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Mushy clutch & Fr. Brake

1341 Views 9 Replies 6 Participants Last post by  macraige
After riding in the mountains of CO, UT, NV and WY for several days, both the clutch and the front brake have gotten "mushy" and required a bleeding of the master cylinders to remedy. This has happened to me the last three times I rode my '12 MTS 1200S at altitude for several days. I live in Tulsa, OK which is about 700' msl. My wife rides an ST3s and has never had this problem nor did my previous ST4s.

I added speed bleeders to make it easy to bleed so this is manageable issue. Is this something others have experienced? Any ideas for a remedy or is this just another Ducati eccentricity?
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Happened to my rear brake when I moved from sea level to 9000'. Brake had already been mushy but would go down and hit the exhaust without operating brake after move. I think air in system expanded with the drop in air pressure. Was fine after bleeding. How long since you bled them prior to your move?
I've added speed bleeders to both clutch and Fr. Brake MC so that I can bleed them on the road. Always carry a plastic tube to keep the fluid off the bike parts and a small bottle of DOT 4 to replenish the MC. Not too hard to manage, but would like to make it stop, if possible.
I've added speed bleeders to both clutch and Fr. Brake MC so that I can bleed them on the road. Always carry a plastic tube to keep the fluid off the bike parts and a small bottle of DOT 4 to replenish the MC. Not too hard to manage, but would like to make it stop, if possible.
Hmmm..if its continuing to happen, air must be getting in somewhere during operation. Or bleeding it is not getting rid of the air that's trapped.
don't shake up the brake fluid bottle.

You would be amazed at how much air can be in suspesnion within the brake fluid.
After a lot of research, I have concluded that there is no real fix for this issue. I added speed bleeders and carry a small hose, some extra DOT 4 and the correct size wrench to bleed the MC. The speed bleeders make it pretty easy to do on the road. Given how much I otherwise enjoy riding this bike, it is not a deal breaker.
Yeah, if you have even tiny bubbles at lower elevations, they become big bubbles when you climb elevations due to the lower atmospheric pressure. Maybe bleed it real good before you go to higher elevations? Don't think you can get the brake system 100% sealed off from air. There will likely be some degree of air in it and the problem will exacerbate at higher elevations.
I rode over Trailridge last weekend and must have been luck as the clutch and brakes still work just fine. :D

I have heard of incidents where this happens and they need to be bled so will be awaiting that issue in the future. :ahhh:

Marc
A trick I've used when parking bikes over night is zip tie the lever back to the bar in the compressed position. The air rises and escapes, gives little bubbles a chance to work their way up. I use this a final step in the bleeding process, always come out to a nice firm lever.
fastrob691: Interesting idea. I'll give it a try next time. Thanks.
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