Replacement rear brake rotor

[Paul-from-VA]

Has anyone replaced the rear brake rotor with an aftermarket unit? If so can you tell me brand, source and price?

[mogu83]

I'm starting to have questions about the rear brakes on my R1200R also. It seems like the rear pads are wearing much faster than the front ones. I don't think it's riding style because I have three bikes on the road and don't have a problem with the others. I'm using the BMW organic (stock) pads. At first I thought it could be because the holes in the disk weren't chamfered and the sharp edges were using up the pads. BUT - the GS and RT use the same disks and I haven't heard of any issues. Maybe the proportioning valve is set too heavy for the rear brakes. Or maybe it's just me.

BTW: the back pads were gone (metal to metal) at 16,000 miles. The fronts look almost new. I'm usually pretty easy on brakes.

[deilenberger]

Harry,

As we discussed on Sunday - I got about the same miles from my rear pads (but caught them just before metal to metal..) And I've spoken to a number of other people with the same experience.

I'm gonna go to an R1200RT specific forum and see what sort of miles they're getting.. I'll report back..

[Paul-from-VA]

I did find replacement rotors at beemerboneyard. I also think I found the cause of the warp. The pin holding the pads in place (think capital letter L) was facing the wrong way, toward the driveshaft, causing the inner pad to hang on the caliper and drag all the time. This also caused the pad to wear out very quickly. I asked the local dealer for some help, waste of time, he could not find anything wrong even though I could visually see and feel the rotor high spot just turning the wheel. If you don't have access to a compenent dealership this bike could be expensive to support.

[mogu83]

I put a dial indicator on my disk and it's dead on. I figured that could be a problem.
BTW: The dial indicator has a magnetic mount. Trying to find some steel on this bike is a real task. No wonder it's so light.

[NeilS]

As was said elsewhere, and assuming you have the ABS, the system expects you to be braking only with the front brake lever and calculates the amount of rear pressure to apply. If you're using "conventional" hand-and-foot braking, that means you're over-braking the rear wheel. This can explain premature rear pad wear, as well as excessive brake dust on the rear wheel.

[mogu83]

Neil,
Interesting and reasonably logical explanation. I guess I'll have to accept it. You don't work for a dealer do you?
Changing reflex's developed over 45+ years of riding aren't going to change fast and seeing as I ride other bikes I'm not sure I'll try to change them. Looks like I better stock up on rear brake pads.

[deilenberger]

I'm not certain what the difference in the R vs RT brake systems is.. but the one report I got from a 2007 RT owner on the other forum was - he had replaced the front pads at 16k, the rear were still the original at 29k. Obviously - something is significantly different. Mebbe have to find a GS forum and ask there..

[Bill Stevenson]

On my 2002 R1150R the brakes were ABS and that was the first year of the integrated brakes if memory serves. I always felt that the pressure on the rear was excessive on that bike and to back that impression up, the rear pads needed replacement every 10,000 miles or so. The ABS used to kick in occasionally when it was not expected too. On previous non-integrated ABS brake equipped Beemers (two K bikes), my rear pads lasted for 50,000 miles or so and the ABS was much less prone to kicking in. My R1200R has only 8,000 miles on it now so am not sure what to expect with it, although it feels much better and ABS has not kicked in at all except when I tested it. I think BMW needs to rethink the integrated brake set up as I am pretty sure that is the primary reason why rear pads are wearing so quickly. Frankly I don't care for integrated brakes.

Bill

[lowflying]

Can anybody help me with this one?

At 16000 km I've just started to hear a metallic noise from my rear brake. I was kind of expecting it as just having returned a year or so ago from a 22-year break, I've been taking a bit of time getting used to low speed maneuvres and been practising a lot in car parks. I've probably been a bit heavy on the back brake doing that while getting the old feel back. Also I think I have been using a bit too much back brake generally as I haven't relied on the proportioning that's automatically done for you when using the front lever. A couple of thousand km. ago I changed my habits and now do brake (mostly) with only the front lever and find the proportioning works quite well, although I always pull up to that final stop transitioning to using back brake for the last few feet as I find it's a smoother stop with less dive, and more comfortable for the passenger too.

Anyway, on inspecting my rear pads it seems that the inboard one is down to the backing plate and the outboard still has a few millimetres left. Anybody have any ideas why that would happen? Shouldn't they wear symmetrically? Apologies if this has been covered elsewhere as I've been a bit busy (riding too!) and haven't taken the time to research this...

[lowflying]

Hmm. I noticed Paul-from-VA's post (30 Oct 08) above and did another inspection. It seems I may have a different problem then he did as my "L-shaped pin" looks to be pointing inboard (away from the driveshaft) and is inboard of the inboard pad backing plate. Is that as it should be?

I'm still baffled about the assymetric wearing of the rear brake pads.

[deilenberger]

The pads do NOT wear unevenly - the inner one is thinner when new than the outer one. The only reason I can think of for BMW to do this is - there is a hole in the center of the inner pad that will show the disk when the pad is almost worn out. That is how BMW expects you to check pad wear quickly. And they probably make that pad thinner so it opens up the hole before both pads are fully worn out.

[lowflying]

Thanks Don. I just wonder why they would do that. Why would I want the inboard one to be down to the backing plate and the outboard one still having good material left? If they do make them different thicknesses wouldn't that be the outcome every time?

Took it into my dealer today. He said that the assymmetric wear was not uncommon as "the pistons apply more force on that side". Seems to me that the caliper, by design, would even out the force on both sides? Otherwise more force is being applied to one side of the rotor. Surely that's not ideal?

Anyway, it's being fixed and I am now nervously awaiting the outcome (the bill)...

[enderw88]

Took it into my dealer today. He said that the assymmetric wear was not uncommon as "the pistons apply more force on that side". Seems to me that the caliper, by design, would even out the force on both sides?

Isn't that a floating caliper? I sense a gross conceptual error on the part of the dealer...

[deilenberger]

I'd suggest asking the dealer to take a new set of pads from stock, lay them flat on the table side by side. Expect to see a light-bulb go off above his head when he realizes the inside one is ~1mm thinner than the outside one.

I never fail to be amazed at the bull-fecal-matter dealers and their employees spout in a tone of knowing-all.

[enderw88]

I'd suggest asking the dealer to take a new set of pads from stock, lay them flat on the table side by side. Expect to see a light-bulb go off above his head when he realizes the inside one is ~1mm thinner than the outside one.

Or they will assume the thicker one has to go inboard since that applies "more force"...

[lowflying]

Anyway, I just got back from the dealer. Fitting new rear pads plus an oil and filter change set me back $315(Australian)! The original BMW pads were 144 bucks a pair.

I'm a bit shocked...

[WILDPIG]

LOW FLY-- WELCOME TO THE WORLD OF BMW IN REFERENCE TO OUTRAGEOUS PRICES.. BUT I HAVE GOOD NEWS----- BMW IS A FAIRLY STRAIGHT FORWARD AN EASY TO WORK ON MOTORCYCLE... ALSO THE CLAIM GENERALLY IS-- BMW IS AS RELIABLE AS AN ANVIL-- ALTHOUGH I HEARTILY DISAGREE AS TO THE RELIABILITY YEAR IN AN YEAR OUT FOR BMW...