black deposit on rear wheel

[britguy]

Bike has about 1800 miles......When I rode the bike home from the 600 mile service I noticed some black deposits on the brake side of the rear alloy wheel....... didnt notice it before 600 but never really looked.
There seems to be a collection of it around the inside of the final drive flange and from there its being thrown onto the wheel rim.

I was thinking that it may be deposit from the brake pads.......is this normal....or could it be something like an oil leak from the final drive?
[/i]

[DJ Downunder]

I was thinking that it may be deposit from the brake pads.......is this normal....

yes, yes, yes...that's what I think it is..we all get it...it's hard to tell without pics.

DJ

[britguy]

I was thinking that it may be deposit from the brake pads.......is this normal....

yes, yes, yes...that's what I think it is..we all get it...it's hard to tell without pics.

DJ

Thanks.

Just cleaned my bike so unable to show pictures at this time!

[Dauntless]

When the mechanic changed the FD fluid, he probably got some on the wheel while draining. Brake dust then got stuck to it. If it comes back after you wash the bike you might have a leak.

[Dan-A]

If it blows off, or wipes off easily, brake dust, and normal. If it is lubricant, not normal, at least on mine.

[Ray R]

I've had this same issue on mine since new. I wipe it off and it comes back after about 200 miles. It's not oil becasue it wipes off easily. It's not brake dust, becasue I get the dust even if I don't use the rear brake. None of my other BMWs do this. I found this post on another forum:
The rear wheel bolts to a "flange". The flange has "splines" that run 90 degrees to the direction of travel. The flange attaches to a matching set of splines on the rear axle tube of the final drive. It's a compression fit. If sufficient wear occurs on either, or both, set(s) of splines, you may find that the only thing holding on your rear wheel is a small circlip! When mine failed that way, once the circlip was removed, the entire wheel/flange assembly came off without any resistance whatsoever. Pretty scary to think I was two-up with a full load at the time. First thing I noticed was black residue on the wheel, somewhat like brake dust. Obviously it was fine metal particles coming from the two mating pieces wearing away.They replaced my final drive (flange comes with the FD), rear rotor and all lug nuts. That was all covered by warranty (July 2007), and was the subject of a technical service bulletin (for the 12GS at the time -- early 2005).

I'll be taking it to the dealer.......

[RonR]

I've had this same issue on mine since new. I wipe it off and it comes back after about 200 miles. It's not oil becasue it wipes off easily. It's not brake dust, becasue I get the dust even if I don't use the rear brake.

I would guess that it is brake dust. You, and all of us, have linked brakes where the rear is activated along with the front without you touching the rear brake pedal. One reason why the brakes are so good.

[Ray R]

The other reason I'm pretty sure it's not just brake dust is becasue none of my other 2007 R bikes exibit the same symptom. And this dust seems to hit the wheel in droplets that leave a tail. When I've seen brake dust, it's spread more evenly over the rim. I'm also seeing MUCH more of this dust on the rear wheel, and none on the front.

[Ray R]

I got the bike back from the dealer, and no trouble found. The flange was not loose and everything seemed in order. They're a good dealer, so I trust their findings. I have only 1500 miles on it.

That said, I still wonder where the dust is coming from. My bike DOES NOT have linked brakes. I don't have ABS and I can spin the rear wheel with the brake lever squeezed. I can ride without using the rear brake and the dust still appears.

I'll ride it until it breaks.

[lewellen]

I got the bike back from the dealer, and no trouble found. The flange was not loose and everything seemed in order. They're a good dealer, so I trust their findings. I have only 1500 miles on it.

That said, I still wonder where the dust is coming from. My bike DOES NOT have linked brakes. I don't have ABS and I can spin the rear wheel with the brake lever squeezed. I can ride without using the rear brake and the dust still appears.

I'll ride it until it breaks.

Um, I think all of the R1200R series have linked brakes, e.g. the rear brake is 30% applied when you apply the front brake. This is an independent feature from ABS. In fact, I think I remember reading a rather emphatic caution against doing rear-wheel spins on the R12Rs. You can do it - the engine has enough torque to overcome the somewhat weakly applied rear brake, but it's definitely not good for the rear brake. (Or the tire, for that matter).

But, whichever. I'd be happy, personally, without the linked brake system myself, so if yours is, please let me know who your dealer is and how you managed to get one like that, as I'd like to have the non-linked arrangement as well.

Back to the original question, I have the same spatter-pattern thing on mine, with the small caveat that it noticeably appears more on one side of the wheel than the other (in my case, about 120 deg. past the valve stem has the most concentration of spots). My dealer (BMW of Santa Cruz) also thought it might be a little grease / oil left from the 600 mi service, and did a thorough wipedown & checkout of the area. Didn't find anything, still happening. The spots look like spatters, but they wipe clean with a rag more like dust than oil.

My hypothesis is this: The brake dust tends to build up in clumps in the ventilation holes. When a clump lets loose, it hits the rim on the right-hand side and we see the "thrown Ziploc bag of talcum pattern" impact pattern from it hitting and spattering. In my particular case, either the rear disk is very slightly warped or is thinner on one side than the other, accounting for the asymmetry in the splatter pattern.

... which is irritating from a keep-it-clean standpoint, but not really indicative of a major mechanical problem.

Has anybody changed out the rear pads with non-OEM? If so, do you still see this?

Good roads,

- Lewellen

[Ray R]

With the bike on the centerstand, engine off or on, spinning the rear wheel by hand and applying the brake handle. My brakes are not linked. It's a 2007 model. I ordered it from the dealer. It's nothing special. I followed the brake lines...not linked.

[gibbo111]

same here 2007 no ABS not linked

[Lost Rider]

My hypothesis is this: The brake dust tends to build up in clumps in the ventilation holes. When a clump lets loose, it hits the rim on the right-hand side and we see the "thrown Ziploc bag of talcum pattern" impact pattern from it hitting and spattering. In my particular case, either the rear disk is very slightly warped or is thinner on one side than the other, accounting for the asymmetry in the splatter pattern.

Has anybody changed out the rear pads with non-OEM? If so, do you still see this?


- Lewellen

That hypothesis sounds very plausible...

I have been running EBC pads on my R for a while and I still get those spots - on the right side.

[silvermcoupe]

This may also be a silly question but I am curious. I have an 08 R12R with ABS. When I use the front brakes does it apply equal pressure to the front and rear brakes? Should I also apply the rear brakes at the same time? Just a little confused?
Thanks for the info.

[deilenberger]

This may also be a silly question but I am curious. I have an 08 R12R with ABS. When I use the front brakes does it apply equal pressure to the front and rear brakes? Should I also apply the rear brakes at the same time? Just a little confused?
Thanks for the info.

Hmmm... I believe you asked this once already. It's not equal pressure. You don't want equal pressure since under braking your weight transfers forward, requiring more pressure on the front brake.

And should you apply the rear - why? The electronics/hydraulics can figure it out much better than you normally can. I rarely use the rear brake at all - mostly just for trail-braking on sharp low speed corners to "set" the bike for the turn.

[lewellen]

And should you apply the rear - why? The electronics/hydraulics can figure it out much better than you normally can. I rarely use the rear brake at all - mostly just for trail-braking on sharp low speed corners to "set" the bike for the turn.

While I disagree with Master Eilenberger only reluctantly....

Linked brakes and other advances such as ABS, traction control, and so forth, generally provide increased safety and control for the rider. No arguments there.

I still like to apply the rear brakes "manually," both in usual riding and in the situations Don mentioned above, for two reasons. First, occasionally I ride other bikes, which do not have linked brakes. Making a note to use the rear brake on the R12R keeps me in good practice for when the brakes aren't linked.

Second, I find that even with the weight transfer, under hard braking with the hand brake, I can still "get more" out of the rear wheel; the linkage should be set up this way, at any rate. When (not if) I ever need a fast, hard brake, I don't want to have to spend another half-second to think about it and move my foot to the pedal.

It's the same reason I hit the horn when I'm in tunnels ... oh, wait, that's just fun.

Good roads,

- Lewellen