A new theory of that crappy rear brake... - Ducati.ms - The Ultimate Ducati Forum
 
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Old May 2nd, 2018, 5:35 pm Thread Starter
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A new theory of that crappy rear brake...

first apologies for no pictures, we were tearing in and not stopping to snap. And a shout-out to the guys at the Powersports Store, Cincinnati's newest independent shop.

After major service on my 2010S, no rear brake at all- pedal bottomed with zero pad movement. I have been following the recent brake threads, as mine sucked before the service anyway. I have gone to the larger master cylinder with no change. We added the bleed fitting at the ABS, and then did a vacuum bleed from the new fitting. Holy crap! TONS of air, discolored fluid (even though the system had just been flushed) and even some particulate stuff! So- problem solved?- Nope, not so fast- brake lever still bottoms and no brake. WTF? Take it home, do the weight on the lever overnight, then crack the new ABS bleed valve in the morning- got a tiny bit of air. And still no brake! Took it back to the shop, and we are looking at it. I'm pumping the lever, and the mechanic says- "Wait a minute- look at the rear reservoir!" Every time I pump the brake lever, the fluid rises a bit- like AIR is coming in. Rear master is sucking air on every stroke.

So I look at it closely- and EUREEKA! It comes to me- the master is less than "TWO INCHES FROM THE CAT"!!! Seal are being exposed to 500 plus degrees! Of course seals will go bad due to the heat, and quickly start to leak. Then, as air gets into the system, it accumulates at the top of the ABS unit!

I wonder if the Cat was an "add-on" to the original design due to changes in Euro emissions? With the idea in mind, I stopped at the local KTM dealer on the way home and looked at several of their bikes- they all have large cats, and the masters for both clutch and brake are at least 8 inches away from them!

So- we are going to either rebuild or replace the rear master, and wrap it in some exhaust insulation to help cut the heat. The repeat the top bleed, and monitor. And gripe to Ducati, of course...

I will take some pics to illustrate what I found and also of the insulation install.

Dave

drdave39-2010 Multistrada 1200S Touring: Lowered, heavier springs, Ohlins SCU, Tuneboy-ed, 43 tooth rear, M50 Monoblocks. 2018 KTM 690 Duke- my mini-Multi!
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Old May 2nd, 2018, 5:38 pm
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Have you watched this? Goes along with what you are saying.


I just flushed my brakes. Rear is not bad... I am still going to add the bleeder at the ABS module, though. Don’t want to have to take my rear caliper off and unbolt the lines again to get it above the module.




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Last edited by Chuckracer; May 2nd, 2018 at 6:12 pm.
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Old May 2nd, 2018, 6:08 pm
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ones without cats still do it. non abs ones don't.

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Old May 2nd, 2018, 9:15 pm
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I was going to raise my brake pedal a bit as it feels a bit low to me. It does work maybe a bit spongy . So looked and realized it’s not adjustable (what crap). Pressed it and noticed what looked like a pulse of dirty fluid pushing into the reservoir and back into the tube when released. The reservoir looks to be half dirty and half clean, with the dirty at the bottom. Pumped several time and never noticed a change in level of the reservoir.

The bike has 14000 miles and had 9000 when I purchased it a year and a half ago.

Of the 4 bikes I looked at and road only one had the brake that would go full stroke with no break action, all others worked.


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Last edited by Chuckracer; May 2nd, 2018 at 9:26 pm.
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Old May 3rd, 2018, 7:15 am
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My rear brake is fine w/ full Termi/cat delete. '13 master + bleeder @ rear abs circuit and routine yearly flush/bleed, which I do regardless.

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Old May 3rd, 2018, 7:29 am
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Mine is a 2014 stock with cat. Has 10k+ Front brake has been bled once. Never bled the rear. Rear still working. I bought the heat guard thing that guy was making when I got the bike. Never even installed that. Scared to touch it. Shouldn’t have even typed it.
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Old May 3rd, 2018, 9:18 am
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Quote:
Originally Posted by Wolverine1 View Post
My rear brake is fine w/ full Termi/cat delete. '13 master + bleeder @ rear abs circuit and routine yearly flush/bleed, which I do regardless.


I just got my 2012 five weeks ago. It came with a full Termi that the PO had installed on day one. Rear brake felt ok-ish when I bought the bike, but I also had nothing to compare it to. Well, Multis anyway.

Brakes had never been bled and it was at 19.5K. Vacuum pump bled it myself, raising the caliper above the ABS module. Seems a little better now, but pretty similar.

I donít feel like I could lock up the rear, but I am also wearing size 13 wide Sidi boots and can only get half my boot on the pedal. Might try turning off ABS completely and see if I can lock it up. That would be a good test.


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Old May 3rd, 2018, 9:18 am
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Quote:
Originally Posted by shorton View Post
Mine is a 2014 stock with cat. Has 10k+ Front brake has been bled once. Never bled the rear. Rear still working. I bought the heat guard thing that guy was making when I got the bike. Never even installed that. Scared to touch it. Shouldnít have even typed it.


You made me LOL for reals. Thanks for the laugh.


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Old May 3rd, 2018, 9:39 am
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FWIW YMMV....... I installed the rear bleeder and did the caliper high bleed. Got out lots of air. Can lock the rear now with abs off. Running valvoline fluid from flaps. This is a 13 mts st.
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Old May 3rd, 2018, 10:53 am
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Multistrada 15 DVT. no cat, full termi. After I bled the system from the abs after installing the full termi, I have had no issues with my rear brake. Works well.
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