Final Drive Leak

WrecklessRalph · Post by **WrecklessRalph** » Mon Aug 20, 2007 2:22 am

Gentlemen (and ladies),

I need a little help. My 2004 1150R has 13,000 miles on it and the last ride I noticed that the boot on what I believe to be the swing arm (you can see how mechanicaly inclined I am) seemed to be leaking onto the rear wheel. I felt the bottom of the boot and it was wet with fluid, but it was not dripping. I checked the fluid level and it was still level with the bottom of the fill hole. I called Max's BMW of N. Hampton, NH, and they said that I would have to bring it in and it was not something that I could do. Apparently there are several seals in there and they would have to take it apart to determine which was leaking. I have Mobil 1 75-90 in there now. I have heard rumors that it is the synthetic oil that caused the leak. Any truth to this? Is there a possibility of me doing the repair (I have done more things to my bike since reading all the posts here--things I never dreamt that I would do. I just recently did my 12K mile service with your help and she runs better than ever!)

Thanks for any help or advice.
Ralph
Kingston, New Hampshire

Post by **DJ Downunder** » Mon Aug 20, 2007 2:54 am

Hi there Ralph...g'day and welcome.

Don't worry too much about it...Mine has done it on and off over the years and have done nothing.

Just give it a good clean (wipe it down with a cloth)..and just keep an eye on it..If it starts to drip and leak alot maybe have the rear seal replaced.

Others here may know more about this problem.

DJ

Post by **12bar1** » Mon Aug 20, 2007 4:02 am

I just had the same thing happen to me and I followed the advice of cleaning it up and watching it. So far no more leaks, I think what happened in my case is it was a minor leak that I never noticed and the area collected a lot of dirt mixed with a little oil.

Post by **Biff's R** » Mon Aug 20, 2007 5:17 am

I have had several bouts with this. I have had the FD seal replaced twice, and the output shaft seal from the Transmission replaced once.

You can just keep an eye on it. What is your situation with your warranty? I would also stick to dino oil in the FD.

Byrdguy · Post by **Byrdguy** » Mon Aug 20, 2007 6:35 am

Mine (with 14000 miles) didn't seep until I changed the fluid to synthetic. I've heard several reports of this happening with the synthetic fluid. I'm going to change back to regular 75-90 and see what happens. A friend with a Moto Guzzi had the same problem and regular fluid solved his problem. You may want to do the same. I'm going to do the same with the trans fluid also, because if the tranny seals leak, oil could get on the clutch.

Post by **TicTac50** » Mon Aug 20, 2007 8:51 am

Just clean the boot and replace the the rear with the red color oil.
Next time you see the boot wet, probably after 300 to 500 miles, take a clean cloth and check for the color of the oil inside the boot. You will know if it is leaking from the front or from the rear. If it is the rear, you can do the job your self but your will need the special tool to pool that seal out. I took mine to the BMW shop. Total cost $165.00 Do not worry about to much. Just keep an eye on it and do not ride with out the oil.
Good luck.

Post by **ProductUser** » Mon Aug 20, 2007 10:32 am

Synthetic oil in the FD has absolutely no bearing on your FD leaks. How do I know? Well, I've been running synthetic oil in my R for the last 50 thousand miles and have had ZERO problems. Oh, and a lot of other BMW riders have also run synthetic oil and have had zero problems.

I'm making this claim based on newly developed synthetic oils

One other thing: I've read that readline shockproof oil may have caused some issues with oil venting through the breather, however, there doesn't seem to be enough data to substantiate that claim.

Perhaps your breather vent is plugged? Did you over fill your FD? There are lots of reasons why FD's leak oil.

ProductUser

Post by **CycleRob** » Mon Aug 20, 2007 12:26 pm

Member ProductUser is correct. I have been using full synthetic gear oils since the 600 mile check, over 50,000 miles ago, with zero leaks anywhere. The only leak my bike has ever had was the Ohlins rear shock seal !

Full synthetic engine oil was started at the 18,000 service, when it stopped using oil. Those two examples cover how oil seals handle changing over to synthetics with both low and high mileage.

There may be some cases where oil leaks started after using synthetics, but there's not enough good data to support a ban.

R4R&R · Post by **R4R&R** » Mon Aug 20, 2007 1:04 pm

CycleRob wrote:There may be some cases where oil leaks started after using synthetics, but there's not enough good data to support a ban.

Funny thing, my local BMW club seems to be following a trend that switching to synthetic in the final drive, causes leaks. No real data, only heresay.

I think any good brand oil (synthetic or dino) will be good and not cause leaks. I have a feeling that overfiling may be the cause...

Post by **Boxer** » Mon Aug 20, 2007 1:28 pm

My masseuse switched to synthetic massaging oil and it caused me to have to go TAKE a leak. But I doubt if that has any bearing on this thread...so just ignore it.

def38 · Post by **def38** » Mon Aug 20, 2007 5:31 pm

Synthetic GL-5 oils do not cause leaks. Synthetic oils have very high resistance to shear, tolerate heat better and usually conatain a good anti-oxidant additive...all good reasons to use synthetics. I use 75W-140 GL-5 in both the transmission and FD. Now, moly does help reduce seal damage...I use moly as well in both gear cases.

Finally, when you first drain your gearcases, thoroughly flush them with ATF. This will carry away any small abrasive bits that WILL ruin seals.

Post by **NoRRmad** » Mon Aug 20, 2007 10:44 pm

It could be due to detergent content; I tried a high-detergent oil in my old Ducati years ago and had a lot of seepage around various gaskets afterwards. It was explained to me by somebody who ought to know that the oil had dissolved crud on the inside of gasket-sealed surfaces, allowing leakage.

Post by **DJ Downunder** » Tue Aug 21, 2007 6:56 am

I was told by an oil expert that a good synthetic oil does three things.

1..lubs 2..cools 3..cleans

It's the last one that causes leaks in old engines that has crud and gunk around the gaskets...and then when the new oil cleans that away they can leak.

That should never be a problem on our engines.

I've heard that our rear drive shaft runs very, very hot...and good synthetic oils handle the heat much better than dino.

DJ

def38 · Post by **def38** » Tue Aug 21, 2007 9:20 am

Remember, we're talking gear oil here...no combustion by-products to cause sludge or ash...synthetics can help to reduce shear, produced when gears beat up the oil molecule.

Correct;

1- Cool.
2- Lube.
3- Clean.

Changing gear oils helps to remove any debris. There is no filter in our gear systems.

geothepencil · Post by **geothepencil** » Tue Aug 21, 2007 9:50 am

DJ Downunder wrote: I've heard that our rear drive shaft runs very, very hot...and good synthetic oils handle the heat much better than dino.

DJ

You will note that the R1200S bikes currently being raced quite successfully have the rubber boot missing on the back of the driveshaft housing just for that very reason.

geo

WrecklessRalph · Post by **WrecklessRalph** » Wed Aug 22, 2007 2:32 pm

Thanks for all of the replys. I am a fan of synthetis oils. All of the testing done by engineers that I have read support their superiority. I did go to Max's BMW and the gentleman in the service department told me to move the boot forward and if it leaks oil, then the seals need to be replaced. I also read about the vent hole--I am unable to find one. Where is it located? I have been out for three rides averaging abou 100 miles and no further leaking.

Thanks again for all of your support.

Ralph
Kingston, NH

Post by **iowabeakster** » Wed Aug 22, 2007 5:11 pm

The vent is directly on top of the FD. 12 o'clock position. That small cylinder sitting on top is the cap.