Rear Rotor heating?

[rjdick]

I recently got riding again, after my LT wreck in March, I picked up a sweat 05 RT and I'm lovin it ! The bike had recently gone through it's 6K service when I got it (at 6600mi). I've been on it a week and I noted that the rear brake bias was poor, but initially thought it was just a difference in the LT-vs-RT. However today I noticed that the rear rotor is discolored, looks heated? Has anyone else seen problems with rear brake heating issues ? I don't know the riding style of the previous owner, before you ask, and as for the function, I find the need to overly rotate my toe to get a reasonable "hold" on an inclined stop light.

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[Pickaxe]

I recently got riding again, after my LT wreck in March, I picked up a sweat 05 RT and I'm lovin it ! The bike had recently gone through it's 6K service when I got it (at 6600mi). I've been on it a week and I noted that the rear brake bias was poor, but initially thought it was just a difference in the LT-vs-RT. However today I noticed that the rear rotor is discolored, looks heated? Has anyone else seen problems with rear brake heating issues ? I don't know the riding style of the previous owner, before you ask, and as for the function, I find the need to overly rotate my toe to get a reasonable "hold" on an inclined stop light.

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I've been through all this with my dealer and even they were surprised at the heat generated into the caliper and disc. They first suggested and probably quite rightly so, that it maybe my riding style. I pointed out that I ride motorcycles with high vis decoration for a living, and instruct others to do so and they took the situation more seriously.However, after exhaustive tests and riding other 12RTs,STs etc. I can confirm that "they all do that sir".

I wouldn't worry about it, just use the bike.

[Ken H.]

Well some heating, even a lot of heating is normal. After all, that's what brakes do. Convert motion energy to heat energy through friction.

 

The question of course is how much is too much? If there is no evidence of excessive (remember some is normal) brake drag when the brakes are not applied, I suspect the bike is just fine.

 

At any rate your dealer running a ABS diagnostic routine on the bike will tell you one way or another if there is a issue.

[CTRBLNCD1]

Have your dealer through it on diagnostics and read the time-lapse for braking. Yep, they can pull from the computer on the bike the amount of time ( down to tenths of a second I think ) you've braked, readings for both front brake and rear brake. Also ABS activation time can be read. Do this just to verify that you aren't possibly dragging the rear brake unknowingly while riding. But yes, they do get hot!!!!

[Pickaxe]

Have your dealer through it on diagnostics and read the time-lapse for braking. Yep, they can pull from the computer on the bike the amount of time ( down to tenths of a second I think ) you've braked, readings for both front brake and rear brake. Also ABS activation time can be read. Do this just to verify that you aren't possibly dragging the rear brake unknowingly while riding. But yes, they do get hot!!!!

They did that on my bike, however, what does it prove? I think mine reported 10 hours of rear brake and 2 hours of front brake activation, since the bike was new. If the brakes aren't binding and the rider isn't accidentally applying them whilst riding, its got to be down to design.

The rear caliper on the 12RT gets very hot, even after a short spell of use. Even if you drag the brakes on an ST1300 the rear caliper hardly gets warm at all.

I blame BMWs servo brake system, which I think even BM have decided to move away from in future.

[CTRBLNCD1]

Ummm, sounds like you're favoring the rear brake too much (being very open minded here, not flaming). If you're using 10 hours rear brake, 2 hours front brake, you aren't braking properly. You're not braking properly because of the 8 hours of SOLO rear braking. Why? There's one disc in the back, it's a 10.4 inch disc versus the TWO 12.6 inch discs up front. ALSO, the caliper in the rear is a two piston caliper, while up front you have TWO 4-piston calipers. That little guy in the back has to work VERY hard the 8 hours of braking on its own. That in turn heats up a disc and discolors it, it's not the servo assists fault.

[bakerzdosen]

Ummm, sounds like you're favoring the rear brake too much (being very open minded here, not flaming). If you're using 10 hours rear brake, 2 hours front brake, you aren't braking properly. You're not braking properly because of the 8 hours of SOLO rear braking. Why? There's one disc in the back, it's a 10.4 inch disc versus the TWO 12.6 inch discs up front. ALSO, the caliper in the rear is a two piston caliper, while up front you have TWO 4-piston calipers. That little guy in the back has to work VERY hard the 8 hours of braking on its own. That in turn heats up a disc and discolors it, it's not the servo assists fault.

He's only been on the bike a few miles. I think you meant to say "sounds like the previous owner was favoring the rear brake too much."

[CTRBLNCD1]

He's only been on the bike a few miles. I think you meant to say "sounds like the previous owner was favoring the rear brake too much."

 

 

Right, that's what rjdick said, but pickaxe mentioned the 10 hour front 2 hour rear , and I was under the assumption that he was the only owner since he didn't mention it being bought preowned. I dunno

[Boffin]

He's only been on the bike a few miles. I think you meant to say "sounds like the previous owner was favoring the rear brake too much."

 

 

Right, that's what rjdick said, but pickaxe mentioned the 10 hour front 2 hour rear , and I was under the assumption that he was the only owner since he didn't mention it being bought preowned. I dunno

 

Pickaxe is a UK motorcycle Police Officer and Instructor and has been trained how to ride bikes properly. I would put money on him being able to hustle his R1200RT or his ST1300-P down a road faster and more safely than 95% of other users on this board. He knows how to use the brakes. Period.

 

Andy

[Pickaxe]

Boffin,

Many thanks for your kind comments, although I wasn't trying to promote my riding experience, but just show that I had a resonable amount of knowledge.

I just wanted to explain that the rear caliper and disc unit does get very hot compared with other machines. This may or not, be quite reasonable from a brake design point of view, and is not attributable to the incorrect use of the brakes.

Incidentally, when I deliberately changed my braking distribution, in favour of more front brake, the rear unit still got very warm.

BTW, I am the original and sole rider of the bike, which at the time of the brake stats, had covered approx 6500 miles.

Just for the record, I'm not a big fan of BMWs servo brakes, which, IMHO are over complicated for what they achieve, and lack the feel and control of more conventional systems.

However, they have improved since their introduction on the 1150.