gearbox.

It’s also smart to check the breather in the gearbox.

AliBaba has a point which I forgot. Some of the old GS gearboxes do have a triangular opening on the top side of the hole where the seal for the drive shaft is placed.

When fitting a new oil seal, close this small opening with silicon paste.

The reason, why oil from the paralever tunnel can enter the bevel has been said already. The seals just work one way. The seal on the bevel stops the oil from oozing out into the paralever, but does not stop oil oozing into the bevel from the paralever tunnel.

Good luck with the repairs.
Hans

__________________
Only when we pause to wonder
do we go beyond the limits of our little lives.
(Rod McKuen)

Another hint: The other day I saw quite a cute solution to keep water from getting into gearbox and bevel via the breather.

The guy had fitted hollow screws on the breather holes and fixed a tube to the screws leading into the airbox. As a result you are able to ford deep water without risking to flood your bevel.

__________________
Only when we pause to wonder
do we go beyond the limits of our little lives.
(Rod McKuen)

I have the same problem. I stripped the swinging arm on my '91' R100GS to replace the rubber boot on the back of the gearbox(again!) and I released a half litre of oil from the back of the paralever.My gearbox is a recent reconditioned from Motorworks so I assume the gearbox oil seal is not leeking but where else could it come from and my gear oil is going down.I wonder if anyone has any opinions about that new oil seal that is employed at the junction between gearbox and paralever?Not only did BMW take a backward step in introducing a dry shaft but they pop in a revolutionary new oilseal that could be questionable.There was no ergency if a seal was dubious on the wet shaft because the seals where designed to have oil either side the only difference between the two(dry and wet) being ONE extra universal joint.Am I missing something or couldnt BMW have simply introduced this new joint without drying both(the engineers nightmare).Or is it you spend 80 years evolving a vehicle to perfection and then wonder why you never see the afluent purchasers again?Just a thought but annoying when all the rider wants is a 2 wheeler that when water and fuel become a luxury he is not concerned that his steed may have been designed with a wealthy commuter in mind.jem

It was after a BMW-garage (in Oslo) changed the seals my gearbox started to leak into the paralever. I got the job redone in Germany (BMW-garage) and it still leaked. In the end I saw that none of the garages had plugged the hole above the sealing between gearbox and paralever… I would have checked it (and the breathing), it’s also worth checking that the seal is placed the right way (it’s different on a GS and a G/S).

When the paralever was introduced it was filled with oil (2 plugs partno 07 11 9 919 225), and some people still do it. IMHO it’s not a smart solution.

Jem

you may have qualified for membership of the BMW owners psychological support group! dont be distressed you are on the " ultimate riding machine" remember!


alec

__________________
Close to Antarctica and a long way from reality

Alibaba

where is the gearbox breather? I thought that was the hole in the output shaft seal area.

alec

[This message has been edited by simmo (edited 07 February 2005).]

__________________
Close to Antarctica and a long way from reality