Join Date: Jul 2009
Location: West Chester, OH, USA
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.
drdave39-2010 Multistrada 1200S Touring: Lowered, heavier springs, Ohlins SCU, Tuneboy-ed, 43 tooth rear, M50 Monoblocks. 2018 KTM 690 Duke- my mini-Multi!