Oil leaking from final drive

[peb]

Walked out to the bike after a meeting yesterday only to discover oil on my rear wheel. After inspection I determined that it was coming from the final drive(rear end). I just happened to be about 5 miles from the BMW dealer, so I took a quick look at the tire, no oil on it, hoped on the bike and rode gently to the dealership.

 

They agreed to take a quick look. Long story short, I had too muck oil in the final drive and it was coming out the vent. I understand this, but here is my question. It has been over 15,000 miles since the oil has been changed. What took it so long to leak out? The bike has been exposed to all temps.(hot and cold weather) plus long and short distance rides(5 miles to 1000 mile days).

[Ken H.]

What lube did you put in it? Some of them, Red Line in particular, are known for foaming in the FD, causing leaking out the vent.

[Gail]

My best guess is that moisture has accumulated in the rear drive unit through condensation. Moisture will cause the oil to foam thus increase its volume. Temperature changes are a primary cause of condensation. Personally, I would consider changing the rear drive oil each time I change the engine oil. That way you can purge any moisture, plus you have the opportunity to check the status of the drive unit (watch for metal flakes in the oil which would indicate bearing failure.

 

Gail

[peb]

I'm not sure which brand. That service was done at a BMW dealership in another state. I could assume it was BMW stuff, but I don't like to assume.

[4wheeldog]

Mine did this a couple days (and a couple thousand miles) before it grenaded. Hope this isn't the case for you. Good Luck!

[flat_twin]

Walked out to the bike after a meeting yesterday only to discover oil on my rear wheel. After inspection I determined that it was coming from the final drive(rear end). I just happened to be about 5 miles from the BMW dealer, so I took a quick look at the tire, no oil on it, hoped on the bike and rode gently to the dealership.

 

They agreed to take a quick look. Long story short, I had too muck oil in the final drive and it was coming out the vent. I understand this, but here is my question. It has been over 15,000 miles since the oil has been changed. What took it so long to leak out? The bike has been exposed to all temps.(hot and cold weather) plus long and short distance rides(5 miles to 1000 mile days).

 

Did the dealer just check to see where it was coming from or did they replace the gear oil? If they didn't, change it soon. 15k miles is too long. Drain the old stuff into a clean container so you can examine the fluid. The rear drive is the easiest fluid to change on these bikes. I change mine at more regular intervals since my final drive failure last year.

[peb]

The dealer changed the fluid and said that the fluid looked fine. Just had too much in there. Thanks for all the information from the above responses.

[KMG_365]

BMW has recognized a problem with the older FD's which contained a 19-ball rear wheel bearing (aka crown bearing). This appears to have been the cause of the numerous FD failures, most notably in the LT's since they have the most load on the rear wheel. The new 17-ball bearing should address this problem.

[Mike_H]

I suspect you may have a bearing in your final drive going bad causing the final drive to overheat which in turn caused the final drive vent to pop open to relieve pressure. I can't see how it could have been overfilled if you hadn't added any fluid in 15,000 miles.

 

My final drive bearings gave out on me (2000 RT), but it was a few more thousand miles after the leak(s) before the bearing finally gave out. When it did I could feel grinding/vibrations through the footpegs while riding ... ground my way 50 miles back home that day.