Telltale drip pattern on a rear wheel?

RhysU · 06-14-2021, 06:25 AM

'Morning.

I've a 99 R1100S with just under 78K miles on it. Partway through a recent trip to Vermont (ride 8A in northern Massachusetts!) I noticed the pictured drip+dirt pattern on the rear wheel.

Something spinning appears to be oozing slowly, centripetal etc is throwing it to the wheel surface, and dirt is adhering. On inspection, I don't see any obvious source for the fluid (but I'm all thumbs). I've not noticed any reduction in rear braking or anything else glaring amiss.

This pattern looks like it's got to be a standard telltale for something specific needing love. Any ideas? Or, any specific things to rule out?

Thanks in advance,
Rhys

908/930 · 908/930's Garage

I would think it is the pinion gear seal is worn and it is gear oil, pull the rubber boot back and take a look in there. Or the shaft seal on the crowngear, is there any play on your rear tire?

WilyB · WilyB's Garage

Centripetal is highly unlikely.

JimMoore · 06-14-2021, 10:56 AM

Pull the boot back and see how much is in there. If it's a little bit, clean it up and forget it. If it's a lot, then we need to investigate further.

s-thing · 06-14-2021, 03:34 PM

Quote:

Originally Posted by JimMoore

Pull the boot back and see how much is in there. If it's a little bit, clean it up and forget it. If it's a lot, then we need to investigate further.

+1 for Jim’s thoughts. My gear gearbox output seal weeped a little and looked like this. Maybe a teaspoon+ of oil inside the swing arm. Came and went for many miles. Replaced seal when doing other service and gone for good,

More notable oil in swing arm or anything from the final drive warrants further inspection.

Long shot but if you have older rubber brake lines check for pinholes/ballooning. (Would expect more even coverage from fine spray)

Jim W

brentw1 · brentw1's Garage

looks like chain oil,

what the others said or check you dont have a brake hose or caliper leak

jimmy-d · 06-17-2021, 03:24 PM

@RhysU, I have a 99 R1100S with 27k miles, and your post made me check my bike. I did a 300-mile ride on Monday and I see similar drip+dirt on my rear wheel.

Checking the bottom edges of the rear drive boot, I have oil that collects then drips down. I'll pull back the boot later to see how bad it is, but it doesn't look like much.

Something else to consider is the fuel overflow hose. When I travel I like to fill the tank to the very top when I stop for fuel. My R1100S is black and I was riding in 95° heat with cloudless skies Monday. In my case, fuel may have expanded in the heat, overflowed, and created the crud on my wheel. Sorry I wiped it down before the photo, but you can still see some of the residue on the link rod.

RBMann · 06-17-2021, 11:11 PM

Pull your rear wheel off and check the big seal on the final drive. Mine looked just like yours. Look at post #14 on this link-

http://forums.pelicanparts.com/bmw-r1100s-r1200s-tech-forum/558109-driveshaft-more-love.html

RhysU · 07-08-2021, 08:41 AM

Thank you all for the advice.

mophead · 07-08-2021, 12:36 PM

I just replaced my rear drive oil seal due to leakage. Its on a 2001 model. About 20K mileage so age has something to do with it also. There was quite a bit of grunge on the part of the drive where the seal meets the turning drive (where the lug bolts go). I got a wire brush and cleaned all the grunge off before installing the new seal and so far no more leaks. Have had the bike out for a short run of about 10 miles or so and no leakage.

I did use a CR seal for replacement instead of the BMW made of gold seal. Bought it off ebay for $12 and free shipping.