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I bought my 02LT with just over 11K miles on the clock. I put synthetic gear oil in the FD at 14K miles. I noticed some oil seepage at the rubber boot about 4 weeks later, opened it up and had around 2 tablespoons of oil in the boot but the final drive casing back toward the engine was dry. It looked like it had come from the front FD seal. I thought, maybe these BMW seals don't like synthetic or maybe the seal was leaking from sitting. I changed out the FD oil with dino and just pulled the boot at 36K miles and there was no leakage inside. I have always filled the drive to the threads without turning the rear wheel. What are your thoughts, oil or age?

And NO, I don't want to start an oil thread/war.


John
 

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Being new to LTs, I have been reading all that I can and there are a myriad of opinions as there usually are on oil and tire threads. However, I will be very interested to see the replies/comments.

FWIW, I have been using Amsoil Severe Gear oil (can't remember the weight) in the FD in my RT for 20k miles now with no problems.
 

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RockyRaccon said:
.... I noticed some oil seepage at the rubber boot about 4 weeks later, opened it up and had around 2 tablespoons of oil in the boot but the final drive casing back toward the engine was dry......
John
Did you mean to say "swingarm housing" rather than "final drive casing" here? Otherwise I'm having trouble understanding your description.

Oil found at the rubber boot between the final drive and the swingarm housing isn't all that uncommon. The source is either the tranny output seal or the FD input seal as you suspect.
No, synthetic oil isn't bad for the seals. However, synthetic is a little more "leaky" since the molecule size is smaller than that of "dino" lube.

You probably have a slightly leaky seal. It isn't impossible for a seal to leak and then stop leaking when the leak is due to some particulate matter that gets caught at the seal lip and then clears itself. Unusual, but it does happen. More likely I think is that you will see a little more leakage over time even with non-synthetic lube in there.

Many folks have just observed the leak over time rather than fix it since it can be very slow. Replacing the seal isn't that hard, I've done a few. It does require a special tool and very high torque so you need a way to secure the FD during removal and installation of the locking ring that secures the seal.
 

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CharlieVT said:
Replacing the seal isn't that hard, I've done a few. It does require a special tool and very high torque so you need a way to secure the FD during removal and installation of the locking ring that secures the seal.
I just got back from Daytona BMW and they want $500+ to replace the final drive seal and the gear box seal.

I went in to have them put on a new front ME880 and they said I need new seals.

I looked in the service manual and searched the forums and could not locate a guide for replaceing the final drive seal.

Any pointers or link would be appreciated
 

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pauleknight said:
I just got back from Daytona BMW and they want $500+ to replace the final drive seal and the gear box seal.

I went in to have them put on a new front ME880 and they said I need new seals.

I looked in the service manual and searched the forums and could not locate a guide for replaceing the final drive seal.

Any pointers or link would be appreciated
They say you need both tranny output and FD input seals? What are the odds of both or 'em leaking? Maybe they are both leaking or maybe Daytona just is taking the shotgun approach. What the heck, I wonder what else they can replace while they're in there.
Seriously, I'd check the pivot bearings while the FD is off the bike.

My suggestion is to determine where your leak is. Is it the FD input seal or the tranny output seal. Okay, maybe it really is both. There are some methods to try to determine which. Use different color lubes in the FD and tranny. Then see what color ends up in the swingarm boot. Or if a significant volume of lube is showing up in the swingarm, check level in the FD and tranny; the one losing fluid level is the leaker.

For the tranny input seal, search for the clutch slave weep hole instructions, that'll get you close to the tranny output seal.

For FD input seal replacement, I haven't seen anyone post the method. It is in the BMW service manual and it isn't all that easy. You'll need a special tool (I got one from a local autoparts store and modified it with welding and grinding to fit). And because of the torque values, you'll need a way to secure the final drive to remove and replace the highly torqued retaining ring that must be removed to get the seal.

I work on final drives as a hobby of sorts but now charge a 100 bucks for my time and shop supplies in addition to parts costs. Most of the drives I work on end up costing folks $200-300 after shipping, parts and all. I'd be no help to you with the tranny seal but you could do that when the FD is off if it is needed. If you sent me the FD for changing the input seal, I'd check the crownwheel bearing for preload too. Send me a private msg if you'd like my help with the FD. If you want to tackle it yourself, it isn't really that hard, you just need to source the socket, figure a way to really stabilize the final drive (it is another special tool in the BMW service manual, but I use a heavy duty workbench and a combination of vice and big C-clamps. If your table isn't quite heavy or bolted down, you'll flip the table over trying to remove the retaining ring.)
In summary, things you'll need: special socket for the retaining ring, breaker bar with a "cheater" to remove the retaining ring, a way to secure the FD while doing that. BMW specified Hylomar sealant for sealing the threads of the retaining ring when installing the new seal. Torque wrench to reinstall the retaining ring. I think that's it.... if you have other questions, I'll try to help.
 

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CharlieVT said:
Use different color lubes in the FD and tranny. Then see what color ends up in the swingarm boot. Or if a significant volume of lube is showing up in the swingarm, check level in the FD and tranny; the one losing fluid level is the leaker.
The funny thing is that they claimed to check both fluid levels and saw that neither fluid was low.

I was unable to work on the bike last night (family committments) when getting back from Daytona yesterday night.

I will check things out today. Maybe get different color fluids and see what comes out.

Paul
 

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On my first LT('05) I had the same problem. I told my wrench and he said that most of the leaks they saw were from overfilling the FD. It just comes out. I have since started putting a little less in that it calls for(220 or 225 cc) and normally there is no leaking. I even used a straw one time(straw into the oil and finger over the top of straw) to remove some of the oil and that stopped the leak. It does not take much to make it leak.
That's my story.
 
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