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Discussion Starter #1
Anybody helps me please!

My rear brake works like charm when the bike just starts. After 30mn city ride with the slightly use of rear brake and it starts to loss pressure little by little until there is no pressure!

I put DOT 4 and bleed the brake. I come across somewhere they mentioned about the problem and was advised to keep oil at the minimum level in the reservoir, still no help!!!

Appreciate all of your ideas and will try.
 

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Probably has moisture in it.

Flush it really well and put in fresh fluid from an unopened container.
 

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Try the reverse brake bleed, sounds like air is lingering in there somewhere...
(That you can also do for the clutch by the way)

 
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Why are you using the rear brake so much that you miss it?

I get it, something is wrong, you want it fixed, but honestly, I don't think I'd ever even notice my back brake not working....
 

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I find it really annoying when I hear people "why do you use the rear brake" or "You dont need to use the rear brake"

Coming out of corners; dab it.. keeps your front end down.

Breaking through a steep corner in street riding.

Tap it a bit to shave off speed

Emergency breaking/steering bike while breaking.
 

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Since you just serviced you brakes I think there is still air in the lines. It is really hard to get it out on the rear caliper because of the location of the bleeder port being located on the bottom. I had to remove the caliper to position the bleed port on top and then bled it so the air bubbles can escape. I was using a vacuum bleeder so it was pretty easy.

Hope this helps.
 

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Discussion Starter #10
@LaDrucati @vfrman that's such fantastic points you made and thank for understanding my situation.

I find it really annoying when I hear people "why do you use the rear brake" or "You dont need to use the rear brake"

Coming out of corners; dab it.. keeps your front end down.

Breaking through a steep corner in street riding.

Tap it a bit to shave off speed

Emergency breaking/steering bike while breaking.
 

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Discussion Starter #11
Appreciate all of the useful info!

@jwm2k3 checked the pads and it's ok. Going to give a try as @Mtech suggestion, a vacuum bleeder. Sounds like the air trap somewhere.

Will keep you posted
 

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Discussion Starter #13
Appreciate your suggestion! It's a great help to me... I'm organizing a weekend ride on the twisty road up the mountain this coming Saturday so need to get checked and fixed before that...:)

Mityvac is your friend...
 

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I also have a mityvac....

Best thing to do is remove rear wheel, unbolt caliper and turn it upside down while using the mityvac...

Good luck.
 

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This may help...


As jwm2k3 says, it is a hell of alot easier with the rear wheel removed, however it still can be accomplished with the wheel on.

I usually change the clutch and brake fluid at the same time and flush each reservior 3 times to try and use all the DOT 4 up. No point in hanging on to what's left in the opened bottle of fluid.

I was a bit sceptical about pumping all the old fluid out and then wiping the reservior clean with a paper towel, however I was surprised at the amount of gunk in the reservior-especially the clutch.
 

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Discussion Starter #16 (Edited)
SOLVED!!! I WAS WRONG. ITS NOT I requested my local dealer to use vacuum fluid bleeder... but it couldn't suck air & fluid out and seems like a blockage somewhere... Together we ruled it out, disassemble, cleaned it and put new fluid Motul DOT4 and concluded that it done and working...

I took a 1 meter ride and felt no pressure at all... I went straight home and did my flush in a hope to build more pressure, no use! I suspected there was still air trapped somewhere or brake cable issue...

Came back to the shop next morning, reflush a fluid, no luck... all frustrated for a moment!!!

Then jwm2k3 comes to my mind (thanks you lots) unbolt caliper and turn it upside down... It works like charm... Pressure built up quicker and city ride no issue... Took 400miles ride, no issue... :-D

This is such a wonderful experience to me and the shop mechanics since ducatis are rare in my country.... Thank you all!! Have a good riding day...
 

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Insure the reservoir vent hole is not plugged, else as the system expands and cools it liable to pull air in around the master piston rod. I struggled with this on my track bike having to constantly bleed it between sessions, cleared the vent and the problem went away.
 

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Discussion Starter #18
"reservoir vent hold is not plugged" interesting

"reservoir vent hold is not plugged" interesting but could you share with me just a picture so I have better idea what you are referring to?

Insure the reservoir vent hole is not plugged, else as the system expands and cools it liable to pull air in around the master piston rod. I struggled with this on my track bike having to constantly bleed it between sessions, cleared the vent and the problem went away.
 

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It could be moisture but it could also be a bad seal in the valve. The rubber used in many of these bikes is not very good and breaks down easily.
Another issue could be heat. Mine lost braking power when the fluid boiled over time with it located so close to the exhaust.
Either way bleed out all the old fluid and if that doesn't work then it's probably the part in the photo ImageUploadedByDucati.org Forum1408143697.019992.jpg
 
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