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Discussion Starter · #1 ·
Went for a ride tonight and while I was doing my normal pre-ride check I noticed that the rear brake was no longer working. I know it was worked a few days ago, I use the rear all the time when I ride. The fluid level is good, and I didnt notice any leaks. Tried pumping them a few times and went around the block a few times. They never would work. They seem to be clamping a very little but not enough to even hold the bike still when sitting on it... Any thoughts? --Matt
 

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How far down is the brake lever traveling? It's should be rock solid. If not, you either need to change the pads or more likely, you have an air bubble in your brake fluid line. Maybe you should bleed them.

-J
 

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Discussion Starter · #4 ·
The bike only has 1200 miles on it, I cant imagine its the pads. The lever moves through its full range of travel very easily. there is little resistance, and it is not progressive... IE it does not become more firm as you apply pressure to the lever. Im guessing it's air in the lines, just seems strange as there was no period of degraded performance. It just stopped working all at once. --Matt
 

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Check the linkage, pads, fluid color, rotor color - you could be a "brake dragger" and not know it, pretty common trait in off-road riding. This habit will use up pads, rotor, and fluid pretty quick.

If there is basically no fluid resistance in the lever, you could have a bad (defective) seal in the rear master cylinder, KTM had this problem in '06 off-road bikes, you could plan on the defective seal failing within 20-22 hours of usage.

If the pads and rotor are ok, my guess is a bad seal. I would back bleed new fluid into the system with a vacuum bleeder, if you have no brake then it's most likely a cylinder issue.
 

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The pads are the only part that would not cause the problem. Seig brought up a good point. Some bikes came out of the factory with a brake drag problem. I know of a couple where the rear brake actually went up in flames. Yours may have overheated just enough to destroy the seal.
 

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Sieg and Howie are right...but Sieg brought up the best and 1st place to check and that is the linkage from the arm to the cylinder...if the clip is missing...that could be the route to go to solve your problem!
 

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From personal experience, it's really hard to kill that rear brake master. I hang up on my rear caliper. The result was that the whole rear rotor and caliper go so hot that the brake line blew loose from it's end fitting, due to a brute bit of thermal exchange that *really* boiled the brake fluid. But, even after that moment of torture - the rear master function just as it had before, one a new line, caliper, pads and rotor were in place... yeah.
 

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Discussion Starter · #9 ·
Did the bleed this evening, and after much bleeding and lots of pumping on the damn lever I once again have some clamping force.. How much remains to be seen. I cant move the bike when sitting on it but I have to get out and ride it. I may ride the rear brake a little, I notice that my toe is on the lever a lot... too many years riding dirk bikes I guess. At least Im not afraid to use the rear which many of my street riding buddies are.

We will see, the bike under warranty but Jacksonville is over 100 miles from Savannah and I hate not bieng able to fix it myself, I need to go out and buy a vacume bleeder... --Matt
 

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Any update Mats2r? Mine just did it too- at 1500 miles(almost 1 y.o.). Can put the pedal down to hit the cat. w/ very little clamping force. Don't think there's enough adjustment in the linkage to cover it, that and I stripped the hell out of the heel guard screws trying to get at it(what - they weld them on or somthing?).
Newbe question- is it common for them to need bleeding annually?
Thanks folks!
 

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Master cylinder? I'd go back to the dealer.
 

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Thanks for the replies. Too nice to leave it w/ the dealer for a month just to have him bleed it and return w/ the same problem- there's no visible problem/leaks. Bleeded (?) it yesterday, but left it in place(upside down) might have seen some bubbles, but I read you gotta flip it to do it right :-X. will try again.
I guess the question is- how much can we expect out of it. Is it supposed to do this?
 

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I have had this happen several times on my S2R 1000.. One time during a ride.. bleeding is tough to do if you remove the back tire take off the brake place it on top of router and then bleed with a vacuum pump. look at the cush drive when u get the tire off (had that come apart during a mountain ride).. good luck [thumbsup]
 

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howie said:
Try bleeding first. If that doesn't help I would expect a bad master. The bleeder screw must be on top to bleed successfully. SR2? Is the bike still under warranty?
+1. Had to bleed the brakes on my 2007 S4R at about 600 miles. Same thing. Should be good for a while. My old 996 needed a bleeding every year. Something about the upside down caliper. My friends 748 the same thing.

If you do a conventional bleed, you have to dismount the caliper to get the bleeder at the top. With a mity vac (vacuum pupmp) you may be able to get away without taking it off. Or take it to the dealer.

That is 99.9% likely the problem.
 

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Same problem. Just dropped the bike off at the dealership yesterday. I have an s2r 800 with 5k miles (1yr old). Plenty of fluid, but not an ounce of brake. The service guys should be contacting me today or tomorrow. Considering what time it is, probably tomorrow. I'll keep you posted on the results.
 
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