Fried rear brake

[DucNaked]

Okay I'm in Colorado on a road trip, the guys I'm riding with say my brake light keeps coming on.  I stop, nothing seems like it's sticking so I continue on.  Then headed up a mountain pass the bike seems like it's lagging and down on power and I pull over. The rear rotor is cherry red. The heat melted the the plastic on the speedo sensor and the brake line.
Can't bleed the system. Pulled the caliper off and couldn't bleed with a vac pump. Pulled the line off caliper and still couldn't get any fluid to move from the master. Is this "fixable" on the road or is my master and caliper most likely cooked.

[DarkStaR]

If the light was turning on, my guess is that the brake lever/pedal was mis-adjusted, as that's where the switch is.

Considering the trouble shooting results so far, I'd check if the line collapsed internally or test the master without the line.

If all else fails, keep going without the rear brake, and enjoy the rest of your trip

[WTSDS]

+1 on heading home without the rear brake.

Sounds like the rotor may be "toast" too, and better take a look at the wheel bearing as well.

I almost had a similar hassle with my rear brake, a build-up of crud had stopped the caliper piston from retracting and the pads were dragging.

http://www.ducatimonsterforum.org/index.php?topic=46781.msg849359#msg849359

[DucNaked]

I've had the caliper off I haven't completely removed everything. I've been riding the last couple of days without it. I'm enjoying myself, but I'm not 100% without the rear brake.

I haven't made any adjustments to the system in about a year other than bleeding it. If there was air in the line could that somehow apply the brake or could the difference in altitude have some effect on the system?

Is the rotor cooked from getting that hot?

I think tomorrow I can get to some tools so I can dig a little deeper.

[DucNaked]

+1 on heading home without the rear brake.

Sounds like the rotor may be "toast" too, and better take a look at the wheel bearing as well.

I almost had a similar hassle with my rear brake, a build-up of crud had stopped the caliper piston from retracting and the pads were dragging.

http://www.ducatimonsterforum.org/index.php?topic=46781.msg849359#msg849359

Didn't see your post before I posted.

[Speeddog]

Rotor's most likely cooked, I wager it will assume a 'cone' shape when you unbolt it.
Caliper cooked as well.

Master may not be damaged, but something may be wrong with it.
If the brake light was on continuously, then the pedal stuck down, or the piston stuck in the master, or something similar.

[H-2 CHARLIE]

   It was working fine for some time then it went SOUTH ?   Do you ride in bad weather alot ?  I love to wipe my rotors down alot with WINDEX about every other ride or so . I every few mo. use compresed air to blow the crap out of the pistons so they dont stick up .                                                                                                                           Even  a rock getting stuck in there will scar the rotor .

[DucNaked]

   It was working fine for some time then it went SOUTH ?   Do you ride in bad weather alot ?  I love to wipe my rotors down alot with WINDEX about every other ride or so . I every few mo. use compresed air to blow the crap out of the pistons so they dont stick up .                                                                                                                           Even  a rock getting stuck in there will scar the rotor .

Everything was working fine. My problem started about four hours into the ride. Maybe something got in there from the trailer ride from Maine to Colorado.

Rotors don't look scored they just look cooked.

[Slide Panda]

I had a pad hang up due to crud on the retainer pin with results much like yours... but a touch worse. As I didn't know that was happening and applied a bit of rear brake as I was coming to a halt after pulling off. When I did the rear locked boiled the fluid and blew the line from the fitting. Once that happened... bike rolled fine and I got home.

My rotor was white hot - it and of course the pads and line were done. But the caliper and master were fine.

So it could have been something as simple as gunge on your pin... Now, mine come out get hit with a scotch brite and then some metal polish to make sure that NEVER happens again.

[Cloner]

I'll wager that Speeddog is right about the piston being stuck or somehow kept from returning to its rest position.  These master cylinders have a return port that gets blocked if the pedal doesn't travel all the way up (and hence, the piston doesn't travel to its intended rest position within its bore).  I have seen this happen on several Ducatis and a blocked return port was the culprit in every instance.

Dismount the master and check to see that the piston is fully forward in its bore.  If it's not, hydraulic pressure builds in the line and this condition is only exacerbated when things start to heat up.  You should be able to crack the bleeder and relieve the pressure, but if the port is blocked at the master you won't be able to get fluid from the reservoir, even with a vacuum bleeder. 

Usually disassembly and a thorough cleaning of the master cylinder followed by correct adjustment of the pedal throw will fix it.

[bikepilot]

I'd triple-check that the pedal isn't mis-adjusted and that it is returning fully.  Only depressing the pedal will cause the brake light to come on (unless there's an independent fault with the brake light) with the stock setup.  You haven't swapped out the brake light switch with a pressure switch have you? Could be as simple as you getting a bit sloppy or wearing different boots and accidentally resting your foot on the pedal.

good luck and enjoy colorado!

[DucNaked]

Life has had me busy and haven't had time until now to work on my brake problem. I tried to have it covered under warranty, but that didn't happen.   And  honestly I don't trust them anyway.

Took the caliper off and cleaned it up a little. Took my compressor and blew some air through it and the pistons snapped shut with no problem. I am able to push the pistons back with a little effort. Nothing seams to be dragging or hanging up.

Took the master all apart cleaned it and reassembled. Put everything back together and I'm able to get fluid to pass through the entire system.

I found out why my brake light was coming on. The screw that holds the switch to my rizoma rearsets had come loose and was allowing it to rotate and trigger the light.

I think the cause of my problem is a combo of my rizoma rearsets (I had to move the brake line from stock routing) and my new exhaust. With the current routing my brake line is 1 1/2 to 2 inches from the exhaust. Is this close enough to boil the fluid? I'm going to order a longer line on Monday so I can get it back to stock position.

I've got a couple of questions. How do you correctly adjust the piston into the master. Will Motul rbf600  http://www.stoptech.com/Products/brake_fluid.shtml help?
Can i take the caliper apart and lube it with something?

[ducpainter]

You want about a mm of freeplay before the pushrod hits the piston.

Eric uses the 5.1...I'd think a line that moves away from the exhaust would be enough.

Castrol and Brembo both make brake 'greases' for assembly purposes.

[Howie]

Since you are having a problem I would add another half a mm to ducpainter's recommendation.  Do your rearsets have a return spring?