Was ist das?

Fixxxer · 10-17-2007, 12:19 PM

Can anybody tell me what this black stuff is on my rear wheel (pics below)? For what it's worth, I'm still pretty new to bikes in general, and I've only owned this one a few months (it's a 1999 R1100S +ABS with ~35,000 miles).

It's mostly on the drive-side of the wheel and it seems to appear after I take a long trip (~150 miles with very few stops). If I clean the wheel up and take a bunch of short rides, like 20 miles back and forth to work, I don't see much, if anything, on the wheel... It's really only noticeable after a single long trip.

I changed the rear drive fluid the day before I took my last ~150 mile trip, so if that's what was leaking, I don't think it would be as black as what I'm seeing. It doesn't really feel like oil either... There's not enough of it there to get a good "feel" of it, but it doesn't seem to be as runny as oil.

It looks like it could be originating where the wheel meets the final drive, but it's really hard to get a good look in there without taking the wheel off (which I have not done yet).

Could it be rear brake dust collecting and then just flinging out to the outer-rim of the wheel? If not, what else could it be?

(Sorry about the picture quality -- I had to take them with my camera-phone.)

Thanks!

YellowRacer · 10-17-2007, 12:52 PM

Looks like oil... Ohh no. Someone might have a final drive leak...

jduke · 10-17-2007, 01:42 PM

If it was thinner and more fine threads of it, I would think it's brake fluid, but it's probably coming from your rear end, the dark color is dirt that stuck to it. When you changed the rear end gear oil, you probably put a little too much in and it "burped" out the vent. Clean it off, drain the rear end again, and this time make sure you don't put too much in. I usually stop when the fluid gets to the very bottom thread.
If it continues, you probably need to change the rubber O-ring in the rear end. Very easy to do.
Good luck!
Jerry - Savannah, GA

BrandonS · 10-17-2007, 01:53 PM

Did you recently take you wheel off and put it back on with too much anti-seize?

OpenBoatt · 10-17-2007, 02:04 PM

Brandon, are you saying rear wheels lugs should be installed with anti-seize? That's not a practice I'm familiar with. Is that recommended? I was always taught wheel lugs should be bone dry and clean. Am I in the stone age here (as usual)? tom

Rimmy · 10-17-2007, 02:12 PM

My vote is also final drive leak.

Sideshow_S · 10-17-2007, 02:19 PM

Fixxxer,

Do yourself a favor. Pull the wheel. It's 4 bolts on the rim and two on the brake caliper. If you have a centerstand, this can be done in 5-10 minutes (as a novice). Check the big seal around the wheel's mounting face. If there's any leaking, replace that ASAP. It will be a minute fraction of the cost if it happens to fail on you and you don't see the oil because of the rain 800 miles from your garage.

Rapid Dog · 10-17-2007, 03:02 PM

Der Big Seal Mine Betinzee

Bob Hancock · 10-17-2007, 03:15 PM

What sideshow says and don't use anti-seize. Lightly clean the threads with a wire brush and torque dry.

wswartzwel · 10-17-2007, 03:21 PM

Flattbutts bike was doing that, and the ring of allen screws around the perimeter of the big seal, that hold the rear housing together were loose.

BrandonS · 10-17-2007, 03:38 PM

Quote:

Originally Posted by OpenBoatt

Brandon, are you saying rear wheels lugs should be installed with anti-seize? That's not a practice I'm familiar with. Is that recommended? I was always taught wheel lugs should be bone dry and clean. Am I in the stone age here (as usual)? tom

I dont but I was just trying to rule out simpler less expensive problems.

shreddr · shreddr's Garage

it is obviously the "black oil" from the final episodes of X-Files! Whatever you do, don't get it in your eyes!!!

John Lyon · 05:08 PM

Quote:

Originally Posted by OpenBoatt

Brandon, are you saying rear wheels lugs should be installed with anti-seize? That's not a practice I'm familiar with. Is that recommended? I was always taught wheel lugs should be bone dry and clean. Am I in the stone age here (as usual)? tom

That's what I thought too, but when I recently took off my wheels for new tires, I saw that the BMW shop had put blue (medium) thread lock on the rear lugs. I did the same, in spite of what the manual says. Roger and others have expressed that any threaded parts "low" on the bike should be protected from the elements in this way, and blue is removable with just hand tools (no heat) so I went with it.

There was a huge argument here about whether this a good idea on the clincher bolts on the bottom of the forks too (which I did as well). Hope this doesn't start it up again.

Boybiker3 · 05:26 PM

I think oil can also work its way out of the vent assembly, esp if the FD or whole bike has been on its side.

But from the pattern of dirt, it looks like the leak is associated more closely with the wheel than with the FD and in fact closely resembles the pattern you'd see if conventional wheel bearings (which are not present, of course) started leaking oil or water-stuff.

Sometimes dirty water can get into and/or be temporarily trapped in the big cavity inside the crown wheel shaft outside the FD and under the wheel hub - ugly rusty water like after a power washing.

There are lots of good reasons to do up wheel lug nuts (bikes and cars) dry but these tend not to apply to conscientious owners. Likewise, there are good reasons to use anti-seize (or possibly blue Locktite) there and these do apply to conscientious owners. Think for yourself.

Fixxxer · 05:42 PM

Thanks for the info guys!

I've never had the wheel off, so I don't think it could be anything on the lugs that's flinging-off. Also, the bike has never been on its side.

I just did another quick finger test of the black stuff, and it's very dry -- almost powdery. As someone suggested, it looks like some oil has gotten on the wheel and then dirt/brake dust has collected on it.

I'm going to be out of town this weekend, so I won't be able to work on it at all, but I'll plan to pull the wheel off and check the ring of allen screws and the big seal sometime next week.

Can anyone post a pic of the seal that I'm looking to inspect/replace? (I just did a quick check of the repair manual and didn't see it.) Also, do any of you know the part number for said seal? I'll probably run up to the dealership next week and pick one up, just in case.

foobeemer · 10-17-2007, 05:42 PM

If the final drive seal looks ok I would guess it may be brake fluid from the overflow hose that hangs down with road grime/brake dust stuck to it.

Boybiker3 · 10-17-2007, 06:01 PM

Quote:

Originally Posted by Fixxxer

I just did another quick finger test of the black stuff, and it's very dry -- almost powdery.

Then it must have gotten there carried by something that evaporates like water, gas, etc. Any sign it was eating your wheel paint?

John Lyon · 10-17-2007, 06:07 PM

Quote:

Originally Posted by Boybiker3

Then it must have gotten there carried by something that evaporates like water, gas, etc.

That's a good clue. Perhaps some water from the road, etc. just collected the brake pad dust into this pattern. My bike does this from time to time, but not always. I think you just helped me figure it out.

CREOLA · 10-18-2007, 03:25 AM

Too much chain lube.

Bob Hancock · 10-18-2007, 04:07 AM

Quote:

Originally Posted by John Lyon

That's a good clue. Perhaps some water from the road, etc. just collected the brake pad dust into this pattern. My bike does this from time to time, but not always. I think you just helped me figure it out.

I get something like this, especially at the front where there's more brake dust, everytime I wash the bike and take it for a spin before it's totally dry. Could be just that. But good to check that rear seal too.