Hi 
  need a bit of help/advice/information. Today I removed the rear drive to do the spline lube on my 1990 K100lt However when i got the rear drive off the drive shaft housing (swingarm) was full of oil and I also found some chewed up rubber!! (mega bummer) But the rear drive looks fine and had plenty of oil in it and the gear box oil was nearly full and had been in it for a while by the looks of it as it was black and nasty!
I have changed the oil in the rear drive and the gearbox today. any suggestions as to what could cause this and what work is involved? I am wondering if their is a seal at the back of the gearbox that is gone if so can this be fixed with just removing the swingarm? thanks in advance K.

The fact that the GB oil was black raises a few questions.

Was it the correct oil? Gear oil, especially when old should have a foul smell unlike engine oil.

Was the oil found in the swingarm the same black oil from the GB?

Was the FD oil clear?

How full was the oil in the GB? How did you measure this? There should be a C spanner in your tool kit which is used as a GB dip-stick. The GB is normally only about 25% full. If it was full to the filler cap then the GB would have developed a bit of oil pressure and oil would likely have been forced out the rear seal and ended up at the back of the swingarm.

Gearbox being nearly full could present quite a problem with oil on the rear tyre.
Here is a pic of the dip stick so you can replicate one but make sure you have a significant bend so the thing cant go down the hole. No dont ask.

Holister (KH) wrote:The fact that the GB oil was black raises a few questions.

Was it the correct oil? Gear oil, especially when old should have a foul smell unlike engine oil.

Was the oil found in the swingarm the same black oil from the GB?

Was the FD oil clear?

How full was the oil in the GB? How did you measure this? There should be a C spanner in your tool kit which is used as a GB dip-stick. The GB is normally only about 25% full. If it was full to the filler cap then the GB would have developed a bit of oil pressure and oil would likely have been forced out the rear seal and ended up at the back of the swingarm.

Hi thanks for the reply.
I have looked at the old oil and am happy that it is gearbox oil due to the smell and it is`int as black as i taught, the same with the rear drive oil.
I also changed the engine oil and oil filter and got about 4L out of the engine yesterday, (when i first got the bike I did an engine oil change but not filter got less then 3L out of it then (about 2 months and about 600 miles ago)
 
I bought a gearbox dipstick off a bmw specialist I checked the gear box before the oil change and it was just under the full mark 
I think i need to do a few miles on it and keep checking all oil levels to see what it does unless anyone can suggest anything else? thanks k.

RicK G wrote:Gearbox being nearly full could present quite a problem with oil on the rear tyre.
Here is a pic of the dip stick so you can replicate one but make sure you have a significant bend so the thing cant go down the hole. No dont ask.

Hi thanks for the reply.
I have looked at the old oil and am happy that it is gearbox oil due to the smell and it is`int as black as i taught, the same with the rear drive oil.
I also changed the engine oil and oil filter and got about 4L out of the engine yesterday, (when i first got the bike I did an engine oil change but not filter got less then 3L out of it then (about 2 months and about 600 miles ago)
 
I bought a gearbox dipstick off a bmw specialist I checked the gear box before the oil change and it was just under the full mark 
I think i need to do a few miles on it and keep checking all oil levels to see what it does unless anyone can suggest anything else? Thanks k.

heres a thought ...

perhaps the gearbox has absorbed some water ...both raising the levels , becoming rancid ...which might turn black after more than a few miles

likely culprits could be the gearbox breather ...located near the front of the gearbox and starter motor

could the raised levels weeped through to the drive shaft

most likely is the seal on the pinion of the final drive . I have also noticed some black looking goo (oily stuff )in the bottom of the swingarm to bevel box interface ...especially ..after a long ride ...with wet weather roads ...again the breather orientation could be a contributing factor

just some thoughts  that might help

charlie99 wrote:heres a thought ...

perhaps the gearbox has absorbed some water ...both raising the levels , becoming rancid ...which might turn black after more than a few miles

likely culprits could be the gearbox breather ...located near the front of the gearbox and starter motor

could the raised levels weeped through to the drive shaft

most likely is the seal on the pinion of the final drive . I have also noticed some black looking goo (oily stuff )in the bottom of the swingarm to bevel box interface ...especially ..after a long ride ...with wet weather roads ...again the breather orientation could be a contributing factor

just some thoughts  that might help

Hi Thanks for the post, i will have a look, I did see a perished pipe from the air box to the block probably a crank breeder hose so their could be others, K.

Kelvin when you say "full" of oil how much do you think there was, I see several senarios.
First it has been known for owners to put oil in the shaft housing so as to lube the spline
Second some greases will break down into a thick oily goo after some time and it is highly likely the spline was lubed with the incorrect grease and thirdly I have seen some gear oil get past a worn seal in the front of the drive only to settle in the housing, there is often a build up of the oil because the owner just keeps adding oil to the drive not realizing where the oil is going to.
I have often found oil in the housing at the bottom of the shaft and it hasn't caused a problem except that it can slowly damage the bonded rubber sleeve in the drive shaft.
If there is only 1 or 2 table spoons full in there then I would not be concerned and just top up the drive level.

RicK G wrote:Kelvin when you say "full" of oil how much do you think there was, I see several senarios.
First it has been known for owners to put oil in the shaft housing so as to lube the spline
Second some greases will break down into a thick oily goo after some time and it is highly likely the spline was lubed with the incorrect grease and thirdly I have seen some gear oil get past a worn seal in the front of the drive only to settle in the housing, there is often a build up of the oil because the owner just keeps adding oil to the drive not realizing where the oil is going to.
I have often found oil in the housing at the bottom of the shaft and it hasn't caused a problem except that it can slowly damage the bonded rubber sleeve in the drive shaft.
If there is only 1 or 2 table spoons full in there then I would not be concerned and just top up the drive level.

Hi Rick 
        Thanks for your post, After thinking about it I had wondered if someone had just put oil in the swing arm thinking that the shaft was meant to have oil in its "housing" maybe confusing it with some earlier bikes? as  the oil levels were good.
                                              The oil that came out was a bit thick "cream like" their was probably about 300ml (a pint) at best but I did`int take the shaft out so their is probably some still in their. 
                                                                         As for the rubber that came out I looked at it tonight  it has "BMW 2-20-00106-01" on one piece and "221101 BOGE" on another stamped on it when i put them together the pieces almost make a full circle (some of it is missing) I am thinking this is some sort of seal or part of a rubber booth? maybe someone will know the part number?  Thanks for your help K.

Sounds like a mix with water to make it creamy. The part number definately isnt BMW because the car part numbers start with a 2 but being that the piece is big enough to have a number on it would indicate to me that further investigation is needed.

  As for the rubber that came out I looked at it tonight  it has "BMW 2-20-00106-01" on one piece and "221101 BOGE" on another stamped on it when i put them together the pieces almost make a full circle (some of it is missing) I am thinking this is some sort of seal or part of a rubber booth? maybe someone will know the part number?


I am thinking this is your rubber damper between the spline collar and body of the drive shaft. Sounds like it has disintegrated and you have a couple of pieces of it especially as it almost makes a circle. Pull your driveshaft out and inspect it, be prepared to look for a replacement

dakelvinator wrote:Hi Thanks for the post, i will have a look, I did see a perished pipe from the air box to the block probably a crank breeder hose so their could be others, K.

I, unwittingly, power hosed my K in the early days forcing water into gearbox through the breather which lives under the battery. The result was that the breather got blocked when the water heated it turned the Oil to Mayonnaise and (presumably steam generated in the gearbox when it got hot) blew the gearbox input seal. So do check if there's water in there. In my case a new seal and cleaning the breather was all that was required, no signs of lasting damage 30k miles later thankfully.

88 wrote:

dakelvinator wrote:Hi Thanks for the post, i will have a look, I did see a perished pipe from the air box to the block probably a crank breeder hose so their could be others, K.

I, unwittingly, power hosed my K in the early days forcing water into gearbox through the breather which lives under the battery. The result was that the breather got blocked when the water heated it turned the Oil to Mayonnaise and (presumably steam generated in the gearbox when it got hot) blew the gearbox input seal. So do check if there's water in there. In my case a new seal and cleaning the breather was all that was required, no signs of lasting damage 30k miles later thankfully.

Hi thanks, this could be it when i bought the bike it clearly had been power hosed to death! I might take the swing arm off to get a better look, was the seal a hard job to do? did you have to open the gearbox?  thanks k.

Packo wrote:  As for the rubber that came out I looked at it tonight  it has "BMW 2-20-00106-01" on one piece and "221101 BOGE" on another stamped on it when i put them together the pieces almost make a full circle (some of it is missing) I am thinking this is some sort of seal or part of a rubber booth? maybe someone will know the part number?


I am thinking this is your rubber damper between the spline collar and body of the drive shaft. Sounds like it has disintegrated and you have a couple of pieces of it especially as it almost makes a circle. Pull your driveshaft out and inspect it, be prepared to look for a replacement

Hi thank for your post 
                             I think i will investigate it when i get a chance is it possible to remove the shaft and replace it without removing the swingarm? thanks k.

RicK G wrote:Sounds like a mix with water to make it creamy. The part number definately isnt BMW because the car part numbers start with a 2 but being that the piece is big enough to have a number on it would indicate to me that further investigation is needed.

Thank for your post 
                          I think i will investigate further when i get a chance i am hoping its just the rubber booth at the end of the swingarm thanks k.

Can confirm the number on the rubber which is sandwiched between the driveshaft halves.
The number should be BOGE 2-20-000-106-04.
After BMW you should also find the last seven digits from the part #, which has changed at least a couple of times.

Inge K. wrote:Can confirm the number on the rubber which is sandwiched between the driveshaft halves.
The number should be BOGE 2-20-000-106-04.
After BMW you should also find the last seven digits from the part #, which has changed at least a couple of times.

Thank you! I am very relived it is not a gear box seal! is this the rubber booth at the end of the swing arm? thanks k.

dakelvinator wrote:

                             I think i will investigate it when i get a chance is it possible to remove the shaft and replace it without removing the swingarm? thanks k.

yes,
Numerous tips on how to - use the search function. I fit a worm drive hose clamp around the spline collar and lever or tap (using a block and hammer) it off

You can get the shaft out without removing the swingarm but you will have to be a magician to get the boot on and then the shaft back in.
Take the opportunity to do some maintenance on the bearings and remove the swingarm it will be one hell of a lot easier.

dakelvinator wrote:

Inge K. wrote:Can confirm the number on the rubber which is sandwiched between the driveshaft halves.
The number should be BOGE 2-20-000-106-04.
After BMW you should also find the last seven digits from the part #, which has changed at least a couple of times.

Thank you! I am very relived it is not a gear box seal! is this the rubber booth at the end of the swing arm? thanks k.

No, think about the driveshaft as two pipes with different diameter which is bonded together with rubber.......is this pieces of rubber you have found.

It seems like you need a new driveshaft, the driveshaft can be removed w/o disturbing the swingarm.
But on one side it could maybe be a problem to get it out in one piece as the rubber have started to disintegrate.
And as Rick says it's a good opportunity to to clean and regrease the bearings....when removing the svingarm take good care to clean the threads on the LHS pivotscrew....use a toothbrush between the gearbox and swingarm.

Inge K. wrote:

dakelvinator wrote:

Inge K. wrote:Can confirm the number on the rubber which is sandwiched between the driveshaft halves.
The number should be BOGE 2-20-000-106-04.
After BMW you should also find the last seven digits from the part #, which has changed at least a couple of times.

Thank you! I am very relived it is not a gear box seal! is this the rubber booth at the end of the swing arm? thanks k.

No, think about the driveshaft as two pipes with different diameter which is bonded together with rubber.......is this pieces of rubber you have found.

It seems like you need a new driveshaft, the driveshaft can be removed w/o disturbing the swingarm.
But on one side it could maybe be a problem to get it out in one piece as the rubber have started to disintegrate.
And as Rick says it's a good opportunity to to clean and regrease the bearings....when removing the svingarm take good care to clean the threads on the LHS pivotscrew....use a toothbrush between the gearbox and swingarm.

Thanks again for your help, the rubber is off the driveshaft like you said. I will remove the swingarm when i get a chance and replace the driveshaft when i find one and also take the opportunity to do the other maintenance, It drives fine at the moment so i might leave it for now maybe do it in the winter or if i get a spare day before! thanks k.