Boiling brakes?

I was out yesterday for a little run around Cal City. I did a speedy 30 mile race loop and everything was great. I topped off the tank and headed for the hills to do a little rock climbing on my way to Randsburg, this was around 9:30 AM. At the top of the ridge, the brakes were feeling a little soft. On my way down the first serious rock slide, the rear brakes went away COMPLETELY and the front was starting to go. I didn't even think it was that hot out. The brakes cooled over an early lunch in town and seemed to work ok on the way back but I stayed out of the hills and took a speedy route instead.

Now what to do? The bike is a good old fashioned 320 pound 2000 XR650R. It may be my fault.....while the pads and rotors have been changed numerous times, the brake lines and fluid have never been changed. I guess I never thought much about it since it always "works". I have run way harder in more heat than yesterday without fail. The rotors are even Braking waves. The only thing really new is the Braking CM46 pads. I have ridden and raced on them three times with awesome results but I have never been rock climbing with them before yesterday.

I know little about brake fluid. Can 6 year old fluid just "quit working" (yea I know I should have changed it before now)? What about the brake lines? At 6 years old, should I change them too? Unless the CM46 pads created undue heat at the slow speeds in the mountains, I am sort of bewildered. Any recommendations? What kind of fluid are you DEZERT RACERS using? I am likely to use something Pro Honda.

It is possible for the brakes to heat up, along w/ the discs. That can cause the pads to glaze over if you REALLY use them hard. But, generally if the pads get glazed over, then usually you won't have much left of your brakes at all.

As for changing the brake fluid, I don't really think thats nessecary. I have the exact same bike that you do, and while I've done a top-end on it once, I've yet to worry about the brakes anymore than the nessecary brake pad change. I've changed the pads front and rear, and replaced the rear rotor. Haven't had a problem since.

Fluid would be my thought. My background is supersport and its at least a two or three times a season thing on my race bike.

What color is your fluid? It should be clear if it not (say brown) then its time to change. Its easy to do and only costs a few bucks so even if its not the fluid it will only cost you a few bucks and an hour to find out.


Was this a problem before. If it was not an issue before, there might be something making the brakes drag a little. If they don't release when you let off the brake, they will fry. This happened to to one of my friends on his CR500. The return passage in the master cylinder got clogged. The brakes dragged a bit and they got hot. Got so bad he said it was glowing red in the day time!!! We ended up removing the pads so he could get back to the truck.

Test it this way. Try and push the pads apart. If they go easily then this is not the problem. If they don't, take both the caliper and master cylinder apart and clean everything. If they do push in, then this is not the problem. Replace the brake fluid and see if it happens again.

Flush with #4 fluid. Cheap insurance. I'm due also.

Use motul rbf600 dot 4, well worth finding it

Flush with DOT #5 fluid and put an over size rotor on it.

might dot 5 collapse the lines?heard something about silicone base...........doing something to the inner line material

might dot 5 collapse the lines?heard something about silicone base...........doing something to the inner line material

Oh boy.... Any links? Remember, I use only WD-40 on my chain and the cheapest oil in my motor. :excuseme:


Tried down shifting? Or did you already do that?

Flush with DOT #5 fluid and put an over size rotor on it.

DOT 5 is not compatible with the seals used for DOT3 and 4. However, DOT 5.1 should be OK. It should be DOT6 not 5.1, as 5 and 5.1 have nothing to do with each other. DOT 5 is a silicone based material. DOT 5.1 is much more like the glycol based DOT 3 and 4.

DOT 3 is higher boiling than DOT 4 when it's new. However, it picks up water fast. Contaminated DOT 4 is higher boiling than contaminated DOT 3. Normally DOT 4 is the way to go.

very nice pic, looks like a fun place to ride

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