[skotlyc]

So a little bit of final drive fluid leaked out when I removed the rear tire. Mainly through the bold holes... is this normal?

 

[sheldan2]

Not normal. Your seal might be starting to go, very strange, sure it is not water from a recent wash, ride in the rain etc? The bolt holes do not go through to the final drive fluid.

 

[64deville]

skotlyc can you tell me if your rear rotor had any play left to right when you removed

 

[skotlyc]

no play in the rotor or the rear end at all. Everything seems tight. Its not water either from washing, its purple... It is definetley final drive fluid.

 

[sheldan2]

Some times fluid will escape through the breather at the top of the final drive. Clean it up well with brake cleaner, check your fluid level in the final drive, ride it for a couple of days and re check everything. If fluid is there again, might want to change the seal.

 

[Dick]

Some times fluid will escape through the breather at the top of the final drive. Clean it up well with brake cleaner, check your fluid level in the final drive, ride it for a couple of days and re check everything. If fluid is there again, might want to change the seal.

Might be some good info on fluid leaking thru rear tire bolt holes here. Look for recent posts by John Zeiler.

 

[CharlieVT]

Might be some good info on fluid leaking thru rear tire bolt holes here. Look for recent posts by John Zeiler.

Dick, I had a sinking feeling reading my old post in that thread. One of my biggest misstatements regarding final drive when I blamed oil coming out the wheel bolt holes on there being too much oil. I was really WRONG!

If anyone is going to read that thread, read the WHOLE thread. There is a learning process going in the thread and the truth doesn't start to come out until many posts down.
Here's post #24 in that thread:
http://www.bmwlt.com/forums/showpost.php?p=441240&postcount=24

Here's a much more informed post on the subject:
http://www.bmwlt.com/forums/showpost.php?p=588063&postcount=4

 

[sheldan2]

Thanks Dick, I stand corrected.

 

[CharlieVT]

So a little bit of final drive fluid leaked out when I removed the rear tire. Mainly through the bold holes... is this normal?

What year bike and how many miles?

You want to confirm that the oil is really coming out the bolt holes.
As posted above, oil can come out the breather at times.

If the hub seal is leaking, is is very rare for the problem to be just the seal. There is most likely an underlying bearing problem associated with a leaking seal. This issue can be fixed by rebuilding the drive with a new bearing and seal and PROPER setup of the bearing preload.

If you are correct, and lube is really coming out the wheel bolt holes, you have a know failure that is very expensive to repair as it will need a new crowngear/pinion gear set (>$600 for parts) and then the drive will need a total rebuild. Not cost effective, buying a new or used replacement drive makes more sense.

Oil leaking out the wheel bolt holes is associated with a lack of interference fit between the steel and aluminum components of the crowngear. These parts are pressed together at the factor and supplied as part of the crowngear/pinion gear set. I've never heard on anyone trying to repair that part. Another characteristic sign of this kind of failure in addition to lube coming out the bolt holes is aluminum suspended in the lube; the lube will be quite dark.

If you confirm that you have lube coming out of the wheel bolt holes, the drive should be disassembled to confirm the looseness between the components of the crowngear. I'll bet they are loose, there is no other explanation for lube coming out the bolt holes that I know of. (barring catestrophic fracture of the crowngear assembly, but then you'd probably have a loose, wobbly rear wheel).

Sorry for what is potentially bad news for your final drive.

 

[skotlyc]

My bike is a '99 with 68000mi on it. It was a very small amount of oil out of the bolt holes only when the bolts were removed. No other leaking up until I removed the bolts completely. Should I paste it back together and ride it till I notice play in the rear end? No other explanation... (anything PLEASE)? You can lie to me if you like...

 

[CharlieVT]

My bike is a '99 with 68000mi on it. It was a very small amount of oil out of the bolt holes only when the bolts were removed. No other leaking up until I removed the bolts completely. Should I paste it back together and ride it till I notice play in the rear end? No other explanation... (anything PLEASE)? You can lie to me if you like...

Scott,
I've studied and posted about FD failures as much as anyone on this site and have posted many times about the type of failure that you are experiencing.
Oil coming out the bolt holes is characteristic of (or pathognomonic for :histerica) this type of failure.
Yes, you can ride it but for how long, no one knows. And, while there are very few cases where circumstances suggest that someone got hurt because of a final drive failure, it could happen.
In my opinion you should start looking for a used FD to replace yours; ride yours until you get a replacement. As I posted earlier, the kind of failure you are experiencing is a prohibitively expensive repair.
If you post on this site that you are looking for a replacement FD for a 99, someone may have one. They also show up on eBay with some frequency.

 

[skotlyc]

alright... thanks everyone, I'll start looking.

 

[wa1200lt]

One last addendum to CharlieVT's comment about riding until it fails. Don't ride any further from home than you are willing to push it. About 5 feet for me.

Loren

 

[copperstatetour]

If it turns out to be a FD Failure don't forget to register it as many forum entries have suggested:

http://www.bmwlt.com/forums/showthread.php?t=66194

Registering these things helps us all :soapbox:

 

[CharlieVT]

One last addendum to CharlieVT's comment about riding until it fails. Don't ride any further from home than you are willing to push it. About 5 feet for me.

Loren

I probably should clarify, whenever someone has symptoms of the "classic" crownwheel bearing failure, my advise IS to stop riding at once or risk further damage to the FD. AND the crownwheel bearing failure won't go very far once the vibration, grinding, etc. are felt by the rider, and it won't go far before the hub seal tears and FD lube is on the rear brake and tire.

However, the failure type that I suspect in this thread IS NOT a crownwheel bearing failure. It will probably go hundreds of miles as the crowngear assembly slowly wears aluminum. So the reason I suggested that he continue to ride while he searches for replacement are several fold: 1) His drive is toast anyway, cost of repair of that failure, done professionally, would cost as much as a new drive from BMW. 2) The failure is a slow going one. The early signs are oil coming out of the bolt holes during a tire change. I know of only a few of this type of failure, but it seems to take a long time for the wear to progress to the point of altered ride sensations. 3) This type of failure isn't known for dumping lube on the rear wheel. Eventually, the crowngear assembly will become wobbly inside the FD housing, at that point the hub seal may begin to leak, but it will probably be an oozing rather than a huge dump of lube as happens with the crownwheel bearing failure.
I'm not incouraging that the bike be ridden, I'm just saying it could be ridden for a while with relatively low risk. Obviously, if ridden, the bike should be ridden with great caution, and save the canyon carving for the new final drive.
HTH

 

[WildBill]

I just had this happen to me. I have a 2008 with 44K miles on it. As I was replacing the tires so that I could take the bike to the dealer to replace the clutch I noticed oil coming from the lug nuts. As CharlieVT said it was a failed rear drive. It was a total loss and required a total new rear drive to be shipped from Germany. So I had to replace both the clutch AND the rear drive at only 44K miles. This is the 3rd rear drive I've had to replace, 2 on my other LT. My wife, who's taking it better then me, said I need to treat it as a consumable and just plan on replacing it periodically. For a bike that works so well everywhere else it sure is a shame the rear drive is such a weak link.

Bill

 

[skotlyc]

Took a 240mi trip on Friday (beautiful here in Indiana), came back and pulled a couple of the lug nuts out, and oil is now pouring from the bolt holes. After reading some of the other posts, am I to understand that the Steel Crown gear is separating from the aluminum hub assembly which is causing the oil leak? If this is the case, Has anyone ever tried to braze them back together? If one were to drill and place dowel pins between the steel gear and the aluminum hub for radial support, and then braze the two together for axial support would that work? I'm not the best welder and know just enough to keep myself out of trouble, but I have friends that do it as a profession and they work for beer.

 

[CharlieVT]

.....am I to understand that the Steel Crown gear is eparating from the aluminum hub assembly which is causing the oil leak?......
.....Has anyone ever tried to braze them back together? If one were to drill and place dowel pins between the steel gear and the aluminum hub for radial support, and then braze the two together for axial support would that work?.......

Yes, the steel crown gear has the aluminun seat for the tapered roller bearing pressed into it. Engineers on this site have suggested that BMW did this so heat expansion/contraction of the crown gear assembly would match the heat expansion/contraction of the final drive housing.
And yes, when this press fit is inadequate, the parts begin to slip with respect to each other allowing oil past the interface. As it continues to wear the parts will become looser and unstable with respect to each other. This results in increased risk for bearing damage, and allows oil to past through the interface faster.

No one has ever repaired one that I know of. But nothing is impossible. I once posted here that a post 2005 FD couldn't be converted to an earlier configuration with a hole for the speedometer sensor, but someone on this site proceeded to do just that; so I've learned never to say "never". Welding or brazing aluminum to carbon steel...hmmmm. Drilling and pinning will also weaken components.

The "fit up" of the compents will become increasingly difficult so you should stop riding on it now. You should probably stop riding in any case, bad things could happen as the crown gear assembly becomes increasingly unstable. And if you do attempt repair, I think you'd want an experienced machinist to check and make sure the tapered roller bearing seat (aluminum end) and the crown wheel bearing seat (steel end) are concentric after your repair.

I wouldn't be all that confident in a repair, I'd be wondering about it all the time riding on it. Also make sure you rebuild the drive checking the crownwheel bearing preload. It is likely that things will have changed because of the wear that is going on and the bearing set up should be checked and adjusted as needed.

It would not be impossible to rebuild that drive. You could find a used FD an take the crowngear/pinion set from it. However, it would be much easier to just find a used drive, and check it to make sure it is set up right.

 

[skotlyc]

I did find a used drive on ebay. It makes me nervous though with 115k miles on it. The gentlemen claims he has always kept synthetic in it, and has never had any leaks or signs of failure. He is asking $400 for it, is that a good price? I personally thought it was about $100 high for having that many miles on it. Should I rebuild it with new bearings before I install it? Sounds like its probably a better option than repairing the one I have.

 

[CharlieVT]

I did find a used drive on ebay. It makes me nervous though with 115k miles on it. The gentlemen claims he has always kept synthetic in it, and has never had any leaks or signs of failure. He is asking $400 for it, is that a good price? I personally thought it was about $100 high for having that many miles on it. Should I rebuild it with new bearings before I install it? Sounds like its probably a better option than repairing the one I have.

Seems high priced to me. I'd want to pay no more than $200 for that drive.
And yes, the drive should be rebuilt, not just by replacing the crown wheel bearing, but with inspection of the tapered roller bearing, the input pinion needle bearing for race "creep", and then if all checks out okay, rebuild with new crownwheel bearing with measurement for proper preload shim thickness.