I’m having problems bleeding the Brembo clutch master cylinder on my 2012 Multistrada. I have passed through about 125ml of fresh fluid and am still seeing air bubbles in the bleed pipe. More worryingly is the occasional cloud of something grey that looks like a drop of Robinson’s cordial dissolving in a jug of water. Flushed with the success of my first rear brake caliper rebuild, I have bravely or recklessly decided to strip the m/c down and fit a new seal and piston kit. Is there anything I need to be aware of or is there a little wrinkle learnt from experience that makes the whole job simple ? Thank you in advance. Andy
Andy, Have you already got the seal kit? I couldn’t get one for my Panigale, they wanted to sell me the whole lever assembly for £240 quid or something! I finally found some KTM Brembo spares that were identical, have a look at my post, no 57 in this https://www.ducatiforum.co.uk/threads/alternatives-to-the-genuine-ducati-parts.594/page-3 might help with a few things, mine had to be bled in two positions, at the slave cylinder and the master cylinder. Good luck!
If the cloudy fluid is grey metallic you may have a slave cylinder/push rod issue, it looks like grey metallic pearlescent fluid when the clutch push rod is spinning the piston in the slave Poucher, the Ducati clutch master cylinder kit may not have been easily available in 2018 but it certainly was in spring 2019 when I had issues with my 999 clutch. Shame they don't do one for the front brake!
The fluid at the slave end is crystal clear and none of the, let’s call it contamination, was evident in the initial bleed. The contamination is only evident from bleeding at the m/c nipple. With the difficulty in bleeding air, the two symptoms are consistent with the seals failing. As I can’t get the seal kit until Monday, I’m going to see if the m/c loses pressure under constant lever pressure provided by an elastic band which is, I understand, how the workshop confirm a seal and piston change in the brake m/c is working. Sounds old school but if it works, who am I to question. Andy
Good call ..... ordering Brembo overhaul kits via KTM spares has saved me stacks . If KTM can do it , why can't Ducati .... for the exact same brakes ??
But only if you then bleed the fluid fully to remove the resulting dissolved air. This lever tying trick is only a temporary fix as it simply forces air in the system to go into solution within the brake fluid.
Andy, when the slave went on my 999 due to a spinning clutch push rod the aluminium particle contamination from the slave came out when bleeding the master as blooms of grey pearlescent fluid into the reservoir. It was evident at the slave too but the entire system got contaminated by the metal particles, I think the low density of the alloy particles means they effectively floated to the top of the system which seemed counterintuitive but that is what must have occurred. I ended up with a new master piston and seals due to the piston seal getting damaged at the system inlet, a new slave and a new push rod with a locking ring. Have to say the system now works a treat and bleeds perfectly.
I will check the slave but it is an Oberon and if I recall, it has that eminently losable pin to stop the rod from rotating. Andy
@Denzil the Ducati, no sign of the clutch rod rotating, the anti rotation pin was in place. However, something is clearly not right. Without having broken any joints, I re-fitted the slave and had no resistance at the lever, none. Bled the system through and there was a huge amount of air coming out of the m/c bleed nipple and I mean huge, very little of which found its way to the slave. No idea where that came from. I have good pressure now but as I’m off to the Welsh side of Hey-on-Wye for a few days touring next week, I think I might just throw money at it and fit a new slave as well as fitting a new piston and seal kit. Andy
No experience with master cylinder, b up the slave on my M1200 is leaking 3600 miles on the clock. I am having it changed under warranty, but seriously looking at an Oberon slave. They look to be more reliable and the reduced pressure required to operate the clutch should help extend the life of the master cylinder seals.
Spent the day with Carole sharing a few beers and watching the MotoGP when I had a brainwave. Looked on the Oberon web site and the clutch slave cylinder for my Multistrada is the same model as my 748R so when I got home I robbed the 748R slave cylinder and swapped over the potentially suspect Multistrada slave cylinder. The system is bled and the pressure feels good and possibly a little bit better than before (or that might be wishful beer thinking). Will bleed the system again in the morning and then head out to see if the change has made a difference. On the off chance, does anyone know if Oberon offer a refurbishment service or a seal and piston kit ? Their web site was not that informative. Andy
I think you will find that Oberon cylinders have a lifetime warranty, but you have to register a return before sending off for repair/ replacement. If you check out the website and look up ducati clutch slave cylinder the terms of the warranty are explained. Hope this helps, good luck!
I seem to remember there was a legal case brought by an individual against Brembo, after the brakes on the bike failed on a rebuilt M/C using one of their kits, which resulted in a nasty accident some years ago, hence why most dealers will not carry seals/internal parts etc. to avoid any liability, so quite why KTM still do is a mystery, unless there is a disclaimer on the packaging.
Well, bugger, I’m still getting small air bubbles in the bleed tube at the m/c so it isn’t the clutch slave cylinder, unless the one off my 748R has failed in exactly the same manner, which I doubt. Spoke to Oberon his morning and yes, @hypermotbloke, you are correct , their slave cylinders have a life time, return to factory, warranty. Unfortunately they do not offer a service kit or a return to factory service but the lady I spoke to has said that if I return the unit for a pressure test under the warranty, they will let me know how much new seals will cost if it passes (which I think it will). Off to MR now to pick up the clutch m/c piston and seal kit although I’m now in two minds about doing the job before our trip to Wales later his week, the MR workshop is way too busy if I make a mistake Andy
Just a thought is there an air tight seal on the supply hose between reservoir and master cyl hoses have been known to draw air but not show signs of fluid leakage, just saying.
Just back from MR’s with a m/c piston and seal replacement kit. I think a bite to eat first then out into the garage and get busy fitting it. Bike rode a lot better having bled the system so fingers crossed, this will be it. Andy
Time to close out the thread. Clutch master cylinder has been disassembled, having only removed the hand guard and lever. I left the mirror in place and I let the clutch fluid reservoir dangle on the pipe as it self supported. Once you have removed the internal circlip, the piston and seal assembly pops part way out under pressure from an internal spring. Note : there is a shaped pin that sits in the spring and locates in a recess in the m/c. Mine didn’t come out with the spring and I only found it when I started to clean the inside of the m/c. The OE piston and seal assembly was clogged with what looked like blobs of black graphite grease, the seal nearest the lever plunger was rigid like a piece of plastic whilst the other seal in the body of the m/c was so flimsy, you could turn it inside out too easily. The inside surface of the body of the m/c was also coated with the same black graphite like grease. After cleaning with a rag wetted with Dot 4, assembly of the new piston and seal assembly with the spring and pin, was far easier than I anticipated, literally just a (gentle) push fit. A trick I was told was to bleed the m/c before re-assembling the lever, just by pushing the piston. You get a longer throw so it only took 3 pumps to get fluid through. Remember to fit the external rubber seal to the lever plunger BEFORE you re-fit the lever. Final stage was to part compress the lever using a rubber band and leave for 10 minutes to check for pressure loss by measuring if the lever gets nearer the handlebar. I’m going to leave it for a few hours and do one last bleed before packing my tools away and riding he bike. Andy
